JP2009262622A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device suppressing overshoot of steering speed feedback control in shifting from a steering holding state to a hand-off state to improve its follow-up performance. <P>SOLUTION: A steering return control part 28 computes a steering return control quantity Isb* as a compensation component for returning steering into a neutral position by carrying out the steering speed feedback control to allow an actual steering speed ωs to follow a steering speed target value ωs*. The steering return control part 28 has a function of determining the state of steering operation. When determining that the state of steering operation is in a shift time from the steering holding state to the hand-off state, the steering return control quantity Isb* to be output is reduced. <P>COPYRIGHT: (C)2010,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 such EPSs, steering return control (steering wheel return compensation control) for smoothly 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 acting on the steered wheels as described above. May not return to the neutral position.

  Therefore, the compensation component (steering return control amount) acting in the steering neutral direction is calculated by executing the steering returning control. 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 the composition which secures.

Further, the self-aligning torque that acts on the steered wheels changes according to the vehicle speed and the steering angle. Therefore, depending on the running state of the vehicle, the steering speed at the time of returning the steering may become excessive due to the self-aligning torque. In view of this point, in the EPS described in Patent Document 1, the steering speed target value in the steering return control is set to be lower for the large steering angle region in which the steering speed at the time of returning the steering is likely to be excessive. (See FIG. 4). Then, the above-described feedback control is executed to make the actual steering speed follow the steering speed target value, thereby correcting the target.
JP 2006-123827 A

  However, in reality, there are situations where the steering speed is likely to be excessive other than when the steering is returned from the large steering angle region as described above, and it cannot be said that the prior art is effective for all of them. Is the actual situation. In particular, when the vehicle is returned from the steady turning state to the straight traveling state, excessive steering speed may be promoted by executing the steering speed feedback control.

  That is, when returning from steady turning to straight running, the steering operation state shifts from a steered state to a so-called hand-off state, that is, a state in which substantially no steering torque is input. At this time, in order to increase the steering speed from substantially “zero” to the steering speed target value, a large compensation component is calculated in the steering return direction by the steering speed feedback control, while the basis for maintaining the steering angle is calculated. The component is “substantially zero”.

  In other words, at the time of transition from the steered state to the released state, the steering speed is rapidly increased by superimposing the large compensation component on the self-aligning torque without being reduced to the basic component having the value in the steering angle direction. To rise. As a result, there is a problem that the steering speed exceeds the steering speed target value, that is, an overshoot occurs, resulting in a delay in the follow-up. In this respect, there is still room for improvement. It was.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to suppress overshoot of the steering speed feedback control at the time of transition from the steered state to the hand-off state and improve its followability. An object of the present invention is to provide an electric power steering apparatus capable of achieving the above.

  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. And the assist force target value calculated by the control means includes a compensation component for executing steering return control, and the compensation component includes a steering speed target value and an actual value. An electric power steering apparatus that is calculated by executing feedback control based on a deviation from a steering speed, wherein the control means, when the steering operation state shifts from a steered state to a released state, The gist is to reduce the compensation component for executing the return control.

  That is, at the time of transition from the steered state to the released state, the compensation component for executing the steering return control becomes a large value, so that the steering speed rapidly increases. And since the rise is steep, the amount of overshoot is also large. In particular, in the case where the integral control is executed as the steering speed feedback control, the influence due to the accumulation of the deviation becomes more prominent as the steered state lasts longer. However, according to the above configuration, it is possible to make the rising of the steering speed gentle when shifting from the steered state to the released state. As a result, the occurrence of overshoot can be suppressed and followability can be improved.

The gist of the invention described in claim 2 is that the reduction of the compensation component is continued until the steering speed target value and the actual steering speed first become the same value.
That is, a certain amount of overshoot occurs even when the compensation component is reduced. However, according to the above configuration, the generated overshoot can be quickly converged.

The gist of the invention described in claim 3 is that the suppression of the compensation component is performed from the time when the state of the steering operation is in the holding state.
According to the above configuration, it is possible to reduce the calculation load and suppress an increase in cost caused by the enhancement of the processing capability of the calculation means. Further, since the control component in the return direction is reduced, the steering angle can be easily maintained, and the burden on the driver at the time of steering can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power steering apparatus which can suppress the overshoot of steering speed feedback control at the time of transfer to a hand-off state from a steering holding state, and can aim at the improvement in the followability can be provided.

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 with a plurality of sensors for detecting various state quantities such as a torque sensor 14, a vehicle speed sensor 15, and a steering sensor (steering angle sensor) 16, and the ECU 11 The assist force target value (target assist force) is calculated based on the state quantity detected by the sensor, that is, the steering torque τ, the vehicle speed V, the steering angle θs (and the steering speed ωs), and the like. Then, the ECU 11 operates the EPS actuator 10, that is, assist force applied to the steering system through supply of drive power to the motor 12 as a drive source in order to cause the EPS actuator 10 to generate the calculated target assist force. To control.

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. Then, the microcomputer 21 drives 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, the vehicle speed V, the steering angle θs, and the steering speed ωs. A motor control signal is output to the circuit 22.

  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 control unit 28 for calculating a steering return control 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 and the steering angle θs are input to the steering return control unit 28. Then, the steering return control unit 28 calculates the steering return control amount Isb *, that is, a compensation component for generating the steering return force acting in the steering neutral direction based on each of these state quantities (steering return control). ).

  Specifically, the steering return control unit 28 of the present embodiment sets the actual steering speed ωs to the steering speed target value ωs * calculated based on the steering angle θs detected by the steering sensor 16 (see FIG. 1). The steering return control amount Isb * is calculated by executing the steering speed feedback control so as to follow. In the present embodiment, the steering speed ωs is obtained by differentiating the steering angle θs.

  More specifically, the steering angle θs input to the steering return control unit 28 is input to the steering speed target value calculation unit 29, and the steering speed target value calculation unit 29 calculates the steering speed target value ωs *. . Specifically, the steering return control unit 28 of the present embodiment includes a map 29a in which the steering angle θs and the steering speed target value ωs * are associated (see FIG. 3, steering speed target value calculation map). In the map 29a, the steering speed target value ωs * is set to be a value in the return direction having a larger absolute value as the absolute value of the steering angle θs is larger (as the steering angle is larger). Then, the steering speed target value calculation unit 29 refers to the input steering angle θs to the map 29a, that is, calculates the steering speed target value ωs * by executing the map calculation using the map 29a.

  The steering speed target value ωs * calculated by the steering speed target value calculation unit 29 is input to the subtracter 30 together with the steering speed ωs, and the subtracter 30 calculates the steering speed target value ωs * