Speed limiting in electric vehicles

ES 2 394 660 T3

DESCRIPTION

Speed ​​limitation in electric vehicles

Invention sector

The present invention relates to the control of electric vehicles and in particular to the control and limitation of the speed of electric vehicles.

Background of the invention

A wide range of transportation devices and methods are known for the transportation of people. Typically, these transport devices are based on static stability and are designed to achieve stability in all intended placement conditions of their ground contact elements with a surface located below. For example, the vector of gravity acting on the center of gravity of a car passes between the contact points on the ground of the car's wheels and the car's suspension keeps all the wheels on the ground at all times, making the stable car. While there are situations (eg, speed increases and sharp turns), which cause conveyors, which are otherwise stable, to become unstable.

A dynamically stabilized conveyor, also known as a "balancing" conveyor, is a type of conveyor that has a control system that actively maintains the stability of the conveyor while it is running. The control system maintains conveyor stability by continuously detecting conveyor orientation, determining corrective actions necessary to maintain stability, and controlling wheel motors to take corrective action. If the conveyor loses the ability to maintain stability, for example due to component failure or lack of sufficient power, the driver may experience a sudden loss of balance.

For vehicles that maintain a stable base, the coupling between the steering control and the control of the forward motion of the vehicles is not a concern. In typical road conditions, stability is maintained by the wheels that are in contact with the ground throughout a turn. On a balanced conveyor, however, any torque applied to one or more wheels affects the stability of the conveyor. Coupling between steering and trim control mechanisms is the subject of US Patent No. 6,789,640.

US 2003/0231022 A1 discloses a method for estimating the instantaneous capacity of a battery and US 2004/0118622 A1 discloses a method for limiting the speed of a conveyor having a motorized drive device.

Document FR 2 756 51 discloses a method for regulating the speed of a car with electric drive when the car is driven down a slope.

Summary of the invention

The invention, in one aspect, comprises a computer controlled method for controlling the speed of a vehicle that is driven by an electric motor. The method involves determining the torque in steady state and a torque during acceleration and deceleration of the vehicle traveling on a surface located below. The method also involves controlling the speed of the vehicle based on the torque in steady state, the torque during acceleration and deceleration, the measured current of an actuator device generated by a vehicle motor drive device, that applies a couple of forces to at least one element of contact with the vehicle's ground for its movement on the surface located below. Control of vehicle speed is also controlled based on vehicle weight and payload, torque applied to the ground contact element, vehicle acceleration and vehicle speed.

In some embodiments, controlling vehicle speed involves determining an acceleration compensated average current. In some embodiments, controlling the speed of the vehicle involves determining the amount of actuator current required to accelerate or decelerate the vehicle. In some embodiment, the determination of the amount of actuator current required to accelerate or decelerate the vehicle is based on the vehicle speed and the slope of the surface below. In some embodiments, determining the acceleration compensated average current involves subtraction of the actuator current caused by the acceleration or deceleration of the vehicle's measured actuator current.

In some embodiments, the vehicle is a dynamically stabilized conveyor with a maximum allowable vehicle speed controlled by modulation of a lean component of the vehicle. In some

In embodiments, a lean controller modulates the maximum allowable speed of the vehicle based on the average current compensated for acceleration. In some embodiments, the method also involves lowering the maximum allowable vehicle speed if the regeneration current increases. In some embodiments, the method also involves increasing the maximum allowable vehicle speed if the regeneration current decreases. In some embodiments, acceleration and deceleration of the vehicle are achieved, at least, primarily by actuation of the motor-driven device. In some embodiments, vehicle speed is controlled when the measured current exceeds an overall current threshold. In some embodiments, the overall stream is based on the user's experience level. In some embodiments, the vehicle is a statically stable conveyor. In some embodiments, the vehicle weight and cargo are estimated. In some embodiments, the weight of the vehicle and the cargo are measured.

In another aspect, the invention presents a controller for controlling the speed of a vehicle having means of driving by means of a motor. The controller comprises a torque module that determines the steady-state torque and the torque during acceleration and deceleration of the vehicle traveling on a surface located below. The controller also comprises a speed module that receives average steady-state torque and torque during acceleration and deceleration of the torque module and issues a desired vehicle speed command (eg, a lean angle). The desired lean angle is based on the steady-state torque, the torque during acceleration and deceleration, the vehicle weight and load, and the measured current generated by a motor vehicle drive device applying a torque , to at least one element of the vehicle in contact with the ground for displacement on the surface located below, the torque applied by the motor drive device and the speed of the vehicle.

In some embodiments, the controller controls vehicle speed when the acceleration compensated average is below a threshold. In some embodiments, the controller includes a lean controller module for controlling the lean of the vehicle to modulate the speed of the vehicle based on the vehicle speed instruction (eg, desired lean angle).

In another aspect, the invention relates to a vehicle having an electric motor drive means. The vehicle includes a platform that supports a payload. The vehicle also comprises a ground contact module coupled to the platform that includes at least one ground contact element for moving on a surface located below. The vehicle also comprises a motor drive device to apply a torque to said at least one element in contact with the ground. The vehicle also includes a power source to drive the motor drive device. The vehicle also comprises a controller that limits the speed of the element in contact with the ground, based on the weight of the vehicle, the payload and the slope of the surface below.

In some embodiments, the vehicle comprises a torque module, which determines steady state torque and torque during acceleration and deceleration of the vehicle. In some accelerations, the vehicle includes a speed module that outputs a desired vehicle speed command based on the average steady-state torque, the torque during acceleration and deceleration, a measured current generated by the motor-driven device, the vehicle weight and payload, torque applied by the motor drive device, and vehicle speed.

In some embodiments, the vehicle includes a speed controller that controls vehicle speed based on vehicle speed instruction. In some embodiments, the vehicle in which the vehicle speed instruction is the desired lean angle of the vehicle and the speed controller is a lean controller that controls the lean of the vehicle to control the speed of the vehicle based on the lean angle. desired incline. In some embodiments, the vehicle is a dynamically stabilized conveyor and the maximum allowable speed of the vehicle is controlled by modulating an angle component of the vehicle.

Brief description of the drawings

The above characteristics of the invention will be more easily understood with reference to the following detailed description, with reference to the attached drawings, in which:

Figure 1 is a schematic illustration of a conveyor, as described in detail in US Patent No. 6,302,230, to which the present invention can be advantageously applied.

Figure 2 is a block diagram of a control loop for dynamically controlling the stability of a vehicle in the front-rear plane, for an illustrative embodiment of the invention.

Figure 3 is a block diagram showing sensors, power, and control in accordance with an illustrative embodiment of the invention.

ES 2 394 660 T3

Figure 4 shows a representative block diagram of the inputs and outputs that make up a bypass control in a system having an architecture to which the present invention can be advantageously applied.

Figure 5A shows a steering bar tilt device for a personal transporter control action, in accordance with embodiments of the present invention.

Figure 5B shows a tilt device by means of a steering bar with flexion coupling of the column position with respect to the ground contact module, for the introduction of a control action in a personal transporter, according to embodiments of the present invention.

Figure 5C shows another tie rod tilt device with separate handles for the introduction of a control action for a personal transporter, in accordance with embodiments of the present invention.

Figure 5D shows a rotary steering device for control action, in accordance with a personal transporter, in accordance with embodiments of the present invention.

Figure 6 is a block diagram of a mixer block for combining a swing control action and roll information, in accordance with embodiments of the present invention.

Figure 7 shows a personal transporter, in accordance with one embodiment of the present invention.

Figure 8 shows a schematic block diagram of a drift control system, in accordance with various embodiments of the present invention.

Figure 9 shows the functional relationship of the deviation according to instructions with respect to the inclination of the bar, according to an embodiment of the invention.

Figure 10 is a disassembled perspective view of a bar tilt pivot, in accordance with one embodiment of the present invention.

Figure 11 shows a view of a constant force torque bushing for providing centering torque to the bar around the tilt pivot of the bar, in accordance with one embodiment of the present invention.

Figure 12 is a plan view of a digital level for use with a human transporter, in accordance with one embodiment of the present invention.

Figure 13A is a plan view of the platform of a human transporter, with the pressure plate removed, indicating the placement of the foot force pressure sensors, in accordance with various embodiments of the present invention.

In Figure 13B shows two foot plates, for detecting the displacement of the driver's left foot and right foot, in one embodiment of the present invention.

Figure 14 is an illustrative diagram of an idealized offset conveyor device having a rigid wheel moving at constant speed on a flat surface.

Figure 15 is a block diagram providing details of a drive interface assembly.

Figure 16 is a schematic view of the motor control of the wheel during trim and normal travel, in accordance with one embodiment of the present invention.

