JP2009067073A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of realizing good steering returning characteristic and steering feeling, regardless of vehicle speed and steering angle. <P>SOLUTION: A steering returning control portion changes the steering returning characteristic shown in a two-axis coordinate system of steering angle and steering speed target value based on the vehicle speed. The change of the steering returning characteristic based on the vehicle speed is performed by scaling (expansion and contraction) in a steering angle coordinate direction of the two-axis coordinate system showing the steering returning characteristic. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus.

  In recent years, electric power steering devices (EPS) using a motor as a drive source have been widely adopted as vehicle power steering devices. In many of these EPSs, steering return control (steering return compensation control) for returning the steering to the neutral position is performed as one of the compensation controls.

  In other words, if the vehicle is traveling, the steering should theoretically return to the neutral position (zero steering angle) by the self-aligning torque acting on the steered wheels without performing any special steering operation. However, in the case of EPS, the friction of the system, for example, the friction of the speed reduction mechanism (ball screw, worm & wheel, etc.) may exceed the self-aligning torque that acts on the steered wheels as described above. May not return to the neutral position.

  Therefore, the compensation component (steering return compensation amount) acting in the steering neutral direction is calculated by executing the steering return control as described above. For example, the EPS described in Patent Literature 1 calculates a compensation component for executing steering return control by executing feedback control based on a deviation between a steering speed target value calculated based on a steering angle and an actual steering speed. . By superimposing the compensation component on the basic assist control amount, which is the basic component of power assist control, the steering can be quickly returned to the neutral position, and the steering performance is good regardless of the road surface condition. It is possible to ensure.

Further, in this EPS, a multiplication coefficient whose value increases as the vehicle speed increases is calculated, and a compensation component for executing the steering return control is calculated by multiplying the basic control amount by the multiplication coefficient ( (See Patent Document 1 and FIG. 5). That is, in normal steering, the range of the steering angle actually generated, that is, the effective steering angle range changes according to the vehicle speed, and narrows as the vehicle speed increases. In other words, since only a very small steering angle is generated during high speed traveling, the returnability of the steering tends to deteriorate. Therefore, during such high speed running, the steering return control is strengthened to improve the return of the steering.
JP 2006-123827 A

  By the way, the assist force (steering reaction force) applied to the steering system as a steering return force is basically increased as the steering angle (absolute value thereof) is increased. There is an upper limit. For this reason, normally, the compensation component in the steering return control (the steering speed target value in the case of speed feedback) gradually increases with the increase of the steering angle so as not to exceed the upper limit of the appropriate value. Reduction (see Patent Document 1, FIG. 4). Alternatively, as shown in FIG. 8, in a large rudder angle region exceeding a predetermined angle, it is general that the upper limit value (−ω0 or ω0) is constant (in FIG. 8, the horizontal axis indicates steering). The angle indicates the steering speed target value on the vertical axis).

  However, as in the above-described conventional example, in the configuration in which the steering return control is strengthened by calculating the multiplication coefficient that increases with the vehicle speed and multiplying this by the basic control amount, the effective steering angle according to the vehicle speed as described above. Although the range changes, the steering speed target value (steering return compensation amount) is increased in all the steering angle regions. Therefore, as shown in FIG. 8, when the effective steering angle range is narrowed as the vehicle speed increases, the steering speed target value exceeding the upper limit value (−ω0 or ω0) considered to be an appropriate value, that is, steering. There is a problem that the amount of return compensation is calculated, which in turn may lead to deterioration of the steering feeling.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric power steering device capable of realizing good steering return and steering feeling regardless of the vehicle speed and steering angle. Is to provide.

  In order to solve the above problems, the invention according to claim 1 is directed to a steering force assisting device for applying an assist force for assisting a steering operation to a steering system, and the steering force assisting device based on an assist force target value. The assist force target value calculated by the control means includes a compensation component for executing steering return control, and the compensation component is calculated based on the steering angle. The control means is calculated by executing feedback control based on a deviation between a steering speed target value and an actual steering speed, and the control means has a biaxial coordinate system of the steering angle and the steering speed target value based on a vehicle speed. In the electric power steering apparatus that changes the steering return characteristic represented, the change of the steering return characteristic based on the vehicle speed is the steering return characteristic. Be performed by the steering angle coordinate direction of scaling in the two-axis coordinate system which represents the, and the gist.

