System and method for control scheduling

[background] 1. Field of invention The present invention relates to the field of control scheduling, especially the field of making smooth changes between different control modes.

2. Explanation of related technology Human transport devices serve to move people on the surface and can take many different forms. For example, the person transport device used herein can include, but is not limited to, wheelchairs, powered carts, bicycles, motorcycles, automobiles, hovercraft, and the like. Some types of human transport devices may include a stabilizing mechanism to prevent the device from tipping over and injuring the user of the transport device.

A typical four-wheel wheelchair makes contact with the ground on all four wheels. If the center of gravity of the wheelchair and the user combined is above the area between the wheels, the wheelchair should not tip over. If the center of gravity is located above the outside of the grounding member of the transport device, the transport device will become unstable and tip over.

With reference to FIG. 1A, a typical wheelchair 100 is shown. Wheelchair 100 and user 102 define the frame. The frame has a center of gravity 104 located vertically above the surface 106. As used herein, the term "surface" shall refer to any surface on which a human transport device can rest. Examples of surfaces include flat ground, sloping surfaces such as slopes, gravel roads, and may also include curbs (such as road curbs) that vertically connect two nearly parallel surfaces that are vertically displaced from each other. ..

The surface 106 may be inclined with respect to the horizontal axis 108. The angle at which the surface 106 deviates from the horizontal axis 108 is called the surface pitch here, and is expressed by the angle of θs. The front wheels 112 and the rear wheels 110 of wheelchair 100 are separated by a distance d. The distance d between two wheels can be measured as a line (eg, straight) distance. If the center of gravity 104 of the system is in the upper position between the two wheels 110 and 112, the wheelchair 100 should be upright and relatively stable. Wheels 110 and 112 generally have opposite wheels (opposing couner parts) (not shown) on the other side of the wheelchair. Each of the opposite wheels will share an axis with wheels 110 and 112, respectively. A polygon connecting the points where these four wheels come into contact with the ground (when the ground contact area covers more than the points, the outer part of the ground contact area). The range enclosed by is the range in which the center of gravity 104 can be located when the wheelchair is stable. In various places in the discussion below, this range will be referred to as the footprint of the device. The term "device footprint" used here is defined by a projection drawing of the range (area) between wheels projected onto a horizontal plane. If the center of gravity is above this location, the transport device should be stable.

If the center of gravity 104 is displaced vertically above the surface 106 and outside the footprint (ie, the projection of the area between the wheels 110 and 112 on a horizontal plane), the stability of the wheelchair 100 is reduced and the wheelchair 100 will fall. This will occur, for example, when the wheelchair is on a steep surface. When on a steep slope, the center of gravity 104 will move backwards and the wheelchair 100 will turn backwards. This is shown in FIG. 1B, where the center of gravity 104 is located outside the footprint of wheelchair 100. The center of gravity 104 is shown including a gravitational acceleration vector (g) that linearly moves the center of gravity 104 downward. Wheelchair 100 will rotate about the axis of the rear wheel 110 until it comes into contact with a passing surface.

The user 102 can help return the center of gravity 104 to an upper position in the range between the wheels 110 and 112 by leaning forward in the wheelchair 100. Even if the position of the center of gravity 104 can be controlled in such a limited manner, it is clear that a human transport device such as a wheelchair faces great difficulty when passing through an uneven surface such as a curb or a step.

Another form of human transport would include a control mechanism that would allow the transport to be balanced on two wheels. The two wheels can be connected to a single axis that passes through the center of the wheel. The shaft connects the wheels so that the back-and-forth movement of the device is orthogonal to the shaft. The control mechanism can hold the device and the user in a stable upright position by driving the wheels in the anteroposterior direction so that the center of gravity can be held above the wheel axle. Such a device can further move by allowing the center of gravity to be displaced from the wheel axis in the anteroposterior direction by a certain distance and rotating the wheel to hold the center of gravity in that position. Examples of such devices are disclosed in US Pat. Nos. 5,701,965 and 5,719,425, which are incorporated herein by reference.

<p num="0009"> According to an embodiment of the present invention, there is disclosed a system that performs conversion between a first operating mode and a second operating mode of an apparatus. In this embodiment, the system uses the gain coefficient associated with the first operating mode to control the system in the first operating mode and the gain coefficient associated with the second operating mode when operating in the second operating mode. Includes control loop. In this embodiment, the system also includes a gain selector that activates the control loop using the coefficients associated with the second actuation mode approximately as soon as the device transitions from the first actuation mode to the second actuation mode.</p><p num="0010"> According to another embodiment of the present invention, there is disclosed a method of smoothly operating a device that responds to a control signal. In this embodiment, the method includes a step of determining a value for a control signal, a step of processing the control signal to generate a modified control signal, and a step of applying the modified control signal to the device. ..</p><p num="0011"> Another embodiment of the present invention discloses a method of smoothly switching between modes in a multi-modular apparatus. The method of this embodiment includes a step of determining whether a mode change has been made and a step of determining an offset value if the mode has been changed. The method of this embodiment also has an offset value attenuated version of the control signal prior to applying the control signal to the device in order to generate a smoothed control signal. Includes a step of adding and a step of applying a smoothed control signal to the device.</p>

<figref num="1">Figures 1A and 1B show examples of conventional wheelchairs.</figref><figref num="2A">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="2B">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="2C">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="2D">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="2E">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="2F">FIGS. 2A-2F show various embodiments of the human transport device.</figref><figref num="3">FIG. 3 shows another embodiment of the human transport device.</figref><figref num="4">FIG. 4 shows a simplified form of the transport device shown in FIG. 2A.</figref><figref num="5">Figures 5A and 5B show the relative orientation of clusters of human transport devices operating in staircase mode.</figref><figref num="6">FIG. 6 shows a block diagram of possible operating modes of the human transport device.</figref><figref num="7">7A to 7B are simplified side views of the transport device.</figref><figref num="8">FIG. 8 shows an example of a control loop that can be executed according to aspects of the present invention.</figref><figref num="9">FIG. 9 graphically shows an example of values that can be used in the switching mode according to the embodiment of the present invention.</figref><figref num="10">FIG. 10 is a data flow diagram of one embodiment that determines the control switching value.</figref><figref num="11">FIG. 11 is a flowchart showing how to determine the transition time between various submodes of the transport device.</figref><figref num="12A">FIG. 12A shows an example of a control unit that can be used in combination with the present invention.</figref><figref num="12B">FIG. 12B shows a functional block diagram of one embodiment of the control unit of FIG. 12A.</figref><figref num="13">FIG. 13 shows a control loop that can be executed according to the present invention.</figref><figref num="14">FIG. 14 is a diagram showing an example of a gain table that can be used according to the embodiment of the present invention.</figref><figref num="15">FIG. 15 shows an example of a system executed to smooth a control signal before it is applied to the controller.</figref><figref num="16">FIG. 16 shows a block diagram of a method of smoothing a control signal.</figref><figref num="17">FIG. 17A shows a block diagram of a control loop configured to perform a gain scheduling operation according to aspects of the present invention. FIG. 17B shows an embodiment of a control system capable of smoothly transitioning between modes.</figref><figref num="18">FIG. 18 shows a flow chart of a control scheduling process performed in a feedback control system according to aspects of the invention.</figref><figref num="19">FIG. 19 graphically illustrates the various signals present in FIGS. 17A and 17B.</figref><figref num="20">FIG. 20 shows an example of a control loop that controls the position of the wheels of the transport device.</figref><figref num="21">FIG. 21 shows an example of a control loop that controls the position of a cluster of transport devices.</figref><figref num="22">FIG. 22A shows an example of a control loop in which a centroid estimate can be used. FIG. 22B shows a block diagram of a system that produces the desired orientation based on an estimate of the position of the center of gravity.</figref><figref num="23">FIG. 23 shows an example of a free body diagram of a transport device.</figref><figref num="24">FIG. 24 shows an example of how to generate a data set for estimating the position of the center of gravity of the device.</figref><figref num="25A">25A to 25C graphically show each part of the method of FIG. 24.</figref><figref num="25B">25A to 25C graphically show each part of the method of FIG. 24.</figref><figref num="25C">25A to 25C graphically show each part of the method of FIG. 24.</figref><figref num="26">FIG. 26 shows a graph of a data set that can be used to estimate the position of the center of gravity of a transport device.</figref>

[Detailed description] Aspects of the present invention relate to various control modes for the operation of a human transport device. Different forms of control are possible for each of the various modes. In some embodiments, some modes are very responsive to the user's input commands, while in another mode, the user's input commands are attempted to hold the transport device, and thus the user, in an upright and stable position. Will be completely ignored.

FIG. 2A shows an example of a transport device 200 capable of carrying out aspects of the present invention. It should be noted that although the various contents of the present invention have been described in the context of various transport devices, the teaching of the description is not limited to implementation in human transport devices. For example, various control modes are applicable to transport devices that are not similar to transport device 200 shown in FIG. 2A. Systems and methods that allow smooth transitions between different modes are also applicable to other devices.

The transport device 200 can include a platform 202 suitable for supporting a user person (not shown). Platform 202 can be a chair-shaped platform on which the user sits, similar to that shown in FIG. 2A. However, as will be described later, the platform 202 does not have to be a chair-shaped platform, and may be any form of platform that can support the user. For example, the platform can be a platform on which the user stands.

The transport device 200 also includes an arm 204 that resembles a chair arm. The arm can provide a place for the user to lean on or otherwise support the user. The arm 204 can include a user interface 206, such as a joystick, that can receive directional command input from the user. Other forms of the user interface include roller balls, touchpads, breath sensitive inputs, location sensors attached to the user or clothing worn by the user, voice recognition systems, etc. It can include, but is not limited to, pushbutton controls and the like. By relaying these input commands to the control unit 240 of the transport device 200, the user interface 206 can carry out the movement of the transport device 200 in the desired direction. The user interface 206 can also have an effect on the speed of movement.

The transport device 200 can also include grounding members 208 and 210. As shown in FIG. 2A, the ground members 208 and 210 are wheels. However, it should be noted that the ground members 208 and 210 are not limited to wheels. For example, the grounding member can be a caster, a rigid member (eg, a bowed member shown in FIGS. 22-24 of US Pat. No. 5,791,425), treads, or other moving mechanism. The human transport device having the above and other grounding members is described below.

In embodiments that include wheels 208 and 210, the wheels are in contact with the surface to allow it to move on the surface. Wheels 208 and 210 can be driven by a motor (not shown). Further, by arranging the wheels 208 and 210 in the opposite direction to the coaxial wheels (not shown) on the other side of the transport device, four wheels that come into contact with the surface in transit can be provided.

Wheels 208 and 210 can be attached to the movable arm 212 (or cluster). As used herein, the terms "movable arm" and "cluster" shall refer to an assembly to which a grounding member can be attached. Also, the cluster is a grounding part depending on the context. Sometimes it will refer to the entire assembly that includes the materials and connects them to each other. The cluster 212 may be a rigid member, but may also be a member that can be folded around various axes. For example, referring to FIG. 2B, where cluster 214 is shown to have first part 216 and second part 218, the first part 216 and second part 218 rotate with each other at pivot point 220. Will be attached to. Cluster 214 will include two wheels 222 and 224. The two wheels 222 and 224 can contact the surface at contact points 226 and 228, respectively. Since the clusters are on a horizontal plane, in this embodiment the distance between the contact points 226 and the contact points 228 determines the length (l) of the footprint of the transport device. (Of course, if the cluster is on an incline, the length of the footprint will be equal to the length of the projection of L on the horizontal plane. In this embodiment, the first part 216 and the second part 218 of the cluster 214 Due to the pivot point 220 between, the length (l) of the footprint is variable. When the angle θc between the first part 216 of cluster 214 and the second part 218 of cluster 214 is about 180 °, the foot The print length (l) is maximum.