Figure 17 shows the relationship between various speed limiting parameters for an exemplary compensated conveyor.

Figure 18A is an illustrative diagram of an idealized wheel moving at constant speed along a zero slope surface.

Figure 18B is an illustrative diagram of an idealized wheel moving at a constant speed along a negatively sloped surface.

Figure 19 is a block diagram of the motor drive module of one embodiment of the present invention.

ES 2 394 660 T3

Figure 20 is an electrical model of a motor, in accordance with an illustrative embodiment of the invention.

Figure 21 is a circuit diagram of a battery in series with a load, in accordance with one embodiment of the present invention.

Fig. 22 is a flow chart showing a method for estimating battery parameters in accordance with an illustrative embodiment of the invention.

Figure 23 shows the relationship between measured motor current and vehicle limiting speed for an exemplary compensated conveyor, in accordance with an illustrative embodiment of the invention.

Fig. 24 is a schematic view showing speed limiting of a conveyor controller, in accordance with one embodiment of the present invention.

Figure 25 is a flow chart showing the speed limiting operation of a conveyor controller in accordance with one embodiment of the present invention.

Detailed Description of Illustrative Embodiments

Embodiments of the present invention are useful in vehicles that use electric motors and drives as the sole or primary means of applying force / torque to the wheels of a vehicle, both for acceleration and deceleration for travel on a surface located by below. These vehicles are typically powered or consuming power when running forward. In some cases, when traveling down a sufficiently steep incline, the drive device may require the application of a reverse or regenerative torque in order to maintain a permanent speed without acceleration. Embodiments of the present invention are useful with compensated and uncompensated vehicles when powered travel and braking are achieved by the same vehicle component, eg, an electric motor. For example, embodiments of the present invention are useful with statically stable vehicles and dynamically stabilized vehicles (eg, dynamically stabilized balanced conveyors).

In electric motor vehicles, the amount of drive device capacity used for acceleration or deceleration limits the braking ability of the vehicle. Knowing how much of the drive device's capacity is used to accelerate or decelerate, or how much remains in reserve, allows the system to alter the motion of the vehicle to inhibit undesirable dynamic effects. Undesirable dynamic effects, such as reduced braking ability, can result in the vehicle traveling downhill compared to the vehicle traveling on level ground.

It can be said that a conveyor acts "compensated" if it is capable of operation on one or more wheels, but would be able to remain on the wheels if it were not for the operation of a control loop that controls the operation of the wheels. A compensated conveyor lacks static stability, but is dynamically compensated. A transporter can be advantageously used as a mobile work platform or as a recreational vehicle, such as a golf cart or as a delivery vehicle. Wheels or other ground contacting elements, which provide contact between said conveyor and the ground or other surface below and which support the conveyor minimally with respect to inclination during routine operation are referred to in this description as " elements in contact with the ground ”.

Figure 1 shows a compensated personal transporter indicated generally with 10 and described in detail with US Patent No. 6,302,230, as an example of a device to which the present invention can be advantageously applied. A person 8 stands on a support platform 12 and supports a handlebar 14 on a bar 16 fixed to the platform 12. A control loop may be arranged such that the leaning of the user results in the application of torque to the wheel 20 about the axis 22 by means of a motor drive device. Conveyor 10, however, is statically unstable and in the absence of actuation of the control loop to maintain dynamic stability, conveyor 10 would not be able to operate in its typical operating orientation. "Stability", as used in this description, refers to the mechanical location of an operating position with respect to which the system will naturally return if the system is disturbed away from the operating position in any way.

Different numbers of wheels or other ground contacting elements may be used in different embodiments of the invention, advantageously, as especially appropriate to different applications. US Patent Publication No. 2006/0108156 describes a balanced off-road vehicle in Figures 6 and 7. The off-road vehicle has two front wheels and two rear wheels. Each of the rear wheels is driven by its own drive device. Thus, within the scope of the present invention, the number of ground contact elements can be any number equal to or greater than 1.

Figure 2 shows a control loop 200 to dynamically maintain the stability of a vehicle (floor 208)

ES 2 394 660 T3 in the front-rear plane, so that the vehicle remains vertical. This control loop 200 requires the tilt state as an input value, that is, as a control action. US Patents 5,701,965 and 5,791,425 describe vehicles that can be operated using the control loop 200 of Figure 2. Vehicles require instantaneous state of tilt measurement for active control of vehicle stability. . Plant 208 of FIG. 2 is equivalent to the equations of motion of a locomotion system driven by a single motor. The torque applied to the wheels is indicated by T. Theta (Θ) identifies the front-back tilt (that is, the tilt angle), X indicates the front-back displacement along a surface with respect to a reference point, and a point on a variable indicates the differential of the variable with respect to time. The gain controls Ki, K₂, K₃ and K₄ differentiators 212 and 216, and adder 204 are used to achieve equilibrium. To achieve dynamic control and ensure system stability and to keep the system in proximity to a reference point on the surface, the torque T for the wheels in this embodiment is arranged to satisfy the following equation:

T = ΚιΘ + Κ₂Θ_γ + K₃X + K4X_{r (ECN υ}

The earnings values ​​Ki, K₂, K₃ and K₄ they depend on control loop settings, physical system parameters, and other effects, such as gravity.

The block diagram of Figure 3 shows a control system 31 for controlling a vehicle in accordance with an illustrative embodiment of the invention. In this embodiment of the invention, the control system 31 is used to control the motor drive devices and the drive devices of a vehicle, for example the trim conveyor 10 of Figure 1. Drive devices 331 and 332 control the left and right wheels of conveyor 10 respectively. The control system 31 has data inputs that include the user interface 361, the angle sensor 362 for detecting the front-rear angle, the wheel rotation sensors 363, and the angle speed sensor 364. Angle velocity and angle can be derived by using various sensors (gyroscopes or inclinometers) alone or in combination. The control system 31 may also contain a trim margin monitor (not shown) that combines information about current battery parameters with information about motor parameters to calculate a conveyor moment speed limit. The trim margin monitor is used to ensure, for example, that sufficient battery current is available when transients (eg road bumps) are experienced during vehicle use to maintain vehicle stability. If there are groups of wheels ( such as, for example, in figure 2 of the patent US 6,874,591), the drive device 341 of the set on the left and the drive device 342 of the set on the right are used to drive the left and right sets respectively.

In other embodiments, the control system 31 may have more than two wheel drives. Additional wheel motor drives can be used for a vehicle having more than two wheels, as shown in US Patent 6,874,591, Figure 2.

In other embodiments, the control system 31 may limit the speed of the conveyor to ensure that there is an adequate reserve of speed to maintain balance or to maintain a particular amount of acceleration or deceleration, as explained with respect to the figure. 17. It is desirable to conserve both torque and speed, the specific magnitude of which depends on various factors. The control system 31 may further contain a logic system to reduce the speed of the conveyor to avoid damage to the battery due to the generation of overvoltage, as explained with respect to Figures 20-23. An overvoltage situation can occur, for example, if the conveyor is provided with the ability to regenerate the battery during braking and when downshifting is performed when the battery is already fully charged.

The term "inclination" used in this description refers to the angle with respect to the local vertical direction of a line that passes through the center of gravity of the system and the center of rotation of a contact element with the ground that supports the system by above the ground at a certain time. The term "system" refers to all the masses that move due to the movement of the elements in contact with the ground with respect to the surface on which the vehicle is traveling.

The term "lean situation" used in this description encompasses both the lean in the forward-to-rear plane and the angular velocity of the vehicle (ie, Θ and Θ_Γ (or Θ) in which Θ_Γ is the change time of Θ).

A mechanism for providing user control action for a personal transporter drift control system is described in detail in US Patent No. 6,789,640. As described therein, a user mounted on a conveyor can provide a deflection control action for the deflection controller 402 (shown in FIG. 4) by rotating a deflection bar assembly.

Figure 4 shows the differentiation in the adder 401 of the current deviation value ψ with respect to the value of

ES 2 394 660 T3 desired deviation vised to obtain the current deviation error ψ_{θ (7}-. The desired offset value ^ desired is obtained from a user control action, various embodiments of which are described herein. The current value of deviation ψ is derived from various state estimates, such as wheel speed differential, inertial detection, etc. The derivation of the deviation instruction, from the deviation error, is provided by the motor controller 405, in accordance with various process algorithms described, for example, in US Patent No. 6,288,505, and applied to left and right engines 403 and 404, respectively.

