Control system having variably biased manipulatable unit

(24) Race day (62) National application number (86) International filing day (86) Filing date for European patent application (30) Priority information (11) Publication cenngs86-02-03 number 442 852

84-10-19

83-04-18

83-04-18

The application has been submitted as a Swedish patent application

Π Completed international patent application with number

NOT converted European patent application with number (71) Applicant SAAB-SCANIA AB, 581 88 Linköping SE (72) Inventor K L. Nordström, Linköping (74) Representative Rustner L (54) Designation procedure and arrangement for control systems to achieve elevation torque gradient for small actuator movements (56) Published publications: - (57) Abstract:

In a control system with a manual actuator (1) by means of which a controlled means (29) is provided, the actuator position (cf) and change of actuator position are determined. A torque motor (5) is coupled to the actuator to apply an actuating torque (F) to the display. Based on the information on exhibition location (cf) and the change in exhibition position, momentBt (F) is determined depending on a first and a second characteristic, y?) For increasing and decreasing exhibition position (tf). When a turning point for the actuator's display occurs, corresponding to a change of display position from increasing to decreasing display position or vice versa, the torque (F) is determined depending on a third characteristic (y ^), goes through the turning point and has a

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TL

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The present invention relates to a method and apparatus for providing, in a control system with a manually adjustable actuator, which serves to actuate a controlled member and applied by a force generating unit, preferably a torque, counteracting actuator's display, to an increased torque gradient. for small maneuvers, wherein the actuator's display position or a quantity dependent on it is utilized to regulate the power generating unit in accordance with predetermined criteria.

In the case of vehicle control systems, especially when controlling the aircraft's rudder, it is advisable that the joystick or corresponding actuator is affected by an exhibit counteracting moment. The moment strives to return the actuator to its neutral position and at the same time provides the driver with additional information about the steering action he produces.

Conventionally, this is accomplished by imposing a lever increasing with the display position, which usually results in a linearly increasing lever force, which must thus be overcome by the pilot upon continued display of the lever. This results in lasting aircraft maneuvers

8302137-8 lever force, which, for larger lever joints, requires a relatively high muscle load. This has a negative effect on the fine control required around different work points, corresponding to different lever rake and load factors. It is desirable to reduce the total durable lever power while maintaining a high informational lever power gradient to facilitate fine-tuning.

With a conventional, manually controllable trim function, it is possible to achieve a reduction in the lever force in case of large lever movements and load factors. However, such a trim feature has disadvantages which are not acceptable for high performance aircraft. The trim function is switched on by operating a separate switch, which makes handling difficult. In addition, time is needed to adjust the trim function. The trim function also interferes with fine-tuning. Another disadvantage is that when the joystick is unloaded, you do not return to the same flight condition as before the trimming.

These inconveniences are particularly troublesome for control systems in modern fighter aircraft, where fast and reliable responses and control commands are required from the pilot. However, similar disadvantages also exist in control systems in completely different applications.

The object of the invention is to provide a solution for the above problems, which provides partly a low, actuator or lever display counteracting torque with a correspondingly low gradient, resulting in a low lever power, and a high informational torque gradient, resulting in a higher and fast growing lever power.

This object is achieved by a method and a device of the kind mentioned in the introduction, which are characterized by the features set out in the following claims.

The invention is described in more detail below with reference to the accompanying drawing, in which Figure 1 shows schematically a control system for an aircraft tipping channel, Figure 2 shows a principle torque diagram according to the invention, Figure 3 shows a torque diagram according to the invention particularly suitable for the tipping channel of an aircraft control system, and Figure 4 is a flowchart of an algorithm for realizing the torque diagram of Figure 2 or 3.

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The invention can be applied to a variety of control systems in which a controlled device is provided by means of an operator-controlled control device. In order to constitute a limitation of the invention, in the following an application to aircraft is described and more particularly to the tipping channel. Other suitable applications are manipulators of various kinds.

In order to simplify the following production, continuous torque and torque gradient are used to denote the force effect which opposes the actuator's display. The terms used should therefore include any equivalent form of counteracting force or gradient.

Figure 1 shows a simplified control system for the tipping channel in an aircraft. An actuator in the form of a joystick 1 is pivotally supported around an axis XX to be exhibited from a neutral position RR by a pilot in either of two directions of rotation. To the lever 1 is connected a signal transducer 2 which produces a signal corresponding to the lever position 8 of the lever. As indicated in the figure, the signals are indicated to be positive for lever movements on one side of the net position and negative on the opposite side. The transducer 2 is signal-related to a computing unit 3 which is adapted to provide, at predetermined criteria, such as flight conditions and load factors, a signal output which, after appropriate gain in an amplifier 4, is applied to an execution means 6 in the form of a servo unit. , which equips a guided member in the form of a rudder surface 29 to an angle -B.