In one embodiment, the length of the cluster footprint can be shortened so that the angle θc between the first portion 216 and the second portion 218 of the cluster 214 is extremely small. An example of such an embodiment is shown in FIG. 2C. In this embodiment, the outer circumferences of wheels 222 and 224 will overlap. Of course, in this embodiment, the wheels 222 and 224 can be displaced from each other along the Z axis so that the wheels 222 and 224 do not come into contact with each other and interfere with the rotation of the wheels.

Returning to FIG. 2A again, the cluster 212 can be attached to platform 202 by platform support 230. The platform support 230 may include an upper portion 232 and a lower portion 234. (The platform support 230 can also be an integral member.)

In one embodiment, the lower portion 234 of the platform support 230 can be rotatably attached to the cluster 212. To adjust the height H between the cluster 214 and the bottom of the platform 202, the lower portion 234 of the platform support 230 can be rotated around the cluster junction pivot point 236 for a more vertical orientation. .. Also, when the lower portion 234 is rotated vertically, the upper portion 232 can also be rotated around the support pivot point 238 to further raise the platform.

When attempting to lower platform 202, move the lower portion 234 closer to cluster 212. The upper portion 232 can also be moved closer to both the lower portion 234 and the cluster 212.

The transport device 200 can also include a control unit 240 (or electronics box). Generally, the control unit 240 sends commands to various motors that can be included in the transport device 200 to operate the transport device 200. The control unit 240 can include various sensors such as a tilt sensor, a speed sensor, an acceleration sensor, and a position notification sensor. In one embodiment, the control unit 200 can adjust the positions of the wheels 208 and 210 and / or the angular orientation of the cluster 212 to stabilize the transport device 200. The control unit 240 can also rotate the cluster 212 and wheels 208 and 210 to respond to input commands received from user interface 206. In one embodiment, control unit 240 adjusts the angle of cluster 212 with respect to platform 202 based on various sensor inputs to provide axles 242 and axles 244 and 246 of wheels 208 and 210 through cluster 212, respectively. Platform 202, approximately parallel to the surface in transit Can be held in an upright position. This orientation is preferred when the transport device 200 is operating in standard or enhanced mode. Various modes, such as standard mode and enhanced mode, will be described in more detail below.

FIG. 2D shows a modified embodiment of cluster 248 for the human transport device 200. In this embodiment, the cluster 248 includes a first wheel 250 driven by a motor (not shown). The command to drive the motor can be received from the control unit 240 (Fig. 2A). Cluster 248 can also include a second wheel 252 that is not driven by a motor. For example, the second wheel 252 may be a caster wheel fixed to the cluster 248. Although the drawings so far have been described so that the forward direction is from left to right, it should be understood that the cluster 248 in FIG. 2D may be oriented in any direction. That is, the powered wheel 250 may be the front wheel or the second wheel 252 may be the front wheel.

FIG. 2E shows an example of a transport device 200 including non-motorized wheels 254 fixed to the control unit 240 of the transport device 200. In this embodiment, in one mode of operation, the cluster 212 can be rotated so that the rear wheels 208 remain in contact with the surface, but the front wheels 210 do not contact the surface. Assuming no instability, the torque from the rotation of the cluster 212 will tilt the transport device 240 forward until the non-driving wheels 254 come into contact with the surface. This mode of operation would be preferred when the transport device 200 is operating on a smooth flat surface. In this orientation, it is only necessary to drive the rear wheels 212 with a motor, and therefore there is an advantage that the amount of power consumed by the transport device 200 can be reduced.

If the cluster 212 was rotated so that both wheels 208 and 210 mounted on the cluster were in contact with the surface, the non-driving wheels 254 would be lifted from the surface and the transport would become a four-wheel drive. An example of a transport device 200 in such an arrangement is shown in FIG. 2F. In Figure 2F, wheels 210 and 208 are in contact with surface 270. The non-driving wheel 254 rises above the surface 270. In this embodiment, the cluster 212 and platform 202 are approximately parallel to surface 270. The various embodiments of the human transport device 200 have been described in detail above. Note that the wheels 208 and 210 may be powered wheels, each driven by a separate motor. However, both wheels 208 and 210 may be driven by a single motor. Further, only one of the wheels may be driven by the motor. Furthermore, the transport device 200 has been shown only in side views. It should be understood that the components shown in the side view can be placed upside down on the other side of the transport device 200. For example, the transport device can include clusters on each side of the transport device 200. In one embodiment, the clusters may be fixedly connected to each other so that they move as an integral member. However, it is also within the scope of the invention to allow the clusters to rotate or otherwise translate so that the clusters operate independently of each other. Furthermore, it should be noted that the present invention is not limited to what is realized in the transport device described above. For example, some or all of the teachings contained in this description may also be implemented in transport equipment such as helicopters, aircraft, automobiles, off-road vehicles, mopeds, motorcycles and the like. Another form of transport device capable of carrying out the teachings of the present invention is shown in FIG.

FIG. 3 shows a person transport device 300 on which the user can stand. The transport device can include a platform 302 suitable for supporting a standing user person 304. In one embodiment, the movement of the device 300 can be controlled by tilting the person 304 in a desired movement direction on the platform 302. In this embodiment, the platform 302 is rotatably attached to the base unit 306. The base unit 306 can include a control unit 308 that can control the movement and possibly stability of the transport device 300. Base unit 306 also has wheels 312 And cluster 310 including grounding members such as 314 can also be included. The human transport device can also include a second user input device, such as a joystick 316, for receiving the desired movement command from the user. As shown in FIG. 3, the human transport device 300 includes both a tilted platform 302 and a joystick 316.

More specifically, the platform 302 or joystick 316 sends an input to the control unit 308 to allow the user to direct the movement of the transport device 300. In response to user input, control unit 308 can rotate one or both of the wheels (312 and 314) and cluster 310. The control unit 308 also holds the center of gravity 318 vertically above the footprint of the transport device 300, sometimes regardless of user input, the position of the cluster 310 and / or the position of the wheels 312 and 314. Can be adjusted. As shown in FIG. 3, the center of gravity 318 is displaced vertically upward of the cluster 310 between the axes of the wheels 312 and 314. In one embodiment, the control unit 308 maintains the center of gravity 318 above the center point 320 of the cluster 310. When the center of gravity 318 is located above the center point 320 of the cluster 310, the transport device 300 will be very stable.

For convenience, some of the following discussions will state that the position of the center of gravity is known. However, in some cases, the position is based on the estimated position. The system and method for estimating the center of gravity will be described later. Further, although the center of gravity is described as a reference quantity, it should be noted that the teachings of this description are not limited to that and may only consider other characteristics of the transport device in order to effectively stabilize the transport device. For example, instead of having to rely on estimating the position of the center of gravity, the pitch factor (discussed below) can be considered.

FIG. 4 shows a simplified form of the transport device 200 shown in FIGS. 2A-F. In this example, the transport device is operating in so-called "balanced mode" (other embodiments such as the examples from FIGS. 2A to F-3 can also be operated in balanced mode). In balanced mode (where the transport device is stationary), the control unit attempts to maintain a center of gravity 400 above the horizontal axis 402 through the ground wheel 404, based on various inputs. In this mode, almost all stabilization is done by rotating the ground wheel 404 to keep the center of gravity 400 vertically above the horizontal axis 402 of the ground wheel 404. For this, cluster 408 will be held in a fixed position relative to the bottom of platform 202. In the embodiment shown in FIG. 4, the cluster 408 is held in a nearly vertical position. (The cluster can also be held at other relative angles.)

Repeatedly, the transport device 200 in equilibrium mode controls the position of the platform 202 so that the center of gravity 400 is displaced to any position vertically above the horizontal axis 402 of the ground wheel 404 on which the transport device 200 rests. It works by doing. To allow movement, slightly displace the center of gravity 400 either forward or backward of the lateral axis 402 of the ground wheel 404 so that the device begins to fall in a controlled state in the "FORE / AFT" direction. Can be done. When the center of gravity 400 is displaced with respect to the lateral axis 402, the ground wheel 404 is driven so that the center of gravity 400 is essentially held in a position relatively close to but offset from the axis 402. In this way, the device does not tip over. The equilibrium mode of the transport device, as shown in Figure 4, is disclosed in US Pat. No. 5,701,965. In this embodiment of balanced mode, the cluster 406 will be locked in place and will not rotate to help stabilize the transport device 400. For this reason, in this embodiment, the equilibrium mode is generally a "wheel only" method of dynamically stabilizing the human transport device. It can be thought of as an approach).

In some cases, the human transport device will mostly assist the user or any other external aid. It would be desirable to go up and down the stairs without receiving any or at all. For this reason, some human transport devices develop the ability to climb stairs and operate in so-called "stairs" or "tilt" modes. Examples of such devices are shown in US Pat. Nos. 5,701,965 and 5,791,425. In staircase mode, the wheels can be "slaved" into the cluster. That is, the wheels can move only to rotate the cluster, not as a means of transportation.

Figures 5A and 5B show two examples of the relative orientation of cluster 500 of human transport equipment operating in staircase mode. When operating in stairs mode, the cluster 500 should have its center of gravity above either the rear or front axle, depending on which direction you are going down the stairs (ie, climbing or descending the stairs). Can be rotated. When the wheel 502 comes into contact with the front edge 506 of the staircase 508, the wheel is held pressed against the staircase. As the center of gravity moves towards contact point 514, the cluster 500 will begin to rotate upwards, as shown in FIG. 5B. When the cluster 500 rotates, the interlocking wheels 502 rotate with respect to the cluster 500 in response to the rotation of the cluster, so that the same points on the wheels are in contact with the stairs at the contact point 510. If the wheels 502 could be moved, the rotation of the cluster would cause the wheels 502 to move away from the stairs, causing the transport device to tip over.

The cluster 500 rotates (in this example, clockwise) until the second wheel 504 makes contact with the upper edge 512 of the staircase 508 at the contact point 514. This process is repeated until the transport device reaches the top of the stairs. In another embodiment, for example, if the transport device is crossing a large curb, the above process may only need to be performed once.

The system uses either clusters or wheels to effectively maintain the balance of the equipment. However, in some cases it has been found desirable to use both wheels and clusters to keep the center of gravity in a position that prevents the user from tipping over. For example, it would be desirable for the wheels and clusters to rotate simultaneously to hold the platform in an upright position as it passes through uneven surfaces.

For this reason, some embodiments of the present invention are directed to new modes of transport control. This new mode is referred to here as enhanced mode. In one embodiment, the reinforcement mode is such that the center of gravity is located above or very close to the transport device footprint (or the transport device frame pitch (or a function of frame pitch)). Control the operation and stabilization of the transport device by controlling both the wheels and clusters of the transport device (to meet other criteria, such as keeping the parameters within a given range).

FIG. 6 is a block diagram illustrating in detail possible operating modes of the human transport device. In one embodiment, the human transport device can include standard mode 602, balanced mode 604 and staircase mode 606. According to certain embodiments of the present invention, the transport device can also include enhanced mode 608. These various control modes are used by software and hardware housed within the control unit to perform device movement. Each mode allows the human transport device to operate according to different parameters. Note that the human transport device can also include other modes of operation. For example, a human transport device can include a mode for transitioning between modes and a mode for handling system failures.

The control modes and related software and hardware described herein can be included within a control unit, such as the control unit described above in connection with FIG. However, various parts of the software and hardware can also be used outside the control unit. For example, it may be desirable or necessary to place various sensors elsewhere to effectively control the operation of platforms, clusters, wheels, or human transport devices. it can.

Balanced mode 604 and staircase mode 606 have been described above, and for illustration purposes it can be assumed that the embodiment of FIG. 6 operates according to the above description. However, it should be noted that there are variants of balanced mode 604 and control mode 606 that can be fully incorporated into transport equipment operating under the various control schemes given in this description.

The term "standard mode" as used herein refers to an operating mode in which no dynamic stabilization occurs. In standard mode, the cluster and platform remain fixed to each other. For example, if the user is operating a human transport device with a chair-shaped platform (Figures 2A-F) in standard mode, the motor that controls the angle of the platform with respect to the cluster is held in place. When the transport device is climbing uphill, the platform tilts backwards. However, if the slope is too steep, the center of gravity of the system is located outside the footprint of the transport device, which can cause the transport device to tip over backwards.