One of the key properties of a good steering control device is its ability to provide directional control action, while controlling lateral acceleration. Turns with high lateral acceleration require the user to lean into the curve to avoid falling or tipping on the conveyor. An optimal directional control device requires the user to have a well-positioned body when sending a directional control action. A deflection control action by means of a rotating bar, as explained above with reference to US Patent No. 6,789,640, favors the proper positioning of the body by orientation on its axis of rotation and the design of the combination of button and bar. It is possible, however, to perform an uncoordinated control action depending on the driver's technique.

Another method of promoting proper body positioning is to convert one or more steering rods into a joystick. By pivoting the bar near the base of the apparatus, the user can move their body at high speed and merely hold onto the control bar and command a control action. When properly arranged, the user's body is already in position to react against lateral acceleration at the start of the turn, reducing the likelihood of an improperly coordinated turn.

On the tilt tie rod apparatus, the control action for tilt is proportional to the angle of the tie rod relative to the frame. Preferably, the pivot axis is mounted as low as possible on the floor contact module of the conveyor, in order to allow the movement of the bar to naturally follow the movement of the user's body, since people are incline more stably by pivoting at the ankles. In other words, a low pivot control rod follows the kinematics of the body. In this embodiment, the deviation control action is converted to a deviation instruction using standard personal transporter algorithms, which apply a fixed gain to a low speed deviation control action, but scale the gain at a higher speed. raised to make the deviation control action corresponding to the lateral acceleration instead of the deviation speed. This works well with the tilt control bar tilt feature, as the desired tilt angle is roughly proportional to the bank. The result is a very natural control action method, in which the user "thinks" to the right or left by tilting and the apparatus tracks.

<img file="ES2394660T3_D0001.tif" />

(ECN. 2) where K is a constant;

Φηβ is the angle of the steering rod with respect to the platform;

Φκο // is the inclination of the platform with respect to gravity;

Ψοπκί is the deviation instruction.

Other embodiments of the invention may have a pivot control bar mounted inclined or horizontally. In apparatuses with inclined pivots, the angle of the pivot with respect to the place and contact surface provide interesting turning dynamics. Specifically, the axis of rotation can affect turning dynamics on a slope or on a flat surface. Preferably, the apparatus has a horizontal pivot in a low position. A horizontal pivot can easily follow the kinematics of a body during a turn.

In accordance with other embodiments of the invention, with the direction of travel as the reference point, the pivoting steering bar can be mounted at the front or at the rear of the conveyor. The rear-mounted pivot steering bar configuration enables the user to steer the conveyor with other parts of the body, such as the knees, in addition to using a leg applied to the steering bar. Additionally, the conveyor may include a feature that disables the tilt control when the user assembles or dismounts from the apparatus. The feature can be activated when the conveyor determines that the user is partially on / off the platform, so that the conveyor cannot turn towards or away from the user, while the user is mounting or dismounting the apparatus.

Of the different mechanisms suitable for providing the tilt of the steering rod, the first one is described with reference to Figure 5A. The movement of the steering bar 500 is limited to a plane that is substantially transverse to the direction of advancement of the personal transporter 10 by means of parallel link bars 502 that are pivotally coupled to both the

ES 2 394 660 T3 platform 12 as to the steering rod 500. The movement of the steering rod may be forced to a central position and / or damped by means of springs 504 or dampers. In an alternative embodiment shown in Figure 5B, the steering bar 500 is coupled to the platform 12 of the conveyor 10 by flexing elements 508, again reducing the movement of the steering bar substantially to a plane transverse to the direction of movement of advance and allow the tilt of the steering bar according to an arc centered on a virtual pivot point located in or near the plane of the platform 12. In any of the embodiments of Figures 5A and 5B, one or more detectors 510 detect the position of the steering rod 500 or members 502 that couple the steering rod to the conveyor, relative to vertical or relative to a direction. fixed with respect to the ground contact module. Sensor 510 may be a load cell, for example, disposed along a vehicle control axis (eg, bar 16 of FIG. 1). In addition, springs or dampers attached to the steering rods could be used to limit the rotational speed of the conveyor if desired.

In one embodiment, the movement of the steering rod is not forced to a central position. In embodiments where the steering rod is not forced to a central position, there is no preload around the axis and therefore the user can steer the conveyor precisely and accurately.

According to one embodiment shown in Figure 5C, two separate tie rod segments 520 and 522 can be moved separately, by tilting the user 8 relative to the conveyor platform 12. In the embodiment shown, the position of each tie rod segment is forced to a specific height "neutral" with respect to corresponding sleeves 524 and 526 by means of springs or otherwise. A relative height offset is transmitted to the offset controller for turning control, as described in connection with other modes of user control actions.

In another embodiment of the invention shown in Figure 5D, the clockwise and counterclockwise rotation 530 and 532 of the steering rod 500 with respect to a support column 16 is detected to generate a signal that transmits a user control action to a deflection controller (eg, deflection controller 402 of FIG. 4). A damper 534 is preferably disposed in pivotal engagement of the steering rod 500 about the axis 16.

One issue that must be taken into account in controlling the tilt of the steering bar is the effect of terrain sensitivity. If the apparatus is driven over obstacles or uneven terrain, a roll disturbance is imposed on the apparatus / driver system, since the resulting change in position of the user may cause an unintended drift control action in the system. Drift control modes that depend on the general inclination of the body of a standing person are likely to be more sensitive to terrain than, for example, drift control by means of a rotating bar.

To counteract this roll sensitivity, a roll compensation algorithm can be used. In this algorithm, the roll control action is modified to compensate for the frame roll angle, making the roll control action be the angle of the steering rod with respect to gravity. Since it is easier for the user to maintain the position of the body with respect to gravity rather than with respect to the platform, this makes it easier to compensate for sway disturbances.

In accordance with certain embodiments of the invention, a method for reducing terrain sensitivity uses an algorithm to filter deviation control actions based on frame roll speed. The instantaneous roll speed at which it is designated as Roll Speed ​​can be easily obtained from the Pitch State Estimator, such as that described, for example, in US patent no. 6,332,103, which deduces the orientation of the protractor based on one or more gyroscopes, an inclinometer, or combinations of these. Large roll transients cause the driver to accelerate and if the roll transients had to be rigidly coupled across the conductor to the yaw control mechanism, they could cause an unintended yaw control action.

There are two different parts to the solution: reject the action of the terrain while driving in a straight line and reject the action of the terrain while making a turn; the former is a special case of the latter, while deflection is disabled during periods of high roll speeds could solve the problem for motion in a fixed direction, more control actions are needed to decouple roll from directed motion.

An unknown control action is an estimate of the deflection control action "attempted" by the user (eg, the intention of the user to turn in a 20 '(6.1 m) diameter circle). Although the information on the attempted deviation control action is not directly available, it can be usefully inferred from the history of the deviation control actions. Simply low-pass filtering the data provides an estimate of the drift control action. However, this causes a response delay that is sensitive to the user. On the other hand, if only low-pass filtered data is used when high roll speeds are present, the driver will be less likely to notice the delay. The algorithm, therefore, according to one embodiment of the invention, uses a

ES 2 394 660 T3 rocking speed controlled mixer between direct deviation control action and a heavily filtered version.

A transfer function models the magnitude of the roll velocity that is coupled into the deflection signal. It is a function of several factors, including the design of the drift control action, the skill of the driver, and the manner in which the driver maintains the drift control action (eg, bar 16 in Figure 1). Using this mixing method, the transfer function can be largely ignored or minimized to the maximum degree through refinement.

Four main tuning points are: how quickly the mixer switches to the filtered version, how quickly the mixer returns, at what threshold the mixing starts and ends (“mix”), and the corner frequency (“corner frequency ”) of the low-pass filter (LPF) in the deviation control action. There are limits to the amount of uncontrolled drift that can be eliminated due to the mixing threshold setting. By setting it high, there is more uncontrolled drift, setting it low, there are more spurious offsets and the driver begins to experience the time delay in the drift signal. The LPF frequency setting has compromises as well. If the drift is over-filtered, then there is a noticeable delay and a possibility that drift transients will mesh from the past. Setting too low reduces the ability of the mixer to eliminate transients.

Referring to Figure 6, the mixer block is defined as follows:

Deviation Instruction = F * Deviation Control Action + (IF) * Filtered Deviation (ECN. 3) where F is the mixer function, which is a continuously varying signal between 0.0 and 1.0. Low pass filtering of the Filtered Roll Rate is advantageously facilitated so that scrolling over an uneven surface does not result in an erratic deflection response.