  That is, by the scaling in the steering angle coordinate direction, the ratio of the change in the steering speed target value with respect to the change in the steering angle becomes large, that is, the gradient becomes steep, but the maximum value itself does not change. Therefore, according to the above configuration, it is possible to enhance the steering return control while preventing the generation of an excessive steering speed target value that exceeds an upper limit value that is considered to be appropriate as the steering speed generated when the steering is returned. As a result, it is possible to realize good steering return and steering feeling regardless of the vehicle speed and steering.

  According to a second aspect of the present invention, there is provided a steering force assisting device that applies an assist force for assisting a steering operation to a steering system, and a control unit that controls the operation of the steering force assisting device based on an assist force target value. The assist force target value calculated by the control means includes a compensation component for executing steering return control, and the compensation component is calculated based on a steering angle, and the control means In the electric power steering apparatus that changes the steering return characteristic represented in the biaxial coordinate system of the steering angle and the compensation component based on the vehicle speed, the change of the steering return characteristic based on the vehicle speed represents the steering return characteristic The gist of the present invention is that it is performed by scaling in the steering angle coordinate direction in the biaxial coordinate system.

  That is, due to the scaling in the steering angle coordinate direction, the ratio of the change in the compensation component with respect to the change in the steering angle becomes large, that is, the slope becomes steep, but the maximum value itself does not change. Therefore, according to the above configuration, it is possible to enhance the steering return control while preventing the generation of an excessive compensation component exceeding an upper limit value considered to be appropriate as the steering return force generated at the time of steering return. As a result, it is possible to realize good steering return and steering feeling regardless of the vehicle speed and steering.

  The gist of the invention described in claim 3 is that the scaling is performed based on a change in an effective steering angle range according to the vehicle speed. That is, the occurrence of an excessive steering speed target value (compensation component) exceeding the upper limit considered appropriate is manifested by narrowing of the effective steering angle range as the vehicle speed increases. Therefore, according to the above configuration, it is possible to more effectively prevent the excessive steering speed target value (compensation component) from being generated.

  According to the present invention, the present invention has been made to solve the above-mentioned problems, and the object thereof is to realize good steering return and steering feeling regardless of the vehicle speed and the steering angle. It is possible to provide an electric power steering device capable of achieving the above.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an electric power steering apparatus (EPS) 1 according to the present embodiment. As shown in the figure, the steering shaft 3 to which the steering wheel 2 is fixed is connected to a rack 5 via a rack and pinion mechanism 4, and the rotation of the steering shaft 3 accompanying the steering operation is performed by the rack and pinion mechanism 4. Is converted into a reciprocating linear motion of the rack 5. The steering angle of the steered wheels 6, that is, the steered angle is varied by the reciprocating linear motion of the rack 5, whereby the traveling direction of the vehicle is changed.

  The EPS 1 includes an EPS actuator 10 as a steering force assisting device that applies an assist force for assisting a steering operation to the steering system, and an ECU 11 as a control unit that controls the operation of the EPS actuator 10. .

  The EPS actuator 10 of the present embodiment is a so-called rack assist type EPS actuator in which a motor 12 as a driving source thereof is arranged coaxially with the rack 5, and the motor torque generated by the motor 12 is a ball feed mechanism (not shown). ) Is transmitted to the rack 5. In addition, the motor 12 of this embodiment is a brushless motor, and rotates by receiving supply of three-phase (U, V, W) driving power from the ECU 11.

  On the other hand, the ECU 11 is connected to a plurality of sensors for detecting various state quantities such as the torque sensor 14 and the vehicle speed sensor 15, and the ECU 11 detects the state quantities detected by these sensors, that is, steering. An assist force target value (target assist force) is calculated based on the torque τ and the vehicle speed V (and a steering angle θs and a steering speed ωs described later) and the like. Then, in order to generate the target assist force in the EPS actuator 10, the operation of the EPS actuator 10, that is, the assist force applied to the steering system is controlled through the supply of drive power to the motor 12 that is the drive source.

Next, an aspect of assist control in the EPS of the present embodiment will be described.
As shown in FIG. 2, the ECU 11 includes a microcomputer 21 that outputs a motor control signal, and a drive circuit 22 that supplies drive power to the motor 12 that is a drive source of the EPS actuator 10 based on the motor control signal. ing.

  In the present embodiment, the ECU 11 is connected to a current sensor 23 for detecting an actual current value I supplied to the motor 12 and a rotation angle sensor 24 for detecting the rotation angle θm of the motor 12. The microcomputer 21 outputs a motor control signal to the drive circuit 22 based on the actual current value I and the rotation angle θm of the motor 12 detected based on the output signals of these sensors, and the steering torque τ and the vehicle speed V. To do.