In standard mode, the user has full control over the movement of the transport device. That is, the control unit is very sensitive to user input. In one embodiment, this can be achieved by applying a high gain factor (discussed below) to the input received from the user input unit. The user input unit can be a joystick or any other suitable input device operated by the user. The transport device can also include a tiltable platform that acts as a user input unit.

According to certain embodiments, the standard mode can include two submodes. The first submode will be performed on a system as shown in Figure 2E. In this submode, the non-driving wheel 254 can be fixed to the control unit 240 of the transport device 200. The cluster 212 can rotate about the rotation point 213, at least until the device tilts forward and the non-driving wheel 254 comes into contact with the surface. In this mode, power is supplied to the motor that drives the rear wheels 208 to move in response to user commands. In this way, the power supply to the motor attached to the front drive wheel (for example, wheel 210) of the cluster 212 is stopped, so that the power can be saved. For this reason, the standard mode in general, especially this submode, is particularly attractive when attempting to operate a transport device 200 with a limited power source (eg, a rechargeable battery) for an extended period of time. Also, in this mode, any type of stabilization provided by the transport device will be disabled in order to conserve energy. Also, since the non-driving wheels are caster wheels and can have high maneuverability, the turning radius in this mode will be minimized. Also, each wheel connected to each side of the cluster 212 may include its own wheel motor. By sending different signals to each of the wheels on either side, the transport device 200 will be able to turn in a circle. This can be achieved by applying positive torque to one wheel and negative torque to the other.

Another submode of standard mode is to rotate the cluster so that all four wheels are in contact with the surface and the non-driving wheels 254 are kept off the ground, as shown in Figure 2F. Including. In this submode, the transport device 200 can function as a four-wheel drive transport device. However, it is preferable that the wheels do not respond to user input commands in this mode so that the user does not confuse this submode of the standard mode with the enhanced mode described below.

As mentioned above, standard mode can hold the platform in a nearly constant angular relationship with the cluster. In this case, the motors that position the cluster with respect to the platform can be disabled in any of the submodes of standard mode.

Returning to FIG. 6, the user can make transitions between modes by selecting the options presented to the user on the user interface. The user interface can be provided, for example, on arm 204 (FIG. 2A) provided on platform 202. Alternatively, the mode transition can be performed automatically. For example, when the power supply is at a low level, the transport device can be automatically transitioned from balanced mode to standard mode in an attempt to save power or ensure safety.

The transport device can transition from various modes to another mode. For example, the transport device can transition from standard mode 602 to equilibrium mode 604 and back, as indicated by arrow 620. The transport device can also transition from equilibrium mode 604 to staircase mode 606 and back, as indicated by arrow 621. The transport device can also transition from standard mode to staircase mode 606 and back, as indicated by arrow 622. When the user selects mode transition from the user input device, the transport device can enter and exit enhanced mode 608 from standard mode 602, balanced mode 604 or staircase mode 606, as indicated by arrow 623. As described below, the enhanced mode can be more dynamic stable than any other mode of the transport device. Therefore, if the control unit determines that the transport device is unstable in the current operating mode, the transport device can automatically enter the enhanced mode.

According to some embodiments, when the cluster is nearly vertical, it is prevented from automatically entering enhanced mode. Unless some of the parameters of the transport device's current orientation are such that the transport device becomes unstable when the mode change is made, it will be possible to exit enhanced mode almost at any time.

As will also be described later, the enhanced mode can include a plurality of automatically switched submodes. Further, the enhanced mode can be smoothly and effectively switched between the submodes by the control switching and gain scheduling system and method described later.

FIG. 7A is a simplified side view of the transport device 700 that can operate in enhanced mode. It should be noted that the transport device 700 is given as an example only and does not limit the application of the enhanced mode operation described herein.

Transport device 700 includes platform 702. As mentioned above, this platform may be a chair-shaped platform as shown in FIG. 2A, or it may be a user-standing platform as shown in FIG. However, the description of the relative angle of the transport device in reinforced mode applies equally to any structure or other structure. For the following explanation, in FIG. 7A, the angle represented by the arrow pointing in the clockwise direction is a positive value, and the angle represented by the arrow pointing in the counterclockwise direction is a negative value. To measure. For example, the angle shown as φc (cluster position relative to gravity) is a positive angle and the angle shown as θ3 is a negative angle.

The center of gravity 704 represents the center of gravity of the entire system. This includes the payload of the transport device 700, the user (not shown) and any payload that the user appears to have (also not shown). Also note that the center of gravity is only given as an example of transport device parameters that can be obtained by estimation and / or test to determine transport device stability.

The control signal generated by the control unit 706 sets the center of gravity 704 to the foot pre of the transport device 700. Try to hold it above the Again, the footprint of the device can be defined as being between the end points of the cluster, more preferably between the horizontal axes 708 and 710 of the front wheels 712 and the rear wheels 714. These wheels can be attached to and part of cluster 716. In one embodiment, the center of gravity remains above the center point 718 of cluster 716 in enhanced mode.

Platform 702 can be supported by platform support 720. The platform height (H) used herein shall refer to the distance between the bottom of the platform 702 and where the seat support 720 is connected to the cluster 716.

The seat height H can be adjusted by changing the angle θh between the upper portion 722 and the lower portion 724 of the platform support 720. A motor can be provided at the pivot point 728 that rotatably connects the upper portion 722 and the lower portion 724. The motor can increase or decrease the angle θh between the upper portion 722 and the lower portion 724 based on the seat height command. This is convenient because it allows the user to ascend (or approach) eye level of the standing person. In one embodiment, the platform 726 and the upper portion 722 can also include a motor that sets the angle θs so that the bottom of the platform 702 is approximately horizontal, regardless of the orientation of the upper portion 722.

In another embodiment related to the description of US Pat. No. 5,791,425, which is disclosed in FIGS. 9-11 and incorporated herein by reference, platform holder 720 adjusts to the platform and to each other. It may be an articulated arm having upper and lower portions that can be made. This adjustment can be made by a powered drive located at contact pivot points 726, 728 and 730 (where the lower portion 724 is rotatably connected to the cluster 716). By connecting the powered drives to each other (eg by belt), the change in the position of one motor connected at pivot point 728 between the upper and lower parts is the angle θs between the platform 702 and the upper part 722. The bottom of the platform 702 can be made nearly horizontal by making the corresponding changes.

There are at least two reasons why seat height is important for the operation of the human transport device 700. First, the seat height H can be used to estimate the center of gravity 704 of the entire system. Also, the seat height will affect the speed at which the center of gravity moves with respect to the vertical axis defined by gravity (g). The higher the seat, the slower the center of gravity will move in response to disturbances. For this reason, seat height may be a variable that can be considered when controlling the dynamic stability of the transport device. For example, seat height may be an input that affects the magnitude of a particular gain factor (discussed below) used to control or otherwise stabilize the transport device.

The amount of the center of gravity 704 deviating from the vertical axis passing through the cluster 716 is called "frame pitch" in this description, and is represented by θ1 in FIG. 7A. This frame pitch can be a "rotational" pitch based on angular displacement. As shown, the vertical axis passes through the center point 718 of the cluster 718. However, it should be noted that in reinforced mode, the vertical axis can pass through any part of the cluster (eg, footprint) located between the wheels 714 or the horizontal axis through the center of the wheels 712. If it is desirable for the axis to pass through a portion of cluster 716 that does not pass through center point 718, the stabilization control process described below to take into account the distance that the vertical axis through cluster 716 is from cluster 716 center point 718. Will be changed.

The control purpose of placing the center of gravity 704 above the center point 718 of the cluster 716 is the transport device. Note that it may not be applicable to other modes of operation. For example, in equilibrium mode, the control objective would be to hold the center of gravity 704 in an appropriate relationship above the horizontal axis through one of the wheels of cluster 716.

As mentioned above, the position of the center of gravity 704 will be based on an approximation that depends on the seat height. The position of the center of gravity 704 will also be determined based on the rate at which the platform moves with respect to gravity. This ratio is called the pitch ratio in this description. For example, a mobile sensor (not shown) placed on the transport device 700 can detect a high rate of forward leaning of the system. This movement will, in some cases, displace the center of gravity 704 so that it deviates from the footprint of the transport device 700. Therefore, it will be necessary to move the footprint of the device in the direction of the pitch ratio with respect to the surface so that the footprint is located below the center of gravity 704.

Figure 7A also shows the control unit 706. The operation of the control unit 706 will be described later. The control unit 706 can include various motion sensors that determine the pitch ratio of the system and the like. The sensor is not limited to any particular type of sensor and can be, for example, an accelerometer, a position sensor, a "level" sensor, or the like. As can be easily understood, the pitch ratio can be determined empirically by differentiating the measured or estimated frame pitch θ1 with respect to time. The control unit 706 can also include motors mounted on wheels 712 and 714, as well as various hardware and software capable of controlling motors mounted on cluster 716. The control unit 706 can also include various control loops described below that act to stabilize the transport device 700.

In one embodiment, the cluster 716 can be rotatably attached to the control unit 706. Therefore, a change in the angular orientation of the cluster 716 with respect to the perpendicular will not cause the same change in the orientation of the control unit 706. In this explanation, the difference between the angle at which the upper part of the control unit 706 is displaced from the horizontal line (expressed by the control unit angle θc) and the angle at which the cluster 716 is displaced from the vertical line (φc, which represents the cluster position with respect to gravity) is relative. It is called the cluster position and is represented by the angle θc. The angle θc represents the angular orientation of the upper part of the control unit 706 with respect to the center of gravity 704.

Again, the overall purpose of the enhanced mode is to attempt to position the center of gravity 704 approximately within the footprint of the transport device 700. In some embodiments, the enhancement mode attempts to place the centroid 704 above the center point 718 of the cluster 716. This embodiment can be largely regarded as a stabilization attempting to place all four wheels of the transport device 700 on the surface with the center of gravity positioned vertically above the center point 718 of the cluster 716. When this condition is met, the transport device 700 is in a nearly stable position. It would also be preferable to hold the bottom of platform 702 approximately parallel to the horizon. If the bottom of platform 702 is approximately parallel to the horizon, the user will feel more stable and therefore more comfortable.

The longitudinal axis 740 of cluster 716 is shown with an angular displacement from the horizon. However, the bottom of platform 702 remains approximately parallel to the horizon. This condition will occur, for example, when the transport device 700 passes through an inclined surface. The angle between the cluster 716 and the lower portion 724 needs to be reduced in order to keep the center of gravity 704 in the footprint of the transport device 704. This reduction can be done by a motor coupled to pivot point 730 that rotates the cluster 716 counterclockwise and pushes the lower portion 724 forward.

As mentioned above, in some situations, if the amount of cluster displacement from the perpendicular is too small (ie, φc = 0), simply providing a cluster stabilization routine will not be enough to effectively balance the transport equipment. In some embodiments, the rotation of the wheels can also be used to help position the center of gravity above (or in a proper relationship with) the footprint of the device to maintain equilibrium. It was also found that balancing on two wheels could reduce the usefulness of the transport device. For example, balancing on only two wheels would make it difficult to navigate well on uneven surfaces. For example, when crossing a curb with such a two-wheeled device, the amount of torque that must be applied to the wheels to effectively lift the transport device directly upwards would be excessive. When all the torque is applied to raise the wheels in a vertical plane, the control required to hold the transport device in a nearly vertical position will be severely hampered.

According to some embodiments, the enhanced mode can handle this problem. Reinforcement mode utilizes both parts of the cluster equilibrium technique as well as the wheel equilibrium technique in an attempt to keep the center of gravity vertically above the area that defines the footprint of the transport device. Utilizing both cluster and wheel balancing algorithms provides a transport device that is inherently more stable than prior art as the transport device travels on uneven surfaces.