Figure 7 shows a compensated personal transporter, in accordance with embodiments of the present invention, and indicated generally at 10. Prior compensated personal transporters have been described in detail, for example, in US Patent No. 6,302. 230. A user (not shown) stands on a support platform 12 and holds a bar 14 on a steering bar 16 attached to the platform 12. The conveyor 10 also comprises at least one element in contact with the ground, the wheels 20 in this embodiment of the invention. The conveyor 10 also comprises at least one actuator device (not shown) located on the platform 12 that applies a couple of forces to the ground contact element to propel the conveyor relative to a surface.

The steering rod 16 may be referred to as a "steering column," "member," or "column," the terms of which are used interchangeably in this description. In this embodiment of the invention, the support platform 12 comprises separate left foot plate 18 and right foot plate 19, as will be explained later.

A control loop is provided, such that the forward or backward leaning of the driver results in the application of a certain torque to the wheel 20 about the axis 22 by means of a drive motor (not shown) as shown. explained in this description, thereby causing an acceleration of the conveyor 10. The control loop is implemented with a controller (not shown) located on or in the conveyor 10. The controller comprises at least one processor and inserts and withdraws for the control operation of conveyor 10. However, conveyor 10 is statically unstable and in the absence of control loop operation to maintain dynamic stability, conveyor 10 is unable operating in its typical operating orientation.

Figure 8 shows a block diagram of a deviation feedback control system, according to one embodiment of the invention. The deviation control action 80 is derived from a user interface, as explained below. A user's preferred control action is facilitated by the position of a member, by way of example, bar 16 (shown in Figure 7), about a register pivot axis indicated z.

It will be understood that while in a preferred embodiment the user facilitating the deviation control action is the driver aboard the personal transporter, the invention is not limited in this regard. For example, in an alternative embodiment, the deviation control action is facilitated by changing the position of the bar 16 by the user, while walking alongside or in front of the conveyor 10.

The LateralAcceIScale 82 function reduces the effect of the offset control action 80 for higher wheel speeds and greater centripetal acceleration. The feedback 84, used to regulate the commanded speed of deflection, contains a position term 85 of the deflection to maintain the deflection position, a velocity term squared 86 intended to regulate the deflection speed to zero, and a term of forward feed 89 intended to provide a better response to the user of the instruction of

ES 2 394 660 T3 deviation.

The forward advance term 89 predominates for quick maneuvers to provide a responsive system. Velocity square feedback 86 is an example of deviation from linear control theory and has the effect of providing non-linear deviation velocity damping.

The rate of change in a variable associated with the deviation control action (such as the angle of the Λ steering bar around the z-reference axis, typically the conveyor roll axis, as explained below), it can also be used as an additional deviation instruction and can be deduced using differentiator 81. The rate of change of the deviation control action variable 80 creates a component of the deviation instruction that "anticipates" the driver's lean and is more likely to keep the steering bar 16 coordinated with the driver and makes perceive the most sensitive transporter 10.

The gain 87, associated with the rate of change component of the deviation control action can be varied, for example, based on the user's experience level. In this way, the deviation instruction signal is generated based on the position of the steering rod 16 and the rate of change of the position of the rod 16 which is weighted based on the experience level of the user. In one embodiment, the value of gain 87 for an expert is set to 130% of the value associated with a beginner. Different gain values ​​can be implemented in alternative embodiments of the invention. In some embodiments, the conveyor can be configured to allow the user to apply multiple levels of expertise.

In some embodiments, the rate of change of the position of the bar 16 is weighted in response to the selection or specification by the user of a level of knowledge or experience of the user, for example, varying between beginner, intermediate and expert as modalities. of conveyor 10. Each mode may impose a different specified operating limitation on conveyor 10. In some embodiments, the user selects the mode through the use of controls or buttons located on the conveyor 10. In some embodiments, the user selects the mode by using buttons located on a control device (not shown) in some embodiments. , the rate of change of the position of the bar 16 is weighted to reduce its effect on the deviation instruction signal for a beginning user. In some embodiments, the rate of change of the position of the bar 16 is weighted to increase its effect on the offset instruction signal for an experienced user. Therefore, for beginners, the term of rate of change is advantageously reduced or eliminated, passing the deviation instruction predominantly or exclusively in the variable of deviation control action, such as angle

Λ of the tie rod around the z reference axis.

In addition, the rate of change component can be filtered with respect to frequency, so that the deviation instruction can be tailored to be more or less sensitive to rough maneuvers by more experienced drivers and more tolerant of abrupt maneuvers by less trained drivers.

In some embodiments, the user experience level is used to provide different operational characteristics for a conveyor, depending on whether the user is a beginner or an expert. In this way, low speed sensitivity and maximum controlled deflection speed can be reduced for a beginner mode, while maintaining steady state operation on a conveyor operating in expert mode.

Furthermore, in some embodiments of the invention, different control gains are used to control the operation of the conveyor for a beginner mode versus an expert mode when, for example, the conveyor is operated in reverse and / or during assembly and disassembly of the conveyor platform.

Various alternative modes for specifying user speed or direction control actions are described in US Patent Application Serial No. 10 / 939,955. A preferred technique for receiving deviation instruction input based on the tilt of the steering rod is disclosed in said document and various embodiments for implementing tilt of the steering rod are shown in Figures 5A-5D. .

The mode of tilt of the steering rod, in some embodiments, the deviation control action is proportional to some function of the angle of the steering rod with respect to the frame, in the case that said functional dependency can be changed in based on specific operating circumstances. Alternatively, the drift control action may be proportional to some function of the steering rod angle relative to a device independent system, such as relative to the local ground / inertia reference system (i.e. local vertical vector - local gravity vector).

A preferred relationship of the tilt of the tie rod to the controlled deflection is shown

2 394 660 T3 in Figure 9. In the relationship shown, the controlled deflection increases faster than Λ linearly with respect to the angular displacement (deflection) of the bar 16 about the pivot axis z.

Referring again to Figure 7, alternative embodiments of the invention are described in which the user facilitates a deflection control action by rotating the bar 16 about the pivot axis z, the pivot axis being the roll axis of the conveyor 10, so that the rotation of the bar takes place in a lateral plane with respect to the forward movement of the conveyor. An exploded view of a pivot assembly 100, around which the bar 16 rotates, is shown in Figure 10.

Axis 102 is aligned along pivot axis z (see Figure 7). Shaft 102 passes through bearing assemblies 104 and is supported by bearing assemblies 104, so that shaft 102 is rotatable about pivot axis z with respect to extrusion 106 of the base and bushing. rack 103. Base 106 is coupled to platform 12 of conveyor 10 of FIG. 7.

The orientation of shaft 102 and therefore bar 16 is sensed by pivot angle sensor assembly 118, which contains redundant sensors 101 which may be any sensors known in the art for detecting rotation (e.g., rotation sensors). Hall effect). Other sensors (eg optical or magnetic sensors) can also be used and are therefore within the scope of the present invention.

Any mechanism for providing a force opposing an increasing deflection instruction and restoring the deflection control action to its center position is within the scope of the invention. A preferred embodiment includes constant stress torsion bushing 113.

Torsion sleeve 103 is shown in greater detail in Figure 11. An elastomeric membrane 114 is rigidly coupled to shaft 112 and guard 116 which is fixed relative to platform 12 so that a torsional force of restoration on the axis 112 by virtue of the shear component of the elastic tensioner, which characterizes the membrane when the axis 112 is forced to rotate (around the z axis), concentrically with respect to the protection 116. The restoring torque is symmetric with respect to left / right rotation of shaft 112. The length over which elastomeric membrane 114 is coupled to shaft 112 exceeds the length over which membrane 114 is coupled to shield 116 to maintain a substantially equal shear stress per unit cross-sectional area of ​​the membrane, thereby advantageously increasing the durability and useful life of the membrane 114. Membrane 114 may be uniform in thickness or may be tapered.

Figure 12 is a plan view of a digital level 120 used with a conveyor (eg, conveyor 10 of Figure 7). Considering that the inclination of the conveyor is a control action with respect to the control loop that results in the application of a torque to the wheels 20, it is advantageous that the conveyor is arranged in a substantially vertical position and therefore Therefore, in a situation of zero torque, during the process in which a user rides on the conveyor.

A set of five lights 122 (for example, light-emitting diodes (LEDs)) is preferably arranged in a console 124 arranged in a fixed position with respect to the platform 12 (between wheels 20 arranged transversely), so that it is easily visible by the driver mounted or mounting of the conveyor. In one embodiment, when the colors displayed by the LEDs are all illuminated in a single color (eg, green), this is indicative that the platform 12 is flat and in the correct orientation for mounting thereon. Illumination of an LED in another color (for example, red) indicates a tilt in the direction corresponding to that LED.