The generation of this rudder signal may conveniently be effected by the method and apparatus for providing reduced equipment gradient for small operating movements which is described in more detail in a simultaneously filed patent application.

The computing unit 3 is arranged in accordance with the present invention to determine and provide, according to its applicable criteria, a signal Fjq, which, after suitable amplification in an amplifier 28, generates a power generating unit 5 coupled to the control lever 1 to produce a display against the control lever. working moment. The signal F F thus corresponds to the magnitude of the artificial torque imposed on the lever and gives rise to a lever force which must be overcome by the pilot during the control of the aircraft.

The power generating unit 5 is preferably a torque motor directly acting on the shaft 30 of the control lever, as schematically shown in Figure 1.

The invention is particularly suitable for control systems with a digitally operating computing unit in the form of a computer 3, which is programmed to execute the algorithms required for different control cases. However, the invention in control systems that have low speed requirements can also be implemented with discrete components to perform the required algorithms analogously or digitally, although this is less closely related to today's technology.

According to the invention, the display position of the control lever 1 is sensed and at the same time, the changes made in the display position of the lever are determined continuously. In this way, a change in the direction of movement of the lever can also be detected. This is done by evaluating the signal from the signal transducer 2 to the computer 3 in the computer.

The computer program includes an algorithm which, depending on the display position of the control lever and and any change in it, determines the torque that the torque motor 5 will generate. The computer thereby determines the said torque representing the signal F The procedure is illustrated in Figure 1 by means of a block 9. Thus, the signal obtained at the output of the computer which constitutes a set point delivered to the amplifier 28 represents independently of any further computer processing the torque of the torque motor.

In Figure 1, the computational unit 3 is shown as a computer in an overview block diagram. The computer, which can be given a suitable embodiment for the application in question, comprises in principle a central unit 31, a program memory 32 and a primary memory 33 in cooperation. At the input and output of the computer are connected interface units 34 and 35 respectively, which adapt the input signal to the computer and the output signals determined by the computer to subsequent units. The algorithm used to determine the torque in block 9 is stored in program memory 32 where there may also be other algorithms illustrated by blocks 7 and 8. The latter's effect on signal processing is not described when it is not required for the understanding of the present invention.

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In a torque diagram in Figure 2, for positive display positions of the control lever 1, it is shown how according to the invention a torque representing signal F F is determined for different input signals cTjq, corresponding to the current display position of the control lever 1. In a first interval (starting from the neutral point 0) of the control system (0-i for the input signal, a torque signal value is determined by a characteristic y ^, which in a known manner has a suitable high torque gradient y ^, to facilitate trimming of the flight condition around the neutral point. describes, for each, the actuator position display position representing the input signal / in the interval the relationship between the torque signal and the lever actuator position. The characteristic can be curvilinear and then has a torque gradient that varies over the interval.

In a second adjacent interval of the signal, for increasing control lever display, the torque signal f- is determined according to a first characteristic y ^ with a first torque gradient y ^, and for decreasing display position the torque signal is determined according to a second characteristic y₂ which has a second morning gradient y ^ · Characteristic y₂ differs from the characteristic in that it represents one and the same input response to an arbitrary display position /, represents a smaller step than the characteristic. The first and second characteristics are monotonically increasing to ensure unambiguity between the actuator's display and the torque signal. The characteristics and y₂ are thus lateral and delimit a belt-shaped torque signal area ELHGE. As shown in Figure 2, the characteristics and y are₂ torque gradients and y₂ less than the fourth characteristic y are less steep than this one.

An operation of the torque motor 5 according to either of these two characteristics y 1 and y₂ occurs when monotonically changing the display of the control lever 1, e.g. in the case of rough control, whereby the control lever is subject to relatively large changes in the display position. When after rough adjustment of the control lever at e.g. increasing exhibit position to an arbitrary torque point on the characteristic y_z thus, this torque point of the actuator's display constitutes a turning point to decreasing display position, the torque signal Fyq is determined, depending on a third through the turning point, characteristic y med with a third torque gradient γ, which is of the same order of magnitude of the fourth characteristic and thus substantial is slightly larger than the torque gradients of the first and second characteristics, respectively y₂Mathematically, this third characteristic y can be said to belong to a number of extremely closely related characteristics y ^, all of which intersect the first and second characteristics respectively y₂ and has essentially the same shape in the belt-shaped torque signal region ELHGE. Each such third characteristic is generated as a result of a turning point occurring in the lever display along any of the characteristics and₂· Thus, in the example in the figure, a third characteristic is obtained starting with the turning point. The amount of third characteristic also contains a lower end boundary characteristic EL of a torque signal region ELHGE which connects to the fourth characteristic y Sam can be seen in Figure 2, the amount can also contain an upper boundary characteristic GH.