In one embodiment, this new enhancement mode can include several submodes. For example, the strengthening mode can include a wheel PD (proportional differentiation) mode, a wheel POC (pendulum-on-a-cart) mode, and a wheel balance mode (used as a label). The name you have is not intended to be restricted or descriptive). Each of these various submodes is applicable in different situations. In one embodiment, the invention transitions between these submodes, depending on the current operating characteristics of the transport device.

Given these objectives and the parameters (ie, angles) defined in FIG. 7A, the control unit can stabilize it as the transport device travels on many different types of different surfaces. In one embodiment, the control unit can include one or several control loops that provide a gain factor to help stabilize the transport device. In another embodiment, the control unit can include a different control architecture for each mode.

FIG. 8 shows an example of a control loop 800 that can be executed in the present invention. The control loop 800 can include, for example, a plant 802 including a motor and a plurality of sensors that monitor various parameters of the transport device. At least one, and in some cases some, parameters can be fed back from plant 802 to control loop 800. For example, the frame pitch 804 and pitch ratio 806 of the human transport device can be fed back. By multiplying each of the parameters by a gain factor (eg, gain factors 808a and 808b), a control signal (the output of adder 810) that is finally reapplied to the plant can be generated. The larger the value of the coefficient multiplied by a certain parameter, the greater the influence that the parameter has on the value of the control signal. Further examples of control loops that can be applied to transport equipment will be described in detail below (FIGS. 20 and 21).

With reference to both FIGS. 7A and 7B again, one way to model the operation of the transport device would be to model the system as an inverted pendulum rotating at cluster pivot junction 730. Of course, the system may be modeled in several other ways. The total energy (E) of the system (including potential energy and kinetic energy) is expressed as:

<maths num="1"><img id="000002" he="6" wi="49" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Where J is the frame inertia (including the transport device, user and payload), θ1 is the frame pitch, θ1'is the pitch factor (derivative of θ1 over time), and m is the frame mass. , G is gravity and L1 is the distance from the center of gravity 704 to the cluster pivot junction 730 (note that L1 is determined by the platform height H). This equation can be simplified as follows by using a small-angle approximation for the cosine.

<maths num="2"><img id="000003" he="6" wi="38" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

The transport device 700 is most stable when the total energy is zero. This happens in at least two cases. In the first case, the frame pitch θ1 and the pitch ratio θ1'are zero. In this case, the transport device 700 is completely stationary. In another case, the frame pitch θ1 is negative (Fig. 7B), while the center of gravity 704 is moving forward. If the center of gravity is moving forward at a pitch factor θ1'that is large enough to compete with the frame pitch θ1, then the total energy will also return to zero again. Therefore, it is desirable to determine the relationship between the frame pitch θ1 and the frame rate θ1'so that the above equation becomes zero. When the above simplified energy equation is set to zero, the following equation can be derived.

<maths num="3"><img id="000004" he="6" wi="35" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

This equation will be zero in one of the two cases. One is the pitch term θ1 (mgL1 / J)^1/2 Is added to θ1', and the other is when the pitch term is subtracted from θ1'. A positive solution means that the transport device is returning vertically, and a negative solution means that the device continues to tip over even though the total energy remains zero. Therefore, a positive solution is selected to determine the equilibrium indicator q0, which can be defined by the following equation.

<maths num="4"><img id="000005" he="5" wi="24" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

However, ωn is the natural frequency of the inverted pendulum (mgL1 / J).^1/2 be equivalent to. From the above, it is clear that the system is well balanced when q0 = 0. Fluctuations from zero to up or down indicate that the transport equipment is not perfectly balanced and various corrections must be made. As will be described later, the value of q0 can be used as a value to shift the transport device between the various submodes of the enhanced mode. Of course, values other than q0 can be used, depending on how the transport device is modeled.

Enhanced mode Again, one mode of operation of the transport device is the "enhanced mode". Reinforcement modes can be applied (but not necessarily) to increase the ability to traverse uneven ground such as slopes, gravel roads and curbs. Clusters and wheels are used together to provide dynamic stability. Reinforcement mode is also (or instead) balanced mode for some reason (ie, loss of traction, inability to roll wheels, etc.) Can be used as a way to regain dynamic stability when is unable to maintain stability.

Depending on the various states of the transport equipment, it will be necessary to perform different submodes within the enhanced mode. These submodes will be described below.

The first submode is called the wheel PD mode. The wheel PD is a mode that responds to a user's movement command, is statically stable, and can respond to gradual changes in the surface during passage. In wheel PD mode, the transport device will strictly follow user commands. In some embodiments, this will allow the user to climb the slope, turn in place, and overcome various obstacles such as small humps. The wheel PD controller will be characterized in that the transport device responds very well to user input when in wheel PD mode. This allows the user to tightly control the movement of the transport device. In one embodiment, this will be achieved by applying a high gain value to the user input command transmitted to the wheels. Applying a high level of gain to user input commands will allow the maximum amount of torque to be obtained on the wheels. However, due to this inherent rigidity of wheel gain, a sudden change in wheel acceleration (ie, a sudden start or stop) will tilt the center of gravity back and forth. As a result, the cluster will lift a pair of wheels off the ground when attempting to apply compensating torque to the system by rotating the cluster. When such torque is applied, the wheel PD is probably unsuitable. Therefore, the device will switch to the wheel POC mode of the second mode.

The purpose of the wheel POC is to stabilize the transport device so that all four wheels are on the ground and the center of gravity is above the cluster and between the two end points of the cluster. In this mode, both wheels and clusters are used to attempt to position the center of gravity inside the footprint. In this mode, the wheels use pitch information to translate the center of gravity to a position above the footprint. Commanding the wheels to place the center of gravity in the upper center of the cluster connection would sometimes not match the command given by the user. To adjust this, the gain or architecture used by the control unit in the wheel POC submode has a large influence on the pitch and pitch factor signals and a small influence on the user command. In general, the wheel POC submode will only work when the stability of the transport equipment becomes unreliable. For example, when large obstacles or bumps travel on a very severe surface, stability may become unreliable.

As will be appreciated by those skilled in the art, only rotation of the cluster will be effective in stabilizing the transport device when the center of gravity is located approximately in the center between the end points of the cluster. As the pitch error (ie, the amount by which the center of gravity displaces from approximately the center of the cluster) increases so that the center of gravity is above a pair of wheels, the effectiveness of the cluster decreases and is a major stabilization factor. It will be necessary to use wheels as a means. For this reason, the strengthening mode also includes a third submode called the wheel equilibrium submode. The purpose of the wheel equilibrium submode is to stabilize the transport device in the event of large pitch fluctuations and to return the center of gravity and clusters to the orientation in which either the wheel PD or the wheel POC submode is valid. As mentioned above, wheel PD and wheel POC may be more effective when the cluster is near horizontal. Wheel balance is similar to the balance mode of wheel operation, but also includes the ability to rotate the cluster.

Each of the above modes can be executed in a single control loop contained within the control unit. Various gain factors are applied to the control loop to achieve the above effects, depending on which submode of the enhanced mode the transport device is currently operating. The gain for each submode can vary, for example, the amount by which the user controls the transport device and the amount by which the transport device performs its own dynamic stabilization. Also, each submode can be executed as an individual control architecture. You can also do it.

As mentioned above, the transport device control unit can perform various gain or control architectures in the control loop to control and stabilize the transport device in enhanced mode. Some basic switching criteria must be established to know when switching between submodes of enhanced mode (and thus when switching gain or control architecture in the appropriate embodiment). In some embodiments, the quantity q0 can be used as a criterion for determining when switching between modes. For example, q0 can be used to switch between wheel PD and wheel POC. The value φc (cluster position relative to gravity) can also be used to switch from either wheel PD or wheel POC to wheel equilibrium mode. (Of course, in other embodiments, other parameters can be added or used instead.)

Switching between the various modes within the enhanced mode will depend on the cluster position φc with respect to gravity. FIG. 9 shows a graph display 900 of various values of φc. Again, φc represents the cluster position relative to gravity, and measurements are taken so that φc is zero at the vertical cluster position and φc is 90 ° at the horizontal cluster position. In the graph display of FIG. 9, the vertical axis 902 represents φc at 0 °, and the horizontal axis 904 represents φc at 90 °. In this embodiment, when the angle φc is close to 90 °, the transport device will remain on either the wheel POC or the wheel PD.

As shown in FIG. 9, the region where the transport device remains on either the wheel POC or the wheel PD is the region 906 located between the horizontal axis 904 and the ray 908. If the cluster angle φc with respect to gravity is below the line of sight 908, the transport device will remain on either the wheel POC or the wheel PD. When φc becomes higher than the value represented by the line of sight 910, the transport device shifts to vehicle equilibrium mode and stays there. That is, while φc remains in the region 912 between the vertical axis 902 and the line of sight 910, the transport device will remain in wheel equilibrium. However, there is a region 914 between the rays 910 and 908 where it is difficult to select the appropriate operating mode of this embodiment. In this region 914, various other factors will be considered to determine whether the transport device is in wheel equilibrium mode or in one of the remaining modes. If the center of gravity is approaching or above the footprint of the device, as determined by frame angle and pitch ratio, the transport device should shift to either wheel PD or wheel POC. However, if the center of gravity is approximately above any of the ground contact members, the transport device should transition to wheel equilibrium mode. Examples of angular values for the positions of rays 910 and 908 can be 30 ° and 60 °, respectively.

According to one embodiment, the transition from wheel PD to wheel POC and vice versa is determined based on the control switch value σ, where σ can be determined with respect to q0 by:

<maths num="5"><img id="000006" he="5" wi="37" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

However, A1 is a scaling constant, and LPF (q0) is the output of a first-order low-pass filter given an input signal of q0. φ'c roughly represents the smoothness of the surface during passage. For example, on an uneven surface, φ'c is large because the cluster orientation changes rapidly. Similarly, φ'c will be smaller on smooth surfaces. It has been empirically determined that A1 with a value of 1.66 is a valid value for some examples.

Hysteresis type determination when switching modes to prevent chattering between modes Can be fixed. For example, if σ is greater than or equal to the entry value (eg, 1), the transport device enters the wheel POC. The transport device will be in the wheel POC until the value of σ is less than or equal to the exit value (eg 0.5), which is the point at which the transport device transitions to the wheel PD. Of course, the entry and exit values will vary depending on the operating characteristics of the transport device.

FIG. 10 shows a data flow diagram of one embodiment in which the value of σ can be determined. The external inputs are the pitch ratio (θ1') contained in the data block 1002, the frame pitch θ1 contained in the data block 1004, and the cluster velocity φc'with respect to gravity contained in the data block 1006. At block 1006, multiply the frame pitch θ1 by the natural frequency ωn of the inverted pendulum. Addition block 1008 adds the output of block 1006 to the pitch factor received from data block 1002. The output of addition block 1008 is q0. Then, in block 1010, pass the value q0 through a low-pass filter. Then, in block 1012, determine the absolute value of the lowpass filtered q0 signal. Then, in adder 1016, pass the cluster velocity φc'of data block 1006 through a low-pass filter in block 1014, and then add the output of block 1012 to the value after determining the absolute value (in block 1020). To do. Next, the output of the adder 1016 is passed through the low-pass filter 1018, and the output of the low-pass filter 1018 is the value of σ according to the above equation.

FIG. 11 shows one embodiment of a flowchart of how to determine when to make a transition between submodes of enhanced mode based on φc and σ (in this embodiment). Of course, various switching criteria can be used depending on the method of modeling the transport device. Processing begins at block 1102, which receives the current values of φc and σ. At block 1104 it is determined whether φc is less than W Bon. The variable WBon represents the angular value of φc, below which the transport device must always be in wheel equilibrium mode. This is shown in FIG. 9 as the region 912 between the rays 910 and the vertical axis 902.

If φc is less than W Bon, block 1106 determines if the transport device is currently in wheel equilibrium mode. If the transport device is currently in wheel equilibrium mode, no further processing is required and processing returns to block 1102. However, if the transport device is not in wheel balance mode at that time, at block 1108, the transport device transitions to wheel balance mode and processing returns to block 1102.