The lights on the digital level 120 can also be used to indicate other conveyor situations. For example, a flashing red condition may indicate an alarm condition, such as a fault requiring deceleration and disassembly. In some embodiments, the flashing lights are representative of a situation involving unauthorized use of the conveyor.

According to another embodiment of the invention, separate plates 18 and 19 (shown in Figure 7) are arranged to detect the weight of the left and right foot, respectively. Figures 13A and 13B are illustrations of a platform and plates (eg, platform 12 and plates 18 and 19 of Figure 7). Figure 13A is a plan view of the conveyor platform with the pressure plates removed, showing the placement of the force pressure sensors on the feet, in accordance with an illustrative embodiment of the invention. Figure 13B is a perspective view of the two plates 18 and 19 to detect the placement of the user's left and right feet.

The use of the plates 18 and 19 can be advantageously employed to control or limit the rotation of the conveyor during the assembly or disassembly process of the same in a matter, for example, of comfort and safety. For example, the sensitivity of the control used for conveyor operation (for example, the

ES 2 394 660 T3 conveyor 10 of figure 3) in the direction of the conveyor may be limited in cases where the driver has only one foot on the platform. Table 1 shows steering behavior of a conveyor based on whether one or both of the user's feet are on the conveyor deck (eg, plates 18 and 19 of deck 12 of Figure 7), in accordance with one embodiment. of the invention. Steering behavior is also based on the running speed of the conveyor.

Table 1: Management behavior

<td>User detection</td><td>Speed</td><td>Device response</td>

<td>Left foot only on the conveyor</td><td>Low speed (&lt;3 mph / 1.34 meters / second)</td><td>Limit total deviation movement to the left and sound warning when deviation instruction is ignored</td>

<td>Right foot only on the carrier</td><td>Low speed (&lt;3 mph / 1.34 meters / second)</td><td>Limit total deviation movement to the right and sound warning when deviation instruction is ignored</td>

<td>Left foot only on the conveyor</td><td>Moderate speed (12.5 mph / 1.34 meters / second)</td><td>Maintain control of the deviation but have a speed limit at moderate speed (5 mph / 2.24 meters / second)</td>

<td>Right foot only on the carrier</td><td>Moderate speed (12.5 mph / 1.34 meters / second)</td><td>Maintain control of the deviation but have a speed limit at moderate speed (5 mph / 2.24 meters / second)</td>

<td>Both feet on the conveyor</td><td>All speeds</td><td>Normal functioning</td>

Alternative steering behavior may be specified in alternative embodiments of the invention. For example, alternative conveyor speeds can be specified. In addition, the steering behavior can be changed based on the amount of force applied by the user to one or both of the plates 18 and 19. In some embodiments, the user experience level (similar to the explanation provided) is a factor that is used to specify the steering behavior of the conveyor.

In some embodiments of the invention, the conveyor (eg, conveyor 10 of FIG. 7) is provided with wireless control capability or wireless data telemetry, through, for example, a telemetry unit. Wireless control and wireless data telemetry can be provided unilaterally or bilaterally. In some embodiments, a remote control action device is provided, which can be carried by the user or can be arranged on the conveyor or at a remote location. In one embodiment, the transporter 10 comprises a transceiver that establishes remote wireless communications between the input device and the controller of the transporter 10. The ability to control certain functions wirelessly advantageously enables the manufacture of the conveyor 10 with all the electronic part contained entirely under the platform 12 and more particularly with a control column 16 that does not carry electronic parts.

In various embodiments of the invention, front-to-rear stability can be achieved by providing a control loop (eg, as explained above in Figure 2). The control loop can be used when one or more motors are included for operation of a motorized drive device in relation to contact members on the ground. A pair of ground contacting members may be constituted, for example, by a pair of wheels or a pair of groups of wheels. In the case of wheel groups, each wheel group may comprise a series of wheels. Each of the ground contacting members, however, may alternatively be a series (typically a pair) of axially adjacent arcuate elements, radially supported and rotatably mounted. In these embodiments, the ground contact elements are driven by a motor drive device in the control loop in such a way as to maintain, when the conveyor is not moving, the center of gravity of the conveyor above the contact area of ​​the members in contact with the ground regardless of the disturbances and forces acting on the conveyor. In other embodiments, the ground contact elements are driven by the motor drive device in the control loop to maintain the proper balance for an off-road vehicle.

A ground contact element typically has a "point" (actually a region) of contact or tangency with the surface on which a vehicle (eg, a conveyor) travels or remains. Due to the adaptation of the ground contacting member, the contact "point" is actually an area, in which the contact region can also be indicated as the contact area. For example, the weight of a conveyor is distributed over the contact region, resulting in an arrangement of pressures over the region, with the center of pressure shifted forward during the forward movement. The pressure distribution is a function of both the composition and structure of the wheel, the speed of rotation of the wheel, the torque applied to the wheel and, therefore, the frictional forces acting on the wheel. .

ES 2 394 660 T3

A force in the direction of motion necessary to overcome rolling friction (and other frictional forces, including air resistance). In some embodiments of the invention, gravity can be used to provide a couple of forces around the point of contact with the surface in a direction that has a component in the desired direction of motion. Figure 14 shows the forces acting on a single wheel moving with constant speed v on a flat surface. The principles explained can easily be generalized for operation on an inclined surface and to compensate for any other external forces that may exist. Wheel 140 with radius R_w rotates relative to frame 142 about axis 144 and contacts the surface below at point P. For illustrative purposes only, wheel 140 is assumed to contact the surface at one point.

The wheel is driven relative to the conveyor by a torque T (supplied, for example, by a motor), which in turn creates a reaction torque -T on the conveyor. Since the torque acts around the axis 144, the reaction torque corresponds to a force Fb that acts at the center of gravity (CG) of the system, including the conveyor and the payload, with Fb = T / Rcg being fulfilled, where Rcg is the distance between the axis and the CG of the system. Line 143 from CG to point P forms an angle 0_S relative to vertical 146.

The rolling friction, f, acting on the wheel at point P is proportional to the speed v of the wheel rim, expressing the proportionality f = μν. To keep the speed constant, this force f must be compensated exactly. As a consequence, when providing gravity, the force the condition that must be satisfied is:

<img file="ES2394660T3_D0002.tif" />

(ECN. 4) in which f_b is the component of the reaction force that acts transversely to axis 141 between CG and point P. In order to maintain stability (prevent the conveyor from falling) there must also be a condition of stability, that is, no net force acts on the CG in a direction transverse to line 143. There must be no net torque around the contact point P during motion at constant speed (that is, in an inertial frame of reference in which the point P is fixed. This condition can be expressed as follows:

(ECN. 5) in which F_g sin 0_S is the “tilt” component of gravity and fb is the counter-tilt component of the reaction force on a vehicle (for example, the conveyor) caused by the rotation of the wheel (fb = Fb cosó), where δ is the angle shown between line 143 and line 141.

Equations 4 and 5 can be combined to get F_g sin 0_S eos 0_S = f = μν, so at the limit of small angles (where sin Θ is approximately Θ)

<img file="ES2394660T3_D0003.tif" />

(ECN. 6) showing that for a conveyor increasing speed requires increased incline to overcome the effects of friction. Additionally, a control loop that imposes stability on the system will respond to increased incline by increasing the speed of the system. An additional incline beyond that necessary to overcome the effects of friction results in acceleration, since an additional forward-directed force acts on the CG of the vehicle. Conversely, to achieve acceleration (or deceleration) of the conveyor, additional inclination (forward or backward) must be provided in a manner explained in more detail below.

Figure 15 is a block diagram providing details of the wheel drive interface assembly 153. A panel-shaped peripheral microcomputer 155 receives user control action from a joystick 152 and also from an inclinometer 153. In other embodiments, the inclinometer 153 is another type of tilt sensor (eg, reference sensor of pendulum). The inclinometer 153 provides information signals of angle (Θ) and angle speed (Θ_Γ). To allow controlled tipping in turns by the conveyor, thereby increasing stability while turning, it is also feasible to use a second inclinometer to provide information regarding pitch (Φ) and pitch speed (Φ_Γ). Alternatively, the resultant of system weight and centrifugal force can be used to increase stability during turning. Peripheral microcontroller panel 155 receives input signals from battery stack 151, eg, current battery voltage and battery temperature. The peripheral microcontroller panel 155 also receives other control actions 154 from the driver (for example, signals limited by switches (buttons and pushbuttons) to adjust the platform and to determine the operating mode. The peripheral microcontroller panel 155 is in communication with intermediate of the

ES 2 394 660 T3 bus 159 with a central microcontroller panel (not shown) that can be used to control the wheel motors, as described below in relation to figure 16.

Figure 16 is a block diagram showing suitable control algorithms for use in conjunction with the control assemblies of Figure 15 to provide stability for a conveyor, eg, conveyor 10 of Figure 1, and other vehicles. Other embodiments include a conveyor in which the conveyor and payload are balanced on two ground contact elements, both during travel and in a fixed position. The following conventions are used in connection with the following description:

1. Variables defined in world coordinates and designated using a single subscript in uppercase letters. World coordinates are fixed coordinates with respect to the earth (inertial).

2. An r without a subscript identifies the radius of the wheel.

3. Lowercase subscripts are used to indicate other attributes, for example, right / left, etc .: r = right,

I = left, ref = reference, f = end, s = start.

Four. All the angles are positive in the clockwise direction, in which the positive displacement occurs in the positive x direction.

5. A dot on a variable indicates differentiation in time, for example, θ.

As shown, control algorithm 1660 for left and right wheel motors of a vehicle, for example, wheels 20 and 21 of the conveyor of Figure 1. Control algorithm 1660 has actions of control of linear speed of the left wheel with respect to the world coordinate system, Θ, réwi, and linear speed of the right wheel, r 9_Wr · The control algorithm 1660 also has control actions or directional inputs 1600 that are determined by a joystick arranged along the X and Y axes of a reference coordinate system. The control actions Θ, Θ, and error signals x and X (described below), are respectively subjected to the gains K1, K2, K3 and K4 and become control actions for the summing device 1619. The adder 1619 produces the basic offset torque instruction for the left and right wheels, as previously described in connection with Figure 2. The output of the adder 1619 is combined with the output of the offset PID loop. 1616 (described below) at adder 1620. The output from adder 1620 is divided at divider 1622. The output of the summing device 1620 is limited in the saturation limiter 1624, producing a torque instruction for the left hand wheel. Similarly, the output of the summing device 1619 is combined with the output of the PID loop 1616 in the summing device 1621. The output of the summing device 1621 is divided in the divider 1623. The output of the divider 1623 is limited in the saturation limiter 1625, producing a torque instruction for the right wheel.

The 1660 control algorithm recognizes that a directional instruction along the X axis shifts the reference coordinate system, as shown in Figure 1 along its X axis with respect to the world coordinate system (representing travel surface) at a speed proportional to the travel of a joystick. A directional control action along the Y axis rotates the reference coordinate system, as shown in Figure 1, about its Z axis at an angular velocity proportional to the movement of the joystick. Movement of the control lever in the positive X direction is here interpreted to mean forward movement. Movement of the joystick in the negative X direction means reverse movement. Similarly, moving the joystick in the positive Y direction means turning to the left, counter-clockwise viewed from above. Joystick movement in the negative Y direction means right turn, clockwise viewed from above. Therefore, the Y and X directional control actions receive "deadband" through the freeband blocks 1601 and 1602, respectively, to extend the neutral position of the control rod. Outputs 1602 and 1602 are subjected to gains K11 and K10, respectively. The outputs of gains K10 and K11 are inputs to speed limiters 1603 and 1604, respectively. Speed ​​limiters 1603 and 1604 limit the angular and linear accelerations, respectively, of the reference coordinate system. The speed-limited outputs of the speed limiters 1603 and 1604 are inputs to the summing device 1605. The output of the summing device 1605 is the reference speed K_rref and the output of the summing device 1606 is the reference speed X /_rer x_{r re}f and X / ref are subtracted in summing devices 1608 and 1607 from the linear velocity compensated input signals r®_w¡Yr®_wr for left and right wheels to get X / yx speed error signals_r for the left and right wheels within the reference coordinate system. The average of the speed error signals X / yx_r determined by summing device 1617 and divider 1618 produces a linear velocity error signal. The offset error signal x is derived by integrating X / yx_r in integrators 1610 and 1609. The outputs of integrators 1610 and 1609 are inputs for saturation limiters 1611 and 1612. The outputs of saturation limiters 1612 and 1611 are averaged by summing device 1613 and divider 1615. The difference of these displacements, determined with the summing device 1614, produces the deviation error signal ψ.

ES 2 394 660 T3

The deviation error signal ψ is input into a standard proportional-plus-integral-plus-derivative (PID) control loop 1616. The output of the PID control loop 1616 is combined with the output of the basic offset torque instruction from the summing device 1619 to produce individual torque instructions at the wheels. The individual wheel torque instruction causes the wheels to maintain back-to-front stability and also causes the conveyor to align with the axes of the reference coordinate system and follow the origin of the same according to directional control action instructions 1600.

In another embodiment of the invention, speed limiting is used to maintain balance and control, which could otherwise be lost if ground contact elements (eg wheels) could reach a maximum operating speed of the conveyor. The term "maximum operating speed" as used in this description, refers to the maximum speed at which the vehicle (eg the conveyor) is momentarily capable of being propelled. This maximum operating speed is typically a function of an instantaneous capacity of the conveyor. For example, the maximum operating speed may be a function of the capacity of the drive system and / or the capacity of the energy storage device arranged to drive the drive system. An energy storage device can be a battery. The instantaneous capacity of the energy storage device is a measure of the instantaneous power that can be supplied by the device. The "maximum capacity" of the energy storage device is a measure of the maximum power that the device can supply at any one time. The terms "intervention speed band", "intervention speed" and "speed limit" used in this description refer to a range or band of speeds ranging from a "intervention speed" at the lower end to a "speed limit" at a higher end. Intervention speed is a speed threshold at which means can be used to reduce the speed of the conveyor. A conveyor will typically be used with a margin between the maximum operating speed and the speed limit, as shown in Figure 17. This margin helps to ensure that the conveyor maintains equilibrium over a range of operating conditions.

The speed reduction can be achieved by tilting the conveyor again in the opposite direction with respect to the current direction of travel, which causes the conveyor to slow down. (As explained above, the extent and direction of the tilt of the system determines the acceleration of the conveyor). In this embodiment, the conveyor is tilted back, adding a tilt modification to the tilt value of the inclinometer. The speed reduction can take place whenever the speed of the conveyor exceeds the intervention speed. The angle modification is determined by consulting the difference between the conveyor speed and the integrated intervention speed over time. The automatic tilt modification sequence can be maintained until the conveyor slows down to the desired lowering speed (one speed below the intervention speed) and the tilt angle can be smoothly returned to its original value.

An electric motor connected to a wheel that supports a payload exerts a certain effort to maintain a stable speed. For a stationary vehicle located on a slope, the electrical power source supplies the effort through the motor. When the apparatus begins to move down the slope, the speed increases as the potential energy is converted into kinetic energy. Once the steady state speed has been reached, the potential energy is no longer converted to kinetic energy and there is no increase in speed. Instead, the potential energy can be converted into electrical energy through the motor. The potential energy is converted into electrical energy, minus the losses of the system. Electric power, for example, can charge a battery used to drive the engine.

The motor current is proportional to the combined weight of the vehicle and the supported payload and the slope of the surface below. Together, these two parameters determine the amount of work gravity can do on the system. If the surface slope is zero, gravity doesn't work. Figure 18A shows a wheel 180 traveling on a zero slope surface. A forward torque TF must be applied to wheel 180 for it to move in the forward direction V. The force of gravity Fg does not contribute to the amount of work required to propel wheel 180 forward with a body sloping surface. nor does it diminish it. Figure 18B shows a wheel 180 traveling down an inclined surface (slope α). The force of gravity Fg thus contributes the amount of work required to propel the wheel forward V. Since the wheel 180 is traveling downward from the sloping surface, it must be applied to keep the wheel 180 moving at speed. constant, an inverse torque Tr proportional to the force of gravity (Fg), applying the desired constant speed. In other embodiments, the wheel 180 can travel up a slope. Other forces (eg frictional forces) contribute to the magnitude of the torque T required to propel the wheel forward, as explained above with respect to Figure 14. For the sake of simplicity, they have been ignored in the above discussion. . For a given surface slope, the greater the vehicle weight and payload, the more work gravity can do on the system in creating more current when accelerating or decelerating. The amount of current generated when accelerating or decelerating is reduced by rotational losses so that for small slopes or reduced payloads there may be no motor action or regeneration.

ES 2 394 660 T3

A given drive system is typically limited in the amount of electrical current that can be handled. Considerations such as motor drive assembly hardware, battery capacity, and thermal limitations affect this limit.