  Each control block in the microcomputer 21 shown below is realized by a computer program executed by the microcomputer 21. Then, the microcomputer 21 detects each state quantity at a predetermined sampling period, and generates a motor control signal by executing each arithmetic processing shown in the following control blocks at every predetermined period.

  Specifically, the microcomputer 21 includes a current command value calculation unit 25 that calculates a current command value Iq * corresponding to an assist force target value (target assist force) to be generated by the EPS actuator 10, and a current command value calculation unit 25. And a motor control signal output unit 26 that outputs a motor control signal based on the calculated current command value Iq *.

  The current command value calculation unit 25 of this embodiment includes a basic assist control unit 27 that calculates a basic assist control amount Ias *, which is a basic control component of the target assist force, and the steering 2 as a neutral component (θs Steering return controller 28 for calculating the steering return compensation amount Isb * for returning to (= 0).

  In this embodiment, the steering torque τ and the vehicle speed V are input to the basic assist control unit 27, and the basic assist control unit 27 performs the steering based on the steering torque τ and the vehicle speed V. The larger the torque τ and the smaller the vehicle speed V, the larger the basic assist control amount Ias * is calculated.

  On the other hand, the vehicle speed V, the steering angle θs, and the steering speed ωs are input to the steering return control unit 28. In the microcomputer 21 of the present embodiment, the steering angle calculation unit 29 calculates the steering angle θs based on the rotation angle θm of the motor 12 detected by the rotation angle sensor 24, and calculates the calculated steering angle θs. The steering speed ωs is calculated by differentiating. Then, the steering return control unit 28 calculates the steering return compensation amount Isb *, that is, a compensation component for generating the steering return force acting in the steering neutral direction based on these state quantities (steering return control). ).

  The basic assist control amount Ias * calculated by the basic assist control unit 27 and the steering return compensation amount Isb * calculated by the steering return control unit 28 are input to the adder 30. Then, the current command value calculation unit 25 calculates the current command value Iq * as the target assist force by superimposing the steering return compensation amount Isb * on the basic assist control amount Ias * in the adder 30, and the motor control The signal is output to the signal output unit 26.

  The motor control signal output unit 26 includes the current command value Iq * output from the current command value calculation unit 25, the actual current value I detected by the current sensor 23, and the rotation angle θm detected by the rotation angle sensor 24. Entered. The motor control signal output unit 26 calculates a motor control signal by executing feedback control so that the actual current value I follows the current command value Iq * corresponding to the target assist force.

  Specifically, in the present embodiment, the motor control signal output unit 26 converts the phase current value (Iu, Iv, Iw) of the motor 12 detected as the actual current value I into the d, q axes of the d / q coordinate system. The current feedback control is performed by converting into a current value (d / q conversion).

  That is, the current command value Iq * is input to the motor control signal output unit 26 as a q-axis current command value, and the motor control signal output unit 26 determines the phase current value based on the rotation angle θm detected by the rotation angle sensor 24. (Iu, Iv, Iw) is d / q converted. The motor control signal output unit 26 calculates the d and q axis voltage command values based on the d and q axis current values and the q axis current command value. Then, the phase voltage command values (Vu *, Vv *, Vw *) are calculated by performing d / q inverse conversion on the d and q axis voltage command values, and a motor control signal is generated based on the phase voltage command values. To do.

  In the ECU 11 of the present embodiment, the microcomputer 21 outputs the motor control signal generated as described above to the drive circuit 22, and the drive circuit 22 supplies the three-phase drive power based on the motor control signal to the motor 12. Is configured to control the operation of the EPS actuator 10.

[Steering return control]
Next, the configuration of the steering return control unit in this embodiment and the aspect of the steering return control will be described.

  As shown in FIG. 2, the steering return control unit 28 of the present embodiment includes a steering speed target value calculation unit 31, and the steering speed target value calculation unit 31 steers based on the steering angle θs and the vehicle speed V. The speed target value ωs * is calculated.

  Specifically, as shown in FIG. 3, the steering return control unit 28 according to the present embodiment has a larger absolute value as the detected absolute value of the steering angle θs increases, and the steering angle θs. A steering speed target value ωs * having a different sign is calculated (in the figure, the horizontal axis indicates the steering angle θs and the vertical axis indicates the steering speed target value ωs *). That is, the steering speed target value ωs * in the steering neutral direction is calculated.