If φc is greater than or equal to WBon, block 1110 determines if φc is greater than WBoff. The value of WBoff is the value of θc, below which the transport device must be in either wheel POC mode or wheel PD mode. WBoff is shown as ray 908 in Figure 9. If φc is greater than WBoff, processing proceeds to Wheel PD / Wheel POC Hysteresis Processing Section 1112. If φc is less than or equal to WBoff, it can be seen that the value of φc is in the region between rays 910 and 908 in FIG. 9 (eg, region 914). As mentioned above, in this region, if the center of gravity is close to one axis of the wheels of the cluster, the transport device must transition to wheel equilibrium mode. Therefore, at block 1114, it is determined whether the center of gravity is near one of the axles. If the center of gravity is near one of the axles, at block 1116 the transport device goes into wheel equilibrium mode and processing returns to block 1102. However, if the center of gravity is not near one of the wheel axes, the process enters the wheel PD / wheel POC hysteresis processing block 1112. As mentioned above, the position of the center of gravity is a convenient amount to consider when determining when to switch modes. However, it should be noted that the center of gravity is actually only an estimated position based on the operating characteristics of the transport device. For example, the center of gravity can be a representation of the frame pitch and / or pitch ratio of the transport device. These quantities (as well as others) can be determined from the position, velocity and accelerometer sensors that can be contained within the transport device.

Hysteresis processing block 1112 performs the above functions for transition between wheel POC and wheel PD based on the value of σ. Within block 1112, block 1118 first determines whether the transport device is currently in wheel POC mode. When the transport device is in wheel POC mode, block 1120 determines if σ is greater than 0.5. Since it has already been determined that the transport device is already in the wheel POC, the value of σ must be less than 0.5 in order to transition to wheel PD mode. Therefore, if σ is determined to be greater than 0.5 in block 1120, the transport device must remain in wheel POC mode and processing returns to block 1102. However, if σ is less than 0.5, at block 1122 the transport device transitions to wheel PD mode and processing returns to block 1102.

If at block 1118 it is determined that the transport device is not currently in the wheel POC, at block 1124 it is determined that σ is not higher than 1, then the transport device must remain in wheel PD mode. Processing returns to block 1102. However, if σ is higher than 1, at block 1126, the transport device goes into wheel POC mode and processing returns to block 1102. Note that the above switching values are only examples. These values will vary depending on the weight of the user, the weight of the transport device, the accuracy of the various sensors on the transport device, and so on.

The various switching processes described above can be performed by driving both the wheels and clusters of the transport device, with various stabilization controls within each mode. Each wheel may be driven independently by an individual motor. Alternatively, some wheels may not be driven by a motor, or two wheels mounted on a common shaft may be driven by a single motor. Also, the cluster can include individual motors.

The commands to control the wheels and clusters are expressed as voltages Vw and Vc, respectively, so that the transport is stable in any of the enhanced modes, regardless of the structure of the transport. That is,

<maths num="6"><img id="000007" he="12" wi="61" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

The voltage represents the voltage applied to the drive unit of the electric motor to generate the output torque. Of course, the drive unit does not have to be electrical, and in any case, a value other than voltage may be used. The variable X represents the horizontal position error of the transport device, and is the difference between the horizontal position of the transport device and the desired horizontal position of the transport device. The'(prime) symbol represents the time derivative. The coefficients K1 to K8 vary depending on which submode of the enhanced mode the transport device is operating.

An example of the relative values of the gain coefficients K1 to K8 used by the control unit in each mode is shown in Table A below. Depending on which gain is used, the control unit will control the transport device in various ways corresponding to the applicable submodes.

<tables num="1"><img id="000008" he="65" wi="131" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The relative strength and sign of each gain value listed in Table A is sufficient to distinguish each submode. In Table A, the value of ++ is greater than the value of +. The zero value does not necessarily have to be exactly zero, but rather can represent a very small value.

FIG. 12A shows a block diagram of a control unit 1200 that can be used in connection with the present invention. The control unit 1200 of this embodiment will control both the cluster and the wheels attached to the cluster according to the Vc and Vw equations described above. The main role of the cluster is to apply frame dynamics-based torque to gravity (ie, the cluster rotates to hold the platform at the desired pitch angle to gravity). In enhanced mode, the wheels should follow commands from the user, monitoring two criteria. If the cluster position with respect to gravity is changing (ie, the ground slope is changing) or q0 is large, by using balancing control instead of position / velocity control, the wheels will be out of user control. , Can be switched to help the cluster keep the frame upright. If the angle of the cluster to gravity decreases (ie, the cluster approaches a vertical state), the goal is to lower the cluster more horizontally while minimizing travel distance. This helps ensure that the user is comfortably supported on the transport device.

The control unit 1200 includes a wheel controller 1202 and a cluster controller 1204. The wheel controller 1200 can receive various inputs regarding the current operating characteristics of the transport device, as well as turn signal user inputs (eg, received from the joystick). From the input, the wheel controller 1202 can generate a wheel control voltage Vw that controls the wheel motor. The value of Vw allows the wheel motor to "drive" the transport device to advance the surface by applying torque to the various wheels of the transport device. As mentioned above, the transport device can include a motor for each wheel and can generate a separate value Vw for each wheel motor. In this way, the transport device can be operated by applying different wheel voltages to the wheels.

Cluster controller 1204 can also receive various location inputs, generally associated with transport equipment, along with cluster identification information. The cluster controller 1204 converts this information into the cluster motor control voltage Vc. The cluster motor receives this signal Vc and rotates the cluster around the axis.

In one embodiment, the wheel controller 1202 can receive input from data block 1206 from data representing the pitch (θ1) of the frame. The above data is reliable Note that it is stated as a value in. For example, the frame pitch is expressed as an angle value. However, any value used to control both directional control and stability of the transport device is expressed as an error term indicating how far a parameter is from the desired position, or in many other ways. can do. For example, the frame pitch can be expressed as a value in which the current frame pitch differs from the desired pitch. That is, the error signal will be equal to the difference between the current frame pitch and the frame pitch that places the center of gravity directly above the center point of the cluster. Also, although various angles are expressed in degrees here, each angle is a radian or a "count" (natural value) that is graduated to give the desired response when the transport device receives such a value. It can also be expressed by.

Wheel controller 1202 also frame rate (frame) from data block 1208 rate) You can receive instructions. The frame rate represents the rotational rate at which the frame is moving and can be represented as a time derivative of the frame pitch of data block 1208. Also, the rate at which frames move will depend on the height of the platform relative to the cluster. The gain applied to the frame rate input to give a more desirable response to the frame rate information to prevent the transport device and ultimately the user from tipping over when the seat is raised ( Can be changed (described later).

Wheel controller 1202 can also receive the current speed at which each wheel is spinning from data block 1210. This speed can be expressed, for example, in increments, but can also be expressed as ωwheels based on the turnover rate.

The wheel controller 1202 can also receive some input from a user input unit such as a joystick. Generally, these inputs are expressed as the desired wheel speed contained within the data block 1212. The desired wheel speed can include, but is not limited to, the desired direction of movement and speed of movement. Wheel controller 1202 can also receive an indication of the current wheel position from data block 1214. By comparing the desired wheel position obtained in block 1212 with the current wheel position on the wheel controller 1202, the differential speed and direction in which the wheels should be driven to respond to user input commands can be determined. The directional difference information allows different motors mounted on different wheels to swivel the transport device by receiving different wheel voltages Vw.

The cluster controller 1204 also receives the frame pitch from block 1206 and the frame rate from block 1208 received by the wheel controller 1202. Cluster controller 1204 also receives the cluster location from data block 1216. This cluster position is described as φc. Repeatedly, the cluster controller 1204 can attempt to rotate the cluster so that the center of gravity can be held above the footprint of the transport device.

Cluster controller 1204 can also receive cluster speed from data block 1218. Cluster speed is expressed as the rate at which the cluster rotates about the axis of rotation that passes horizontally through the cluster. This cluster rate would be a derivative of the time at the cluster location received from data block 1218. Both position and speed can be determined by suitable sensors contained within the transport device. Suitable sensors include, but are not limited to, accelerometers, speed sensors and position reporting sensors.

The control unit can also include a mode controller 1220. The mode controller 1220 can control the transition from various modes to another. The mode controller 1220 may be a separate controller, but may also be incorporated into one or both of the wheel controller 1202 and the cluster controller 1204.

The mode controller 1220 is currently capable of outputting mode 1222. The current mode can be based on the user selection mode received from data block 1224. The current mode also specifies a particular submode of the enhanced mode that the mode controller has determined to contain the transport device, based on any or all of the inputs received by the wheel controller 1202 and the cluster controller 1204. be able to. Also, the current mode is used by the control unit 1200 to determine the proper gain to be applied to the control loops present inside the wheels and / or cluster controllers 1202 and 1204, respectively, or which control architecture should be selected. Can be decided.

In one embodiment, the calculated voltages Vw and Vc can be used to drive the electric motor. However, other types of actuators such as hydraulic actuators and combustion engines may be used. In such an embodiment, control signals other than voltage can be calculated and supplied to the actuator according to the above equation or similar equations that can take into account various operating parameters of the actuator.

In an embodiment where an electric motor is driven using Vw and Vc, the voltage can be divided by the battery voltage to generate a duty cycle command to be sent to the amplifiers mounted on each of the wheel and cluster motors. it can.

FIG. 12B is a functional block diagram of the control unit 1200. The control unit 1200 includes a microprocessor 1250. The microprocessor 1200 can be connected to and communicate with the wheel control loop 1252 and the cluster control loop 1254 via bus 1256. The microprocessor receives various sensor inputs from the wheel control loop 1252 and the cluster control loop 1254, from which any of the quantities described in relation to FIGS. 7A and 7B can be determined. For example, the microprocessor can determine the pitch ratio of the transport device based on the data received from the speed sensors of either one or both of the wheels and cluster control loops 1252 and 1254. These decisions can be made, for example, by the software or hardware contained within the microprocessor 1250. In addition, the microprocessor 1250 can perform calculations to determine the position of the center of gravity and the desired orientation based on the position of the center of gravity, as will be described later.

The microprocessor 1250 can receive power from a power source 1258 (eg, a battery). In some embodiments, the microprocessor 1250 can determine the amount of power received by the wheels and cluster control loops 1252 and 254, depending on such things as the current operating mode of the transport device. Also, user input can be received from user input block 1260. These user inputs can be given by the control unit 1200 with varying amounts of consideration, depending on the particular mode of operation of the transport device, as described below.

FIG. 13 is a control loop 1300 including the control unit 1302. The control unit 1302 can be similar to the control unit 1200 of FIGS. 12A and 12B. In this embodiment, the control unit 1302 receives various inputs and outputs the wheel and cluster control voltages Vw and Vc.

Control unit 1302 can receive user input from user input data block 1304. As described above, these user inputs can be given by sensing the directional deviation of the joystick that functions as a user input device. The user input can also represent the tilt of the user on the tilt platform, as described above. Control unit 1302 also includes wheel motor 1306 and cluster motor 1308. You can receive feedback information from. Based on the operating mode, user-entered values, and information received from the wheel motors 1306 and cluster motors 1308, the control unit 1302 allows the wheel motors and cluster motors to change the relative positions of the wheels and clusters, respectively. The values Vw and Vc can be determined.

In some modes, it is desirable to prioritize user input over control of wheel motor current. An example of such a mode is the standard mode described above. In such a mode, the control unit 1302 provides the user input command with a high sensitivity selected from the gain table or a particular control architecture 1310. In this way, the user can have significant control over the transport device. However, in such a mode, the stability of the transport device can be reduced. In another mode, it may be desirable to increase the stability of the transport device. In such a mode, the sensitivity to user input is reduced to give the stabilization routine a higher sensitivity. In this way, the transport device can be further stabilized based on the control parameters that can be embodied by either the software or the hardware in the control unit 1310.

FIG. 14 shows an example of a gain table 1400 that can be used according to aspects of the present invention. The gain table 1400 can be for devices with three modes, i.e., first mode 1402, second mode 1404 and third mode 1406. In this embodiment, each mode can include three gain coefficients C1, C2 and C3. Note that the gain table 1400 in FIG. 14 is for illustration purposes only and does not reflect a suitable gain value. That is, the values and modes in FIG. 14 do not necessarily reflect the preferred coefficients of each of the various modes described above.

These coefficients are used by the control unit to increase or decrease the effect of certain inputs in some embodiments. For example, by multiplying the coefficient C1 by the position error term of the transport device, the effect of the position error term on the operation of the transport device can be changed.

In the example of FIG. 14, the factor C1 would correspond to the factor applied to the cluster position determined by the value received from the cluster motor. The value C2 will correspond to the coefficient applied to the wheel position value received from the wheel motor. The value C3 would be the coefficient applied to the direction vector received from the user input. In the gain table 1400, the larger the value assigned to a particular coefficient, the higher the priority that the input to which the gain applies will receive in the control system. For example, in the first mode, the value of the cluster coefficient C1 is 1. Having a low value, such as 1, would mean that the cluster location is less utilized in transport equipment stabilization in the first mode. The value of the coefficient C2 in the first mode is 3. For this reason, wheels are a more active part of the stabilization of transport equipment than clusters. Similarly, the value is shown to be 7 at C3 in the first mode. Such a large value of C3 means that the first mode responds very well to user input. For this reason, the first mode is a mode with less stability, and all the stability that exists is due to the rotation of the wheels, which matches very well with the response to the user's input. Therefore, the first mode will be a mode similar to the standard mode described above.

Similarly, the second mode follows user input well because the cluster gain is zero, the wheel gain is relatively small (C2 = 5), and C3 is a relatively large value (C3 = 6). This mode will also resemble a balanced mode in which the wheels are primarily responsible for the balance of the transport equipment and the clusters remain in a fixed position. Responsiveness to user input C3 is lower than in standard mode (ie, eg, first mode) because the wheels stabilize the transport device without being significantly disturbed by user input. However, in balanced mode, it is desirable to allow the user to pass through the surface while keeping the wheels balanced and nearly upright, so the user enters. The force is not set to zero.

The cluster and wheel gains of the third mode are set to levels such that the cluster position and wheel position are related to the stability of the transport device and are used for its automatic control. The user input gain C3 has been reduced to a very low level and the user still has some control over the transport equipment, but mainly stabilization is done automatically by the clusters and wheels. Such a mode can be enhanced mode, for example, when the transport device is determined to be relatively unstable. In such a mode, the cluster and wheels rotate so that the center of gravity of the transport device is maintained between the end points of the cluster.

Control scheduling As mentioned above, the enhanced mode controller can switch between various modes. One of the reasons for switching between modes is to stabilize the human transport device. During the transition between submodes, the gain supplied to the control loop within the control unit can be changed or the control architecture itself can be changed. However, sudden changes in gain or architecture will have a sharp impact on the operation of the transport equipment. This would cause the center of gravity to accelerate sharply, making the transport device uncomfortable or even unstable. Also, sudden control changes (either gain or architecture) will increase system wear. Therefore, some method for smooth mode transition is required. The systems and methods described herein for smooth transition between modes of system are effective in situations where a person transport device is controlled. Those skilled in the art will understand that the teachings on smooth inter-mode transitions are not limited to application to human transport equipment and can be applied to any multi-mode system that performs inter-mode transitions. There will be. Therefore, in the following description, it is referred to as a "system" instead of a human transport device. In some embodiments, the system is a system that includes feedback from the controlled device, but no feedback is required to control the scheduling described herein.

One method traditionally used to make a smooth transition between modes in other situations is to slew the gain from the first mode until the gain is the gain of the new mode. It was. For example, suppose the value of the gain K1 is 4 in the first operating mode. It is assumed that the gain coefficient K1 in the second mode is, for example, 10. Applying this new gain value directly would cause a sudden disturbance in the system when changing modes. Sudden disturbances will affect the operation of the system and make it unstable. Therefore, in the prior art, the gain value is slowly changed from 4 to 10 by repeatedly increasing the value of the gain coefficient (for example, K1). For example, the gain coefficient is 4 at time T0, the gain coefficient is 5 at time T1, and the gain coefficient is 6 at time T2, so that the gain coefficient finally reaches 10.

However, it has been found that such an operation takes too long for the gain value to reach the proper state in order to stabilize the operation of the system while responding to commit with the desired new mode. .. Also, the mode of the system may switch again before the gain changes through to the new value. In such cases, the system never truly reaches a new mode of operation and remains in quasi-mode between modes, which is unpredictable. Unpredictability will cause system errors that reduce the effectiveness of the system.

It would also be desirable to smooth system control commands even when the system is not mode-changing. For example, a large voltage discontinuity in the control signal received from the motor controller can damage the motor drive system.

Therefore, in one embodiment, a control command from the control unit is applied to the controlled device. Smooth before squeezing. Smoothing can be performed, for example, by a smoother arranged between the output unit of the control unit and the device controlled by the control unit. The smoother can be, for example, any form of filter that limits the rate at which the control signal changes, or an adder that adds an offset value to the control signal.

FIG. 15 is an example of a system that can be run to smooth the control signal before applying it to the controlled device 1502. The system can include a control unit 1504 that produces a control signal. The control signal is used to control the operation of the controlled device. The control signal will undergo abrupt changes in value for many reasons. An example of a sudden change in control signals may be due to a change in the operating mode of the system. The smoother 1506 can limit the rate at which the control signal ultimately supplied to the controlled device 1502 (ie, the output of the smoother 1506) changes.

The smoother 1506 is, for example, a filter, an adder that adds an offset value (possibly an attenuation offset value) to a control signal, a hysteresis control circuit, etc., but is not limited to them.

FIG. 16 is a block diagram of a method of smoothing a control signal. Processing begins at block 1660, where the value of the control signal is determined. The control signal can be generated by user input, control loop output, preset values, and the like. The value of the control signal can be in any type of unit, such as voltage, current, digital display of the value, analog signal, and so on.

After determining the control signal, the migration process is executed in block 1602. The transition process can include, but is limited to, smoothing the control signal, adding an offset to the control signal, determining the rate of change of the control signal, and determining whether the system has made a transition between modes. There is no such thing. In some cases, the transition process can include a step that does nothing to the control signal.

The control signal is processed by block 1602, all necessary changes are made to the control signal, and then the change control signal is applied to the controlled device system. The system can include a single controlled device or several controlled devices.

In one embodiment, the invention can include a system and method for making a transition between modes such that the transition is smooth and the transition between modes is near-instantaneous. In one embodiment, this is the last control signal (ie, the modified control signal) applied to the controlled device when the first coefficient is used and the unchanged control signal generated using the new coefficient. This can be achieved by instantly installing a new set of gain coefficients in the system, gradually attenuating the difference with. In another embodiment, the system changes the control architecture as the mode changes to allow the difference in control signals to be attenuated. How the offset (difference) is attenuated and added to the control signal will be described in detail later.

Figure 17A shows a block diagram of control loop 1700 configured to perform a gain scheduling operation for smooth intermode transitions. Control loop 1700 includes control unit 1702 that is part of the feedback loop. Control unit 1702 can receive user input from data block 1710. However, the control unit does not need to receive user input and can be fully self-regulating. The control unit can also receive the current operating characteristics from the control signal receiver 1712. The control signal receiver 1712 may be any device that responds to the input signal. For example, the control signal receiver 1712 may be an electric motor that rotates according to the level of the input control voltage. In this case, the control signal would be the control voltage.

The control unit 1700 can include a gain coefficient 1704 for the first operating mode and a gain coefficient 1706 for the second operating mode. These coefficients may be stored in a single gain table, or may be their own individual table. The coefficients may be stored on any computer-readable medium such as a floppy (registered trademark) disk, ROM, or RAM.

Based on the current operating mode represented in the current mode data block 1714, the selector 1708 can choose whether to apply the first mode factor 1704 or the second mode factor 1706. Selector 1708 selects the appropriate coefficients and applies them as control coefficients 1716 for control unit 1702. The control factor can represent, for example, the current mode gain factor applied to the operation of the human transport device.

More specifically, the control coefficients can be applied to various input values received from the user or from the control signal receiver 1712. The control factors can be used by the control subsystem 1718 of control unit 1702. The control subsystem 1718 can include various control loops in which the control factor 1716 can be applied to various inputs to generate control signals. For example, control subsystem 1718 can include the cluster and wheel controls described above.

The system can also receive offset values from offset data block 1720. The offset value was generated immediately after the last control command (ie, the last smoothed control signal) applied to the control signal receiver 1712 just before the system switched modes and the control factor was changed. It will be the difference in value from the control signal. The offset value is received by the smoother 1722 and the current control signal is iteratively added to the attenuated version of the value received from offset data block 1720. For example, if the smoothed control signal has a value of 100 just before the system switches modes and a control signal value of 10 immediately after the system switches modes, then the control loop 1700 is entered after the system switches modes. When first passing, the value of 90 is added to the control signal. The next time it passes through control loop 1700, it attenuates this value by a certain amount and adds it back to the control signal. This can be repeated until the offset value decays to be relatively close to zero. Note that the offset value can be either positive or negative, depending on the value of the smoothed control signal applied during the first mode and the new control signal generated at the start of the second mode.

Figure 17B shows a block diagram of another control system that allows for a smooth transition between modes. In this embodiment, the first mode includes the first control architecture 1750 and the second mode includes the second control architecture 1752. Each control architecture can generate different control signals that control the system in different ways. An input (1754) from a control signal receiver (not shown) is added to both control architectures. Switch 1756 chooses a first or second architecture to control the system based on the current mode. Similar to the above, the smoother 1758 adds an attenuation offset to give the smoothed control signal to the control signal receiver (not shown).

As described above, the controller scheduling technique enables smooth transition between control modes. The above explanation has been given with reference to the operation of the transport device in various forms. However, it will be easily understood that the teachings on control scheduling are applicable to any control system. For example, this form of controller scheduling can be used when controlling mode transitions for aircraft, helicopters, electric motors, hydraulic motors, combustion engines or jet engines.

FIG. 18 is a flow chart of a control scheduling process that can be performed on the feedback system to control the system. The process begins at decision block 1802, where it determines if the system mode has changed since the last time it passed through the process. If the mode has changed, block 1804 determines the offset value. As mentioned above, the offset value will be equal to the last control signal sent to the control signal receiver (FIG. 17) minus the first control signal generated after mode switching. However, the processing does not necessarily have to use the control signal first generated in the new mode, and may use the control signal generated at some point near the mode transition. After determining the offset value, block 1806 adds the attenuation offset value to the control signal. Various methods for generating the damping offset are described below.

At block 1808, the value of the smoothed output control signal is stored for later use. The process then returns to block 1802. If block 1802 determines that the mode has not changed, decision block 1810 determines if there is offset attenuation at this time. If the offset is being attenuated, it is preferred to add the attenuation offset to the control signal at block 1806. However, if the offset is not attenuated, processing continues at block 1808. It will be easily understood that it is not necessary to determine whether the offset is attenuated. In that case, if the determination block 1801 is omitted and it is determined in block 1802 that the mode has not been changed, the process proceeds directly to block 1806.

There will be several different ways in which the offset value can be attenuated. For example, you can multiply the value of the offset by a factor that attenuates it (for example, a value less than 1). This will generate a new offset value that is smaller than the previous offset value. Update this small offset value to the current offset value so that it can be sent to the smoother for addition to the next control signal. Alternatively, the offset can be attenuated by repeatedly subtracting a fixed value from the offset.

FIG. 19 shows different signals present at different locations in FIGS. 17A and 17B. Signal 1902 represents a control signal that is believed to be generated by the control unit. At time t0, the value of the control signal is y1. At time t1, the value of the control signal changes rapidly from y1 to y2. This change will be caused by the mode transition of the system. Signal 1904 represents an attenuation offset value that can be added to control signal 1902. At t0, the offset value is almost 0. At time t1, the offset value rises to the level of y1-y2. That is, of course, let y1 be equal to the value added to the system at time t1. The offset value decays over time and becomes almost 0 at time t4.