Figure 19 shows a block diagram of a power module 1900 of one embodiment of the present invention. A trim controller 1910 generates an instruction signal provided to the motor amplifier 1920. The motor amplifier 1920 applies the appropriate power to the motor 1930 based on the instruction signal. The trim controller 1910 receives control actions from the user and system sensors and applies a control law, as described in detail below, to balance and govern the movement of the conveyor, in accordance with the instructions of the conveyor. Username. The motor 1930 rotates a shaft 1932 supplying a torque T at an angular speed ω to one or more wheels (for example wheels 20 and 21 shown in Figure 1), which are coupled to the shaft 1932. In one embodiment of the present invention, the motor 1930 is a three coil brushless DC motor. In this embodiment, the 1930 motor has three sets of stator coils, although any number of coils can be used. The stator coils are electrically connected to a power stage 1924 by coil leads 1937 capable of conducting large amounts of current or high voltages.

The motor amplifier 1920 contains an amplifier controller 1922 and a power amplifier stage 1924. The amplifier control 1922 may be configured to control the current or voltage applied to the motor 1930. These control modes may be referred to as the drive mode. current control and voltage control mode respectively. Power stage 1924 switches power source 1940 on or off for each coil, based on the switching of power stage 1924. Power stage 1924 is controlled by amplifier controller 1922. An inner loop 1826 detects whether the output of the power stage 1924 equals the computing value and feeds back an error signal to the amplifier controller 1922 with a closed loop bandwidth, preferably on the order of 500 Hz. The amplifier controller modifies the output of the power stage 1824 based on the error signal. Additionally, control by the amplifier controller 1922 is based, in part, on a feedback signal from the shaft feedback sensor (SFS) 1935.

The feedback sensor 1935 is coupled to a trim controller 1910. The feedback sensor 1935 provides information regarding the axis position or movement to the trim controller 1910. The axle feedback sensor 1935 can be any sensor known in the art. capable of detecting the angular position or speed of a rotary axis and includes tachometers, "encoders" and "resolvers". In order to obtain a measurement of the shaft rotation speed from a position signal provided by the shaft feedback sensor 1935, the position signal is differentiated by the differentiator 1908. The external feedback loop 1942 operates over a width of The characteristic band of the trim control provided by the trim controller 1910 and can be low, on the order of 20-30 Hz.

While current and voltage control may be equivalent in certain applications, voltage control is advantageously applied in conveyor control embodiments in which the bandwidth of the outer loop is more than 3-4 times slower than the bandwidth. internal bandwidth of the closed loop. Figure 20 shows a 2010 electric model of a motor. The motor has a pair of terminals 2011, 2012 across which a voltage V is applied. The motor 2010 also has a rotation axis characterized by an axis speed ω and a torque T. The motor 2010 can be modeled by the rheostat 1930 of the set of resistance R that carries a current i in series with an ideal motor 1935 that has a voltage drop V_emf For an ideal engine:

Vemf ^— k_vCú (ECN. 7)

T = kc * 1 (ECN. 8) where k_v and kc are motor constants. The 2030 series resistor models the motor losses.

In another embodiment of the invention, a method for estimating the instantaneous capacity of a battery is provided. As shown in Figure 1, a simplified model 2100 is used for the battery consisting of a "perfect" DC voltage from source 2110 with a voltage V_oc in "open circuit", a series resistance for the battery R_bat a stream l_bat and a battery voltage V_bat, V_oc and R_bat cannot be measured, but can be estimated from measurements of V_bat the_bat. Ideally, these variables should follow a linear relationship:

Vbat V_oc - (lbat * Rbat) (ECN. 9)

Since this linear realization is ideal, the measured values ​​of V_bat the_bat they will probably present a "scatter plot." It should be noted that "statistical", as used in this description, refers to the design of deductions as to the value of a parameter based on sampling of the value per measurement or intervals that can be regular or irregular with respect to the distribution of samples in time or in terms of another

ES 2 394 660 T3 dimension. The verb "filter" as used in this description refers to the process of extracting a value attributable to a single point in time from a series of data that can be obtained in successive samples and can be subject to random or systematic fluctuations. or both. The application of filtering techniques, as known in the art, to the data allows estimated values ​​of V_oc and Rbat- For example, a regression analysis, using the least squares technique can be used to deduce estimated values ​​of V_oc and Rbat from the measured values ​​Vbat and Ibat-Voc and Rbat will change, for example, due to ambient temperature, battery temperature, battery age, battery utilization (both general utilization and utilization pattern ) and over time when the battery charge runs out (and / or is regenerated). Accordingly, a more accurate estimate can be obtained if the most recently measured values ​​of Vbat and Ibat are used for the regression or more recent values ​​are weighted more attenuated than the previous values.

In another specific embodiment of the invention, as shown in FIG. 22 (step 2200), re-measured values ​​of Vbat and Ibat are used to correct for the estimated values ​​of Vbat and Ibat using a low-pass filtering algorithm. The variables are initialized (step 2210), setting V_oc and Rbat in typical values. Vbat and Ibat are measured periodically (step 2220). To ensure that the signal is sufficiently “rich” (that is, there is a statistically significant deference between the data points), the squared distance, D, of Vbat and Ibat from the last accepted values ​​of these variables V_prevel_prev is computed (step 2230).

Distance from previously accepted measurements identifies data points that can provide additional information from which to fine-tune the estimation of current battery parameters. For example, when the conveyor is idle, little current is drawn and a series of such measurements could skew the estimated value for the battery parameters from their actual values ​​as filtering proceeds. An appropriately set threshold for D can be used to mitigate the impact of these data points on the estimate.

The following calculations can then be carried out:

(1) calculate update gains K_voc and K_rbat (step 2240):

<td>'κ_νο;</td><td></td><td>Pa</td><td>Pb '</td><td> 1</td><td></td><td>Pa</td><td>-Pb ^ ba, '</td>

<td>J7_bal.</td><td></td><td>.Pb</td><td>Pc_</td><td>1--------------- 1 O i____________</td><td></td><td>-Pb</td><td>~ Ρα * 7α, _</td>

in which p_to is the element of the direct covariance matrix V_oc, Pb is the cross-coupled covariance matrix element and p_c is element of direct covariance matrix Rbat, (Note: p_to, Pb and Pe represent the uncertainty in the state estimate);

(2) calculate the error between the battery health estimate and the new data point (step 2250):

Err = Vbat - (V ocIbat * Rbat) (ECN. 11) (3) update battery health estimate (step 2270):

(if D is less than the threshold (step 2260), K_rbat is set to zero (step 2265), so Rbat is not updated)

Voc = v_oc + Kvoc * Err (ECN. 12)

Rbat Rbat + K_rbat * ElT (ECN. 13) (4) update variables of the signal content (step 2280), if D is greater than the threshold (step 2275)

V prev V bat (ECN. 14)

<img file="ES2394660T3_D0004.tif" />

(ECN. 15)

The process can continue with repeated measurement of V_bat θ Ibat (step 2220), thus continuously updating the estimates of Vbat the_bAt In another embodiment of the invention, estimated values ​​of battery parameters are used to calculate maximum operating speed for a conveyor based on battery condition and other conveyor parameters, such as motor current. For example, the maximum operating speed of conveyor Y can be modeled by a linear equation of the form:

ES 2 394 660 T3

Y - Μ * Imax + B (ECN. 16)

The values ​​for M and B can vary over time and either Μ or B can be a function of current values ​​of the carrier, depending on operating parameters, such as battery open circuit voltage and internal resistance such as parameters such as return EMF gain and motor resistance.

Actuator systems have a physical limit on the amount of torque they can supply and the amount of electrical current that can be found in the system. Output torque and current magnitudes in the drive system are interrelated. Torque is a function of current (and vice versa), as shown in the ECN. 8 in relation to Figures 19 and 20. In voltage control mode, adjusting the magnitude of the torque adjusts the overall current in the drive system. Similarly, a current limit limits the amount of torque that can be generated by the drive system. In this way, if an actuator has a maximum torque, the current capacity also has a maximum. The physical limit on the total amount of electrical current in the drive system applies to all forms of current (eg, ambient temperature, battery age, current generated by acceleration or deceleration). Any current that passes through the vehicle's drive device uses a certain part of the total drive capacity and contributes to the overall current limit. For example, regeneration current (current generated by applying torque in the opposite direction from the direction of travel) reduces the amount of current available for braking. This is the reason for both the regeneration current and the braking current being negative and increases the overall current limit. Typically, the drive system can control the amount of current (that is, amount of torque that can be applied in response to available current) that constitutes the capacity used for acceleration or deceleration and then estimates the remaining control capacity of the drive. stream. By estimating the remaining controllability of the current, the system can limit the behavior of the vehicle or provide additional braking force by some other means.