When the control lever from the turning point is exhibited to new points, for example, Tj in Fig. 2 in accordance with the currently applicable third characteristic, the determination of the torque proceeds in dependence of this characteristic as long as the position of the control lever or the developed torque point is within the torque signal range El HG. In case of continued small lever corrections in both directions between the control lever's exhibit positions corresponding to the torque points and T₂ thus, for the control of the lever force, the high torque gradient, which characterizes this third characteristic and the other associated said amount, is maintained for the third characteristic. From this it appears that the control system at the control lever's display in the area ELHGE will. work with a too small lever correction for a larger gradient or gain, which especially in the case where this larger torque gradient occurs in parallel with a lower equipment gradient (according to the above-mentioned, simultaneously filed patent application) significantly facilitates the driver to make and manually detect accurate rudder settings. Said area can therefore be referred to as fine control area.

If the driver, under fine control in the area of ​​ELHGE, performs a lever movement, e.g.

towards increasing exhibition position,?, which means that the point '- characteristic y ^ is reached, in the case of continued lever movement the same direction of torque points will instead be determined according to this characteristic.

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The same operation applies when operating according to the characteristic y₂ when the driver resets the control lever 1 so that the display angle S decreases. In this case, the second characteristic y applies₂ as long as the changeover is monotonous. On the other hand, if such a maneuver is at an arbitrary point T₂ on the second characteristic y₂ performs a lever correction to an increased value at the display angle6 so that the direction of movement is reversed at point T₂, applies by analogy to the foregoing that each torque point, e.g. T ^, is defined by the third characteristic y y.

In general, if the control lever's display for fine-tuning / fine-tuning is changed so much that a torque point determined according to the third characteristic y should fall outside the fine-tuning area ELHGE, the torque value will again be determined by adjacent first and second characteristics, applicable as before for increasing reep, declining exhibition positions. It thus becomes the driver's way of handling the control lever that decides whether or not the control system will work with a finely regulated lever power.

In the diagram in Figure 2, a fifth characteristic γ visas is shown in an interval S 6> 6 kan, which may have a different torque gradient adapted for such maneuvering operations which should not normally occur but which an airplane in an emergency may need to perform, e.g. to avoid collision.

In the torque diagram of Figure 2, all characteristics have a general curvilinear shape. In many applications it is no disadvantage to utilize characteristics with simpler, rectilinear form. This also applies to the application of a control system for an aircraft tipping channel. It should be mentioned here that for the role channel in such control systems similar torque gradient functions are not considered relevant because fine control normally takes place around the neutral position, but here a clear control function passing through the neutral position can best be considered to meet the need.

Figure 3 shows a diagram with rectilinear torque characteristics, which is advantageously applied to the tipping channel in an aircraft control system. The diagram occupies, on the one hand, a fine control area E'L'H'G'E 'corresponding to that provided in FIG. 2, and a second belt-shaped area A'B'D'C'A¹ applicable to negative lever positions, which in a conventional manner may be limited to a smaller angular range than the positive one. The diagram is otherwise equivalent on both sides of the zero point 0, so the following statement is limited to the positive area. In the same way as in Figure 2, the fine control area E'L'G'H'E 'is delimited by a first and a second torque characteristic y'_q and

8302137-8> '2 These are here rectilinear and parallel. Thus, they have the same constant moment gradient k The characteristics y ', which, by analogy with the foregoing, constitute an amount in which each individual characteristic is generated depending on where on the first or second characteristic a turning point of the control lever ^ e.g. respectively. T?, Will occur, are also rectilinear and thus have a constant torque gradient, here referred to as k. The fourth characteristic y ', passing through the rieutral point 0, is here the continuation of the lower grating characteristic ΕΊ. in the set of third characteristics y 'and thus has the same torque gradient k k. In a range of the input signal, corresponding to extreme display values, there is a fifth rectilinear characteristic y $, which is shown here with the same torque gradient k k, as the set of third characteristics.