Signal 1906 represents the value of the smoothed control signal (ie, the smoothed control signal) applied to the system. The value of signal 1906 is equal to the value of signal 1902 plus the value of signal 1904. The signal 1906 is attenuated in the same manner as the signal 1904 until the time t2 when the control signal starts to rise. As the control signal 1902 rises, so does the signal 1906. At the time t3 when the control signal 1902 begins to flatten, the smoothed output signal 1906 begins to follow the decay offset signal 1904 again, and continues until the time t4 when the decay offset signal 1904 decays to almost zero. At time t4, the control signal 1902 and the smoothed output signal 1906 are approximately identical, as shown at point 1908.

System operation 20 and 21 show examples of control loops that control the position of clusters of transport equipment and wheels. Examples of these control loops can be used to stabilize a human transport device. Can be done. For easy understanding, control loops may be integrated into a single control loop that produces both cluster and wheel control commands. Also, various parts of these control loops can be omitted or added depending on the functional capabilities of the transport device. Moreover, one of ordinary skill in the art will readily appreciate that the various control blocks described in connection with FIGS. 20 and 21 can be performed with hardware, software, or a combination of both.

With reference to FIG. 20, wheel control loop 2000 includes frame control subloop 2002, wheel control subloop 2004, yaw control subloop 2006 and cluster speed monitoring control subloop 2008. The control loop of FIG. 20 is given for a single wheel. Specifically, the control loop can actuate the right wheel (RW) of the transport device. In some embodiments, one controller may be provided on each wheel of the transport device. However, a single control loop can also be used to control all of the wheels.

The frame control subloop 2002 generates a signal for stabilizing the frame by controlling the rotation of the wheels based on the reference frame-related value and the actual frame-related value. For example, if the frame is tilted forward because the transport device has fallen from a curb, the frame control subloop 2002 has a wheel motor that drives the wheels forward at high speed to hold the center of gravity above the transport device footprint. To be able to.

The wheel control subloop 2004 can be used to try to match the performance of the transport device to the desired user input. That is, the wheel control subloop 2004 allows the wheels to strictly follow user input. Also, the position of the wheels will be important when the main stabilization is in the wheel equilibrium mode and the equilibrium mode obtained by the wheels. Therefore, when the system is in wheel equilibrium mode, the wheel control subloop will be blocked from user input 2010.

A yaw control subloop 2006 can be performed to ensure that the transport device can turn. Based on the wheel motor speed difference and user input, the yaw control subloop 2006 can generate control signals that allow different wheel control voltages to be applied to each of the wheel motors.

The cluster speed monitoring control loop 2008 uses information about the kinematic state of the cluster to influence the behavior of the wheels. If the wheels of the cluster start to lift from the ground, the value of L2 (cosφc) (block 2078) multiplied by the lowpass filtered cluster speed (block 2080) is less than zero. In this example, the cluster speed monitoring control subloop 2008 will generate a signal to accelerate the wheels to hold the center of gravity above the footprint. L2 is the distance from the axle to the cluster pivot.

The wheel control loop 2000 can receive more user input 2010 from the user of the transport device. User input can be received, for example, from a joystick. User input 2010 includes the commanded FORE / AFT speed 2012 and the commanded yaw speed 2014. When the transport device is correcting the pitch of the device or is in the wheel balance submode, both the commanded FORE / AFT speed 2012 and the commanded yaw (YAW) speed 2014 are by switches 2016 and 2018, respectively. Will be blocked. The reason for turning off switches 2016 and 2108 during pitch correction and in wheel balance mode is that device stabilization is more important than the response to user input commands in both cases.

For example, a strengthening mode in which a pair of wheels are off the ground (see, for example, Figure 7A). The simplified model of the transport device in (see) shows the relationship in which the pitch acceleration is a function of the cluster and wheel torques τc and τw, respectively.

<maths num="7"><img id="000009" he="13" wi="96" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

However, L2 is the distance from the wheel axis to the cluster pivot, and rw is the radius of the wheel. The coefficient in front of the cluster torque τc is a good indication of how much the cluster affects the pitch. The greater the degree to which the transport device tilts from the balancing wheels, the greater the influence of the cluster on pitch correction. On the contrary, when the center of gravity is near the upper part of the rear wheel, L1sinθ1 L2cosφc, and the cluster torque coefficient becomes close to zero. The criterion for entering the wheel balance controller is the magnitude of the cluster torque coefficient. When this factor is small, wheel PDs and wheel POCs will not be as effective as wheel balance controllers that use wheels as the primary means of influencing pitch. There is also another situation where the cluster angle must be increased so that it is more likely that only one set of wheels is on the ground. For this reason, wheels are the main means of balancing transport equipment. Therefore, if the user input command is taken into account, the control loop does not try to take the user input command into account because the transport device becomes ineffective for the stabilization of the transport device.

Returning to Figure 20, the FORE / AFT speed command 2016 passes through the speed slew limiter 2020, which limits the amount of forward speed when the wheel balance does not pitch correct. For example, when the platform is in a high position, it may be desirable to reduce the speed.

The desired speed of each wheel can be determined by adding the commanded FOR / AFT speed 2012 to the yaw speed 2012 commanded by the adder 2022. This desired wheel speed is used by the wheel control subsystem 2004 to determine wheel speed error, wheel position error and wheel speed feed forward inputs. To determine the wheel speed error, the output of adder 2022 is combined with the current wheel speed at adder 2024. The wheel speed error is passed through the error limiting functional component 2026 and then lowpass filtered by the filter 2028. It then generates a portion of the wheel command by multiplying the output of the lowpass filtered wheel speed error by the wheel speed error gain constant 2030.

To determine the wheel position error, the output of the adder 2024 is integrated by the integrator 2032 and then passed through the error limiter 2034. Generate some of the all-wheel commands by multiplying the position error by the gain 2036.

The wheel speed feedforward value can be determined by passing the desired speed value (the output of adder 2022) through the low pass filter 2038 and then multiplying by the wheel speed feedforward gain value 2040. Wheel speed feedforward allows the control system to substantially estimate the motor voltage required for the commanded speed without processing large steady-state speed or position error signals.

The wheel voltage Vw is generated by sending each of the error signals generated within the wheel control sub-control loop 2004 to the adder 2042 and adding it to all other error determinations.

The wheel control loop 200 can also include a frame pitch parameter related sub-control loop 2002 that produces frame pitch error and pitch rate error. flame The pitch error is generated by comparing the current frame pitch with the desired frame pitch on the adder 2046. The desired frame pitch can be estimated based on the parameters of the transport device. In one embodiment, the desired frame pitch 2044 is a frame pitch at which the center of gravity can be located directly above the center point of the cluster. This desired frame pitch can be based on the position of the center of gravity as determined by the following description. Another part of the wheel command can be determined by filtering the difference between the desired frame pitch and the current frame pitch with a low pass filter 2048 and then multiplying by the frame pitch gain 2050.

The pitch rate error can be determined by comparing the current pitch rate with the desired pitch rate 2052 on the adder 2054. In one embodiment, the pitch ratio is 0, which indicates that the transport device is perfectly stable. Another part of the wheel command can be generated by filtering the difference between the current frame pitch and the desired pitch ratio with a low pass filter 2056 and then multiplying by the pitch ratio gain 2058. Both the frame pitch and the pitch factor error are given to the adder 2042.

A commanded yaw (YAW) velocity 2018 can be given to the yaw (YAW) sub-control loop 2006 to control the yaw error signal for the transport device. In the yaw speed control subloop 2006, the yaw speed error and the yaw position error can be determined. The difference between the commanded yaw (YAW) speed 2018 and the current yaw (YAW) speed (determined by the adder 2060) is passed through the limiter 2062 and the low pass filter 2064 to the output of the low pass filter 2064. The yaw speed control signal is determined by multiplying the yaw speed gain 2066. Similarly, the difference between the commanded yaw speed 2018 and the current yaw speed is passed through the integrator 2068 and limited by the limiter 2070. A yaw position command can be generated by multiplying the limit signal by the yaw position gain 2072. Both the yaw velocity command and the yaw position command are given to the adder 2042.

The wheel controller 200 also includes a cluster speed monitoring control subloop 2008, which is φc multiplied by the low pass filter cluster speed (the product of blocks 2078 and 2080 determined by block 2082) less than zero. If, it is blocked by switch 2076.

The wheel control voltage Vw is generated by adding all parts of the wheel command at block 2042. As mentioned above, this voltage is smoothed by the smoother 2086 in order to generate the smoothing voltage control signal Vws. The above Vws can be generated by passing the attenuation filter offset 2088 through the low pass filter 2090 and then adding it to Vw on the smoother 2086. Vws is sent to plant 2092. The plant can include both wheel motors and cluster motors, in particular to output the current frame pitch, current pitch ratio, right wheel (RW) speed, left wheel (LW) speed, cluster position and cluster speed. be able to.

FIG. 21 shows an example of the cluster control loop 2100. Similar to the wheel control loop, the cluster control loop 2100 can include a frame-related sub-control loop 2102 that produces frame pitch error and pitch rate error. This frame-related sub-control loop 2102 may be the same control loop as above, but may be a separate control loop maintained within the cluster control loop 2100.

Also, the cluster control loop can include a maximum cluster position subloop. This subloop receives the values of φc, stop angle, which is the maximum cluster angle available in enhanced mode. Take it off. If the cluster is at an angle greater than φc, stop angle, the cluster position controller is shut off by switch 2106. When switch 2106 opens, adder 2108 subtracts the current cluster position from φc, stop angle. Next, a part of the cluster position command can be determined by multiplying the output of adder 2108 (cluster position error) by the cluster position gain 2110.

The cluster control loop 2100 can further include a cluster speed sub-control loop that produces a cluster speed error. In the cluster speed sub-control loop 2112, the adder 2116 subtracts the current cluster speed from the desired cluster speed 2114. In one embodiment, the desired cluster speed will be set to zero. After passing the output of the adder 2116 through the low-pass filter 2118, it is multiplied by the cluster speed gain 2120 and then sent to the adder 2122. Then, by smoothing the output of the adder 2112 with the smoother 2122 as described above, the signal Vcs to be sent to the plant can be generated.

Example of using enhanced mode In one embodiment, the reinforcement mode is configured for use on uneven ground. In this embodiment, the transport device can use four ground wheels, all of which can be powered to increase traction on the FORE / AFT surface. An example of how the transport device operates in one example of enhanced mode is shown below.

Surface traffic Since both clusters and wheels can be used in the reinforced mode to stabilize the transport device, the reinforced mode can work well on uneven, uneven surfaces. In one embodiment, all four wheels can be driven by separate motors, and in such an embodiment the transport device can handle slippery surfaces well. For example, if the speed of one wheel increases significantly, the control unit reduces the amount of power supplied to that wheel until the speed of that wheel is similar to that of the other wheel.

Obstacle In some embodiments, the strengthening mode allows the transport device to cross obstacles such as curbs or stones. For example, when crossing a curb, the user commands the transport device to come into contact with the curb (using a user input device). The wheel position error term (see Figure 20) increases as the user continues to command the transport device to move forward, even when the wheels are in contact with the curb. As the error term increases, the torque applied to the wheels causes the front wheels to ride on the curb. When the front wheels rise to the curb, the clusters rotate to keep the frame pitch near zero. Depending on how fast the above operation is performed, the control unit will switch between wheel PD mode and wheel POC mode (depending on the rate at which the cluster rotates). As the user continues to drive forward to rest the rear wheels on the curb, the cluster rotates in the opposite direction.

In one embodiment, when climbing a curb of about 15.24 cm (6 inches) (for example), the cluster rotates and the transport device switches to wheel equilibrium mode. As the transition occurs, the wheels are driven in the opposite direction away from the curb to stabilize the transport device. This would be an effective way to remind the user that the curb they are trying to cross is too large and should be avoided.