  Here, in the present embodiment, an upper limit value (−ω0 or ω0) is set for the steering speed target value ωs * calculated by the steering return control unit 28. In a large steering angle region exceeding a predetermined angle (θ0 or −θ0), the value is constant at the upper limit value (−ω0 or ω0). In this case, the upper limit value (−ω0 or ω0) is set in correspondence with the upper limit of a value that is considered appropriate as the steering speed ωs generated when the steering returns. The predetermined angle (θ0 or −θ0) corresponding to the large steering angle region where the steering speed target value ωs * is constant at the upper limit value (−ω0 or ω0) is the steering that actually occurs in normal steering. It is set corresponding to the angle range, that is, the effective steering angle range.

  The steering speed target value ωs * calculated by the steering speed target value calculation unit 31 is input to the subtractor 32 together with the actual steering speed ωs, and the deviation Δωs calculated by the subtracter 32 is calculated by F / B control calculation. Is output to the unit 33. Then, the F / B control calculation unit 33 executes the feedback control calculation to cause the actual steering speed ωs to follow the steering speed target value ωs * based on the input deviation Δωs, whereby the steering return compensation is performed. A basic compensation amount ε_sb which is a basic component of the amount Isb * is calculated.

  Further, the steering return control unit 28 of the present embodiment is provided with a vehicle speed gain calculation unit 34, and the basic compensation amount ε_sb is multiplied by the vehicle speed gain Kv. The vehicle speed gain calculation unit 34 of the present embodiment sets the basic compensation amount ε_sb (that is, the steering return compensation amount Isb *) to “0” when the vehicle speed V is approximately “0”, that is, when the vehicle is in a stopped state. The vehicle speed gain Kv is calculated. In addition, the steering return control unit 28 of the present embodiment further performs filter processing in the filter processing unit 36 and guard processing in the guard processing unit 37 on the basic compensation amount ε_sb. The basic compensation amount ε_sb ′ after these processes are output to the adder 30 as the steering return compensation amount Isb *.

(Change of steering return characteristics based on vehicle speed)
As described above, when the vehicle travels at a high speed, only a very small steering angle is generated, so that the returnability of the steering tends to deteriorate. Therefore, it is desirable to strengthen the steering return control during such high speed traveling.

  However, as in the above-described conventional example, in the configuration in which the steering return control is strengthened by calculating the multiplication coefficient that increases with the vehicle speed and multiplying this by the basic control amount, the effective steering angle according to the vehicle speed as described above. Although the range changes, the steering speed target value (steering return compensation amount) is increased in all the steering angle regions. Therefore, when the effective steering angle range is narrowed as the vehicle speed increases, the steering speed target value exceeding the upper limit value (−ω0 or ω0) considered to be an appropriate value, that is, the steering return compensation amount is calculated. (See FIG. 8).

  In consideration of this point, in this embodiment, the steering return control according to the vehicle speed V is enhanced by changing the steering return characteristic represented in the biaxial coordinate system of the steering angle θs and the steering speed target value ωs *. Realize. The change of the steering return characteristic based on the vehicle speed V is performed by scaling (expansion / contraction) in the steering angle coordinate direction in the biaxial coordinate system representing the steering return characteristic.

  Specifically, as shown in FIG. 4, it is expressed in the biaxial coordinate system in accordance with the change in the effective steering angle range according to the vehicle speed V, that is, the effective steering angle range that narrows as the vehicle speed V increases. The steering return characteristic is reduced in the steering angle coordinate direction (see FIG. 3, left-right direction in the figure).

  In other words, the angle (θ0 or −θ0) at which the steering speed target value ωs * is constant at the upper limit value (−ω0 or ω0) that is considered to be appropriate by scaling in the steering angle coordinate direction is higher as the vehicle speed V is higher. Then, it moves to the steering neutral position (θs = 0) side. In the region in between, that is, the steering angle region (−θ0 ≦ θs ≦ θ0) in which the steering speed target value ωs * changes according to the steering angle θs, the change in the steering speed target value ωs * with respect to the change in the steering angle θs. The ratio changes to a large one, that is, its slope is steeper.

  In other words, by performing scaling only in the steering angle coordinate direction in the biaxial coordinate system representing the steering characteristics, it is possible to enhance the steering return control without changing the maximum value of the steering speed target value ωs * itself. it can. In the present embodiment, this prevents an excessive steering speed target value ωs * exceeding an upper limit value (−ω0 or ω0) that is considered appropriate as the steering speed ωs generated at the time of returning from the steering, thereby preventing the vehicle speed V or It is configured to achieve good steering return and steering feeling regardless of the steering angle θs.