A method based on rectilinear torque characteristics of this type has been successfully tested by test aviators, whereby an increase in the torque gradient to approximately the double value for the third characteristics in a fine control range of 2 degrees was used. The tests showed an advantageous impact on steering performance and steering activity and an improved lever force feel during the operation.

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Figure 4 shows a flowchart of an algorithm for realizing the torque diagram shown in Figure 3. Three condition blocks 10-12 are first determined, at which interval the input signal is located. If the input signal falls within either of the intervals (ef &amp; - &lt;f ^) and (eQ - where ef and &lt;Γ £ = cf,], a new torque signal value F based on the output values ​​cC the determination of a torque point. The employed value is determined according to the third characteristic yj, which goes through the last determined torque point &lt;T j ^^ / F ^^^ which in Fig. Aniaqeo be the point. As an example, in the figure the employed torque signal value Fp corresponding to a point P is shown. Then it is determined in a condition block 14 whether the input cT ^ is greater or less than zero to determine, depending on the range of the regions A 'B' D * C * A¹ and E'L'H'G'E ', which the calculation will continue. According to blocks 15 and 16, for the current input value jf θη moment point M is determined on the first characteristic y 'and a mornings point N on the second characteristic y' '. These points correspond to a torque signal value Ε ^ χ and E ^ respectively.

In two condition blocks 17 and 18, the applied torque signal value ^ TQ <is determined^FP> greater than the signal value F | ^^, less than the signal value or between these signal values. In the latter case, which corresponds to the torque point being in the area between the first and second characteristics, the applied torque signal value is correct and maintained. Thus, the determined torque point is on a third characteristic y '. According to a block 19, current input and signal signal values ​​are also used as output values ​​for determining the next torque signal value, which is done by returning from a block 20 to a starting block 27. This determination of the torque signal value occurs. with predetermined frequency. In the current application, a frequency of about 100 Hz has been found sufficient to update the torque signal value.

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If the applied torque signal value F. is greater than the signal value, i.e. the applied torque point is Above the first characteristic y ', as shown in Fig. 3, in a block 21 the torque signal value is set to F

MAX

If the applied torque signal value F ^ is less than the signal value F,, i.e. the applied torque point is below the second characteristic y 'is determined in a block 22 torque signal value to F

According to a block 23, the input signal value and the final torque signal value ^ AX MIN MIN are also used in these cases. ^As output values ​​for determining the next torque signal value.

Thus, in the two latter cases where the blocks 21 and 22 come into use, the determined torque point will lie on either the first or second characteristic y₂·

If, according to block 10, the input signal is less than the signal value df, in a block 24, the torque signal value F ^ is set equal to the signal value F ^ at the point A '. As output values ​​for determining the next torque point, the signal values ​​£ and F are used_ft for point A '.

If, according to block 11, the input signal is greater than the signal value, a torque signal value is determined in a block 25 depending on the fifth characteristic y '. As the output values ​​for determining the next torque point, the signal values ​​J h and F

According to block 12, the input signal is less than is between and determined in block 26 the torque signal value in dependence of the fourth characteristic y '. As the output values ​​for determining the next torque point, the input signal value zero and the torque signal value zero are used.

By means of the invention, it is possible in manual control by means of an actuator to achieve a rapid coarse control of the controlled means with moderate actuator torques, while local fine control with increased torque gradient can be achieved around each display position of the actuator.

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This enables extremely comfortable and efficient movements and, in fine control, precise movements for the control hand and thus better control performance than previously possible. The locally elevated moomin gradient of the control system determined by a third characteristic is fully space oriented, ie. solely dependent on the actuator's display. The invention is also easy to apply and does not suffer from time-dependent side effects. In addition, the risk of operator-induced oscillations is reduced.

In the description above, the torque motor alone has accounted for the actuating lever display counteracting the torque. However, for practical reasons and for safety reasons it is appropriate to use a mechanical spring (not shown) together with the torque motor to generate a basic torque acting on the control lever, which together with the torque motor torque gives a total desired torque, which can then correspond to the torque diagram in FIG. 3. This spring torque is shown in Fig. 3 dashed as a broken line F. In such a case, the characteristics used for the operation of the torque motor may have a significantly smaller slope. In the case shown in Fig. 3, the characteristics y 'and y' will be horizontal and have the torque gradient zero.

Although the invention has been described with reference to a sensor in particular for determining the display position of the actuator, it includes all embodiments in which a sensor is utilized for determining also a magnitude dependent on the display position, e.g. the force acting on the actuator.

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