To get off the curb, the user simply drives the transport device away from the curb. If done slowly, the transport device will be kept in wheel PD mode. When the user leaves the curb at high speed, the transport device goes into wheel POC mode until the cluster rotation becomes very large and at least all four wheels are on the ground again. Fall from the curb at high speed And, the larger the cluster rotation will occur as the transport device is put into the wheel equilibrium mode. The transport device then prioritizes its own control (ie, ignores user input commands) in order to drive the wheels forward enough so that the center of gravity is above the footprint of the device.

Estimating the center of gravity In the above explanation, the position of the center of gravity has been referred to from time to time. In some embodiments, the transport device will be a direct estimate of the position of the center of gravity. In another embodiment, the transport device will use the desired component orientation based on an estimate of the position of the center of gravity. For example, in FIG. 20, the desired pitch (eg, block 2044) compared to the current frame pitch (at block 2046) is a frame pitch that can be based on an estimate of the position of the center of gravity. That is, the desired pitch would be the frame pitch known to position the center of gravity above the footprint of the transport device when certain components of the transport device are in a constant orientation.

How the center of gravity of the device can be estimated to determine the desired orientation of the components of the device will be described in detail below. Although touching the center of gravity in the context of a human transport device, it will be readily apparent that the teachings of this description relating to the estimation of the position of the center of gravity are not limited to the estimation of the center of gravity for the transport device. Therefore, the following description will apply to any device that requires an estimation of the center of gravity, in addition to the human transport device. Such a device is referred to as a system in the following description.

FIG. 22A shows an example of a control loop in which a centroid estimate can be used. The control loop 2200 includes a control signal generator 2202 and a device 2204 having several components. The control signal generator 2202 generates a control signal that allows an actuator (not shown) contained within device 2204 to orient various components of device 2204. The control signal generator 2202 may be included in one of the components of device 2204. However, to make it easier to explain and to clearly show that the control signal generator 2202 gives the control signal to at least one actuator of device 2204 to change the orientation of one of the components, the control signal generator 2202 Is shown as a separate block. The control signal generator 2202 can be similar to the control unit (electronic equipment box) of the above-mentioned transport device.

The input to the control signal generator 2202 is the difference (ie, offset) between the current orientation of one of the components and the desired orientation 2206. The offset is the output of adder 2208, which subtracts the current orientation from the desired orientation 2206 to produce an offset value. The control signal generator 2202 receives an offset value and, based on the offset value, generates a control signal that allows the device to orient the components to reduce the offset.

FIG. 22B is a block diagram of a system that can produce values that represent the desired orientation of the components of the system. The desired orientation determiner 2212 receives several inputs and produces the desired orientation of the component as an output. The desired orientation will vary depending on the operating mode of the controlled system (data block 2213). In one embodiment, the desired orientation will be equal to the orientation of the components known (or calculated) to balance the system. This information will be contained in data set 2214. The data set can be roughly referred to as an estimate of the position of the center of gravity. That is, it can be assumed that the center of gravity of the device is at a specific position when certain components of the device are in a certain orientation. This is the same as the estimated value of the position of the center of gravity. The method of creating this data set 2214 will be described later.

The desired position-fixing device 2212 also receives the system's current mode 2213. Some systems There are different modes of operation in which the estimated value of the center of gravity can be used in different ways. For example, the device can be a human transport device that self-stabilizes to prevent the user from falling off the transport device. In such a system, an estimate of the position of the center of gravity would be used to control the transport device to balance it. With reference to FIG. 20 again, an estimate of the center of gravity can be used to determine the desired frame pitch for block 2046. How to determine and use this estimate will be described later.

FIG. 23 shows an example of a transport device in which the center of gravity 2304 is displaced above the rear wheel 2302. The center of gravity position 2304 would be an estimator representing the position of the center of gravity of the entire system, including the transport device, the user and all other payloads that the user has or is mounted on the transport device. The center of gravity 2304 can be positioned by the coordinate value θ3 with respect to the electronic device box 2305 and the length L1 with respect to the cluster axis 2306. In some embodiments, the angle θ3 will be the only variable used. In other embodiments, both θ3 and L1 will be used to estimate the position of the center of gravity.

As mentioned above, the electronics box 2305 (control unit) will include various sensors capable of measuring the orientation of the cluster 2308 and the electronics box 2305, such as pitch sensors. The orientation of the cluster 2308 can also be determined by integrating the output of the cluster speed sensor located on the cluster or in the electronics box 2305, or reported by the cluster motor.

The transport device can include a ground contact member 2302 (in this embodiment, a wheel) having a center point 2310. When the center of gravity 2304 is above the center point 2310 (or any other point on the grounding member that provides stability), the transport device is balanced.

In FIG. 23, the angle is measured so that the arrow indicating the angle pointing in the clockwise direction has a positive value. For example, the cluster position θc with respect to the electronics box would be assigned a positive value.

The angle θ3 is the angle between L1 and the electronics box 2305. The electronics box 2305 can include tilt sensors that determine the orientation of various components of the transport device. These tilt sensors can directly measure the angle θe of the electronics box with respect to the horizon. A controller (not shown) can monitor the angle of the cluster with respect to electronics box 2305. The distance L2 is the distance from the center 2308 of the cluster to the center point 2310 of the wheel 2302 in contact with the ground. L2 is a known parameter determined by the particular transport device in use. In one embodiment, L2 does not change during vehicle operation, but will change depending on the type of cluster used by the transport device.

When the center of gravity 2304 is above the center point 2310 of the ground wheel, one way to model the transport device is:

<maths num="8"><img id="000010" he="6" wi="59" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Is. Expanding and organizing the terms of this equation gives:

<maths num="9"><img id="000011" he="5" wi="89" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

By solving this equation, for example, the desired orientation (θe) of the electronic device box 2305 can be determined. Since L1 and θ3 are non-linear trigonometric functions and the processing power of the microprocessor in the electronics box 2305 will be limited, it is more efficient to avoid directly calculating θe using trigonometric functions. Would be the target. In such cases, a lookup table and curve fitting scheme are used to generate a correction value for θe. In order to perform curve fitting based on the equations that have been expanded and organized, the expansion equation can be simplified.

<maths num="10"><img id="000012" he="5" wi="69" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

And if you organize the terms,

<maths num="11"><img id="000013" he="5" wi="75" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

And here,

<maths num="12"><img id="000014" he="12" wi="44" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

And h is the platform height. Knowing the two values of θe, we can solve this equation for K1 (h) and K2 (h). Once the values for K1 (h) and K2 (h) are known, simple trigonometric calculations can be used to determine the values for both L1 and θ3. As mentioned above, given L1 and θ3, the position of the center of gravity is known (of course, in the case of a transport device, that position is based on a reference position that can be the center point of the cluster, which will be described later. Gives K1 (h) and K2 (h), and thus an effective way to determine the two values of θe used to determine L1 and θ3.

Alternatively, the angle of the electronic device box can be obtained as a function of the cluster angle φc with respect to gravity, which gives the following equation.

<maths num="13"><img id="000015" he="7" wi="70" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

To reiterate, when the transport device is modeled based on φc by the above equation, two values of θe are needed to solve L1 and θ3. Either the electronics box angle or the cluster angle can be used to estimate the center of gravity, depending on which mode of operation the transport device is operating. For example, when operating in staircase mode, it would be preferable to use an estimate of the desired electronics box angle based on φc.

FIG. 24 is a flowchart of an embodiment in which a reference data set that can be used to estimate the position of the center of gravity can be created. FIG. 24 will be described in relation to FIGS. 25A to 25C. There are at least two reasons to create such a reference data set. First, the data set can be customized for individual users. Second, the data set allows efficient calculation of the desired orientation of the components of the transport device, as described below.

The method begins at step 2402, where the components of the device (eg, the transport device) are configured in a particular arrangement and the orientation of the various components is recorded. For example, a cluster of transport equipment can be placed in the first orientation and this value can be recorded. FIG. 25A shows the possible first orientation of cluster 2502, which in this example is represented by θc = 0 because the electronics box 2504 and the cluster are parallel to each other. In addition, the seat height is recorded as an initial parameter. In one embodiment, the platform height will be as low as possible.

In step 2404, the transport device is moved to the first position. The first position can be a position where the center of gravity is placed above one of the wheels of the cluster. At this point, the center of gravity is unknown or unpredictable, but the center of gravity is on the wheels because the transport is balanced with little or no stabilization required by the person moving the transport. It is clear that it is above the axis.

After placing the transport device in the first position in step 2404, record at least one orientation of the components in step 2406. The components in which the orientation is recorded include, but are not limited to, the orientation of the electrical equipment box (θ3), the cluster position with respect to gravity (φc), and the seat height. Values in various orientations can be recorded by physically measuring the angle or by using a sensor in the electronics box. The sensor can be utilized by sampling data from the microprocessor or by reading the output of the sensor directly.

FIG. 25B shows the transport device in position 1. In this example, the center of gravity 2506 is located above the front wheels 2508 of the transport device. The angle θe of the electronic device box is a positive value and can be recorded.

At step 2408, the transport device is placed in the second position. Similar to the first position, the second position can be the position where the center of gravity 2506 is placed above the rear wheel 2510 of the transport device and the transport device is in a balanced position (see FIG. 25C). At step 2410, record the orientation of the components of the device in the second position.

For example, the above processing can be repeated by setting the initial cluster position in a different direction and repeating all of the above steps 2402 to 2410. In addition, the height of the platform can be adjusted each time the process is performed.

FIG. 26 is a graph of the result of repeating the process outlined above several times. When the center of gravity is located above the footprint of the device (ie, between the two wheels), the horizontal axis indicates the relative cluster orientation (θc) in radians and the vertical axis indicates the corresponding electronics box orientation (θe) in radians. It is shown by. Of course, it is possible to create a similar graph in which θe is related to φc. The first line 2602 represents the processing result for the lowest platform height, and the second line 2604 represents the processing result for the highest platform height. As mentioned above, these lines follow the above equation relatively strictly. Therefore, by using these lines as a look-up table, the two values of θe can be easily determined based on the cluster orientation. As mentioned above, these two values of θe allow L1 and θ3. Can be calculated immediately. In addition, curves are created for both the highest and lowest platform heights so that all desired electronics box orientations can be determined for all seat heights at all cluster positions. It was found that L1 and θ3 can be linearly estimated between these two values.

Seeing Figure 26 again, if the current cluster location is 2606, the two electronics box locations recorded are 2608 and 2610. This is illustrated graphically by lines 2612 (currently cluster location) and 2614 and 2616 (possible electronics box orientation). By using these two values of θe, linear interpolation can be performed for L1 and θ3.

The values of L1 and θ3 can be used in various ways, for example, depending on the mode in which the system is operating. For example, if the system is a transport device, the system can include balanced mode, staircase mode and enhanced mode, as described above. The desired orientation of the electronics box in enhanced mode is called thetaref_fourwheels. It can be solved for thetaref_fourwheels based only on the value of θ3. Seeing Figure 23, the equation that places the center of gravity above the center point 2310 of cluster 2308 is:

<maths num="14"><img id="000016" he="5" wi="18" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Is. Therefore, the desired electronic device box angle can be easily calculated simply by determining θ3. In some embodiments, this desired orientation can be used as the desired pitch value for block 2044 (FIG. 20).

When in equilibrium mode, estimates of the position of the center of gravity based on L1 and θ3 can be used to determine the electrical equipment box orientation (theta_balance) that places the center of gravity of the axle above the ground wheels. Given θ3 and L1, the equation

<maths num="15"><img id="000017" he="6" wi="74" file="JP5336546B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

By solving, the orientation of the electronic device box can be calculated. Although at least descriptive embodiments of the present invention have been shown above, it will be appreciated by those skilled in the art that various modifications and improvements will be within the scope of the present invention. Therefore, the above description is merely an example and is not restrictive. The present invention is only limited as defined in the claims and equivalents.