A dynamically stabilized conveyor, such as the one described above, can operate in a way that maintains a margin for its actuator device in order to control various motorization transients that may occur (for example, the need to accelerate the wheels over small obstacles). That is, for some operating conditions, the wheels need to accelerate to stay below the center of gravity in order to balance the vehicle. Similarly, there may be an operational limitation requiring a certain actuator margin that must be maintained in order to bring the vehicle to a safe stop if the integrity of the system fails. When driving up a slope or on a flat surface, the vehicle stalls as the wheels accelerate ahead of the center of gravity, causing the system to lean backwards. Leaning back causes a reduction in torque, thereby reducing speed.

The behavior of the conveyor is limited and its speed is reduced by the modulation of the angle of the conveyor. This reduction in performance can be related to the overall current. That is, the greater the vehicle weight and payload and the greater the slope, the greater the amount of current created. For example, additional current may be required on an uphill ride due to the increased torque required to tilt the vehicle back again before stopping. Alternatively, additional current can be created when traveling downward due to regeneration current created in braking. The additional current contributes to the overall current that can cause the global current limit (i.e., the physical current limit) to be reached, resulting in the reduction of the speed limit. A lower speed limit decreases the amount of possible sustained deceleration. A lower speed limit reduces the magnitude of the possible sustained deceleration. Lowering the speed limit does not increase the braking capacity, but rather puts the system in an operating situation, in which the need to use the braking capacity is less likely, and in which the braking capacity is used during a shorter time from a higher initial speed. Since the conveyor uses the electric motor to generate braking forces, the very act of slowing down also regenerates current.

There are various methods for measuring vehicle speed and acceleration, which can be used in embodiments of the invention. For example, rotary encoders can be used to measure the speed of one or more wheels on the vehicle. The derivative of vehicle speed versus time can be used to determine vehicle acceleration. In addition, accelerometers can be used to determine vehicle speed.

Figure 23 shows the relationship between measured motor current and speed limit for an illustrative embodiment of the motor. When the measured motor current is greater than or equal to -2 (A), the vehicle speed is set at 5.558 (m / s). When the measured motor current is less than or equal to -20 (A), the vehicle speed is set to 1.178 (m / s). When the measured motor current is between -2 (A) and -20 (A), the speed is limited along a straight line between -2 (A) and -20 (A). The values ​​of these limits (current values ​​and / or speed limits) can vary, depending, for example, on the level of experience of a certain user.

ES 2 394 660 T3

In some embodiments, the overall current limit is based on operating characteristics of the conveyor when traveling uphill. In some embodiments, the overall current limit is based on the operating characteristics of the conveyor traveling downward. In some embodiments, a measured motor current limit must be reached for speed limiting to begin (eg, 2 (A), as shown in FIG. 23).

In vehicles that do not incorporate the principles of the present invention, positive feedback occurs during acceleration or deceleration causing an erroneous decrease in conveyor speed. Positive feedback causes unnecessary additional deceleration, because speed is further limited in response to current exceeding its threshold value. The lower speed limit requires acceleration when traveling uphill and deceleration when traveling downhill. Acceleration or deceleration causes another increase in current, since a torque even greater than the torque that was initially caused by the initial exceeding of the threshold current must be applied to further accelerate or decelerate the vehicle. The current limit is then further exceeded because the larger torque represents larger current generation. This global cycle of increase-deceleration current (in addition to eventually causing an undesirable complete stop) also reduces the behavioral margins available to respond to transients and faults. In vehicles incorporating principles of the present invention, the additional current from acceleration or deceleration is taken into account so that it is not considered as additional current due to slope and payload. To minimize the effect of current associated with the slope and weight of the vehicle and payload and to avoid unnecessary speed limitation and improve the dynamics of transients, the control algorithm separates the actuator current necessary to go up or down by a slope with respect to the current required for acceleration or deceleration. An estimate of the magnitude of current measured due to acceleration or deceleration can be removed from the total current measured. Eliminating the magnitude of current due to acceleration or deceleration allows speed limit adjustment based on current resulting only from grade and payload, which was the original purpose.

Fig. 24 is a schematic view showing the speed limitation of a conveyor controller in accordance with an embodiment of the present invention. A torque module 2402 determines the average steady-state torque and torque during acceleration or deceleration of the vehicle traveling on the surface below. Average steady state torque and torque during acceleration or deceleration are provided to a speed module 2401. Speed ​​module 2401 also receives control action signals representing total measured current (ltot), total vehicle system weight and payload (e.g. driver or load), vehicle torque, vehicle acceleration, and vehicle speed. vehicle. In this embodiment, the output of the speed module 2401 is the desired lean angle because the lean angle controls the speed of the conveyor. The desired tilt angle is supplied to a tilt controller 2303, which controls the angle of the conveyor.

The speed of some vehicles is not controlled by controlling the angle of the vehicle. In these vehicles, a speed controller is used to control the speed of a vehicle by varying, for example, an accelerator command signal applied to the vehicle's accelerator instead of varying the commanded lean angle applied to the vehicle's engine.

Fig. 25 is a flow chart showing the speed limiting operation of a conveyor controller when traveling downhill according to an embodiment downhill, in accordance with an embodiment of the present invention. Torque module 2402 of FIG. 24 detects and determines the slope of the underlying surface on which the vehicle is traveling, step 2501. When the vehicle is traveling downward, in step 2502, regeneration current (Ireg) is created and measured, step 2503. If the regeneration current increases (step 2504, then the maximum permissible speed limit of the vehicle decreases (step 2505) based on compensation of the regeneration current signal for vehicle acceleration, as explained above. An acceleration-compensated average current signal is produced (step 2506) causing the conveyor angle modulation (step 2507) by the incline controller 2503. The angle controller 2503 controls the angle of the conveyor based on the weight transfer to the wheels (step 2508).

In effect, the acceleration compensated average current is an estimate of the combined effects of slope and payload. In the embodiment of the invention implemented on a dynamically stabilized conveyor, a generalized estimate (for example, a fixed gain in the vehicle control system) of the vehicle mass can be used and the payload can be used in the determination of the average acceleration compensation current. For example, in one embodiment the estimate is that 5 amps are required to decelerate the vehicle by one meter per second. In other embodiments, the total weight of the system is measured or estimated.

Principles of the present invention can be used in a number of other types of vehicles. In some embodiments of the invention, the principles of the present invention are used with statically stable vehicles.

ES 2 394 660 T3 (eg cars, off-road vehicles). For example, in one embodiment of the invention, the principles of the present invention are applied to a statically stable four-wheeled automobile. The automobile includes two or more electric motors coupled to wheels of the automobile. Electric motors are used as the primary means of acceleration and deceleration of the automobile. Referring to Figures 24 and 25, instead of using the angle of the car to control the speed of the car, a separate controller and / or actuator is used to control the speed of the vehicle based on, for example, the average current signal. compensated in acceleration. For example, the acceleration compensated average current signal can be provided to an actuator that controls the throttle of the automobile engine, thereby controlling the speed of the automobile. Alternative apparatus and methods for controlling the speed of a vehicle are within the scope of this invention.

In one embodiment, the acceleration compensated average current depends on the total weight of the system. The total weight of the system can be accurately reflected by measuring or estimating the weight transferred to the wheels.

In one embodiment, the slope of the surface and the weight of the payload can be estimated based on measurements of torque, acceleration, and speed. Grade and payload estimates, based on measurements of torque, acceleration and speed, can also be applied in a general way to controlling and limiting vehicle performance with respect to hill climb performance limits.

In some embodiments, the maximum allowable limiting speed (eg, in step 2505 of FIG. 25), increases as the regeneration current decreases. When the regeneration current decreases, the overall capacity of the actuator increases, allowing a greater capacity of the actuator for braking. This results in an increase in the maximum permissible limit speed. In some embodiments, the refresh current limit may be higher based on user experience. A more experienced user is likely to know how to drive the vehicle in a way that minimizes the need to brake or slow it down during certain maneuvers. For example, the user may know the proper body positioning for quick turns or appropriate speeds to go through different terrain. This experience can allow the arrangement of the drive system at a higher current limit because a lower capacity of the drive device is needed for braking and transients. Thus, embodiments of the invention provide smooth control of the speed of the electric vehicle when descending a slope, even if the speed limit decreases during the descent. Additionally, increased speed and torque margins are preserved to respond to transients or system failures.

The described embodiments of the invention are intended merely by example, and numerous variations and modifications will be apparent to those skilled in the art. In particular, many of the controllers and steering and speed control methods that have been advantageously described can be applied to electric vehicles that are not compensated personal transporters. Balanced conveyors have specific requirements to control the vehicle, as explained in the foregoing description and in US Patent No. 6,789,640. All such variations and modifications are intended to be within the scope of the present invention, as defined in the appended claims.