  More specifically, as shown in FIG. 2, the steering speed target value calculation unit 31 according to the present embodiment responds to each vehicle speed for each predetermined vehicle speed (see FIG. 5, set vehicle speeds V0 to V6). A plurality of maps 40 (see FIG. 5, map numbers m0 to m6) storing the relationship between the steering angle θs and the steering speed target value ωs * in the biaxial coordinate system are provided. That is, each map 40 stores optimum steering characteristics at each set vehicle speed V0 to V6 obtained by scaling in the steering angle coordinate direction as described above (see FIG. 5). And the steering speed target value calculating part 31 of this embodiment performs the interpolation calculation (linear interpolation) based on these maps 40 and the input vehicle speed V. FIG.

  Specifically, as shown in FIG. 5, for example, when the detected vehicle speed V is a vehicle speed Va between the set vehicle speed V1 of the map number m1 and the set vehicle speed V2 of the map number m2, these two Select a map. Then, the vehicle speed interpolation ratio α is calculated by the following equation (1), and the equation (2) using the vehicle speed interpolation ratio α is solved to obtain the optimum steering speed according to the steering speed ωs and the vehicle speed V at that time. The target value ωs * is calculated.

α = (V−V_Lo) / (V_Hi−V_Lo) (1)
ωs * = ωs * _Lo + (ωs * _Lo−ωs * _Hi) × α (2)
However, V_Lo: Low vehicle speed side set vehicle speed, V_Hi: High vehicle speed side set vehicle speed, ωs * _Lo: Low vehicle speed side search value, ωs * _Hi: High vehicle speed side search value.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The steering return control unit 28 executes the feedback control based on the deviation Δωs between the steering speed target value ωs * and the actual steering speed ωs, thereby obtaining the basic compensation amount ε_sb that is a basic component of the steering return compensation amount Isb *. Calculate. Further, the steering return control unit 28 changes the steering return characteristic represented in the biaxial coordinate system of the steering angle θs and the steering speed target value ωs * based on the vehicle speed V. The change of the steering return characteristic based on the vehicle speed V is performed by scaling (enlargement / reduction) in the steering angle coordinate direction in the biaxial coordinate system representing the steering return characteristic.

  That is, by the scaling in the steering angle coordinate direction, the rate of change of the steering speed target value ωs * with respect to the change of the steering angle θs becomes large, that is, the gradient becomes steep, but the maximum value itself does not change. Therefore, according to the above configuration, the steering return control is performed while preventing the generation of an excessive steering speed target value ωs * exceeding the upper limit value (−ω0 or ω0) considered to be appropriate as the steering speed ωs generated at the time of steering return. Can be strengthened. As a result, it is possible to realize good steering return and steering feeling regardless of the vehicle speed V and the steering angle θs.

  (2) Scaling is performed based on a change in the effective steering angle range according to the vehicle speed. That is, the occurrence of an excessive steering speed target value ωs * exceeding the upper limit considered appropriate is manifested by the narrowing of the effective steering angle range as the vehicle speed increases. Therefore, according to the above configuration, the generation of the excessive steering speed target value ωs * can be more effectively prevented.

In addition, you may change this embodiment as follows.
In this embodiment, the present invention is a steering return compensation amount that is a compensation component for executing the steering return control by executing the feedback control based on the deviation Δωs between the steering speed target value ωs * and the actual steering speed ωs. The present invention is applied to a configuration for calculating Isb * (basic compensation amount ε_sb). However, the present invention is not limited to this. For example, as shown in FIG. 6, the present invention is applied to a device that directly calculates the steering return compensation amount Isb * based on the steering angle θs without executing the steering speed feedback control. May be.

  In the figure, the horizontal axis represents the steering angle θs, and the vertical axis represents the steering return compensation amount Isb *. “Isb0 (−Isb0)” on the vertical axis indicates a steering return compensation amount Isb * corresponding to an upper limit value (−ω0 or ω0) considered to be appropriate as the steering speed ωs generated at the time of steering return.

  That is, the steering return characteristic represented in the biaxial coordinate system of the steering angle θs and the steering return compensation amount Isb * is changed according to the vehicle speed V. The steering return characteristic may be changed by scaling in the steering angle coordinate direction in the biaxial coordinate system representing the steering return characteristic. Needless to say, the steering return compensation amount Isb * in this case may correspond to the basic component, that is, the basic compensation amount ε_sb in the present embodiment.

  In the present embodiment, the vehicle speed gain Kv multiplied by the basic compensation amount ε_sb is set such that the basic compensation amount ε_sb (that is, the steering return compensation amount Isb *) is “0” when the vehicle is in a stopped state (substantially V = 0). " However, the present invention is not limited to this. For example, as shown in FIG. 7, the steering return compensation amount Isb * having a large value (absolute value) is output at a low vehicle speed, and the value ( The vehicle speed gain Kv for correcting the basic compensation amount ε_sb may be calculated so that the steering return compensation amount Isb * with a small absolute value is output.

  In the present embodiment, the steering angle θs and the steering speed ωs are calculated based on the rotation angle θm of the motor 12 that is the drive source of the EPS actuator 10, but are detected by a so-called steering sensor provided near the steering. It may be done.

  In the present embodiment, in a large steering angle region exceeding a predetermined angle (θ0 or −θ0), an upper limit value (−ω0) that the value of the steering speed target value ωs * is considered appropriate as the steering speed ωs generated when the steering returns. Or ω 0) (see FIG. 3). However, the present invention is not limited to this, and, for example, as described in Patent Document 1 (FIG. 4), the increase width associated with the increase in the steering angle may be gradually reduced so as not to exceed the upper limit.

The schematic block diagram of an electric power steering device (EPS). The control block diagram of EPS. Explanatory drawing of the steering return characteristic represented by the biaxial coordinate system of a steering angle and a steering speed target value. Explanatory drawing which shows the aspect of a change of the steering return characteristics by scaling of the steering angle coordinate direction in a biaxial coordinate system. Explanatory drawing which shows the aspect of the interpolation calculation (linear interpolation) based on a vehicle speed. Explanatory drawing of the steering return characteristic represented by the biaxial coordinate system of a steering angle and a steering return compensation amount. The wave form diagram which shows the characteristic of the vehicle speed gain of another example. Explanatory drawing which shows generation | occurrence | production of the excessive steering speed target value resulting from narrowing of the effective steering angle range accompanying the raise of a vehicle speed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 2 ... Steering, 6 ... Steering wheel, 10 ... EPS actuator, 11 ... ECU, 12 ... Motor, 21 ... Microcomputer, 22 ... Drive circuit, 25 ... Current command value calculating part, 27 DESCRIPTION OF SYMBOLS ... Basic assist control part, 28 ... Steering return control part, 30 ... Adder, 31 ... Steering speed target value calculating part, 32 ... Subtractor, 33 ... F / B control calculating part, Iq * ... Current command value, Ias * ... basic assist control amount, Isb * ... steering return compensation amount, ε_sb, ε_sb '... basic control amount, V ... vehicle speed, θs ... steering angle, ωs ... steering speed, ωs * ... steering speed target value, Δωs ... deviation, ω0 (-Ω0) ... Upper limit value.

Claims (3)

A steering force assisting device for applying an assist force for assisting a steering operation to the steering system, and a control means for controlling the operation of the steering force assisting device based on an assist force target value, are calculated by the control means. The assist force target value includes a compensation component for executing steering return control, and the compensation component executes feedback control based on a deviation between a steering speed target value calculated based on a steering angle and an actual steering speed. In the electric power steering apparatus that changes the steering return characteristic represented in the biaxial coordinate system of the steering angle and the steering speed target value based on the vehicle speed,
The change of the steering return characteristic based on the vehicle speed is performed by scaling in the steering angle coordinate direction in the biaxial coordinate system representing the steering return characteristic.
An electric power steering device. A steering force assisting device for applying an assist force for assisting a steering operation to the steering system, and a control means for controlling the operation of the steering force assisting device based on an assist force target value, are calculated by the control means. The assist force target value includes a compensation component for executing steering return control, and the compensation component is calculated based on a steering angle, and the control means is configured to control the steering angle and the In the electric power steering apparatus that changes the steering return characteristic represented in the biaxial coordinate system of the compensation component,
The change of the steering return characteristic based on the vehicle speed is performed by scaling in the steering angle coordinate direction in the biaxial coordinate system representing the steering return characteristic.
An electric power steering device. In the electric power steering device according to claim 1 or 2,
The scaling is performed based on a change in an effective steering angle range according to the vehicle speed;
An electric power steering device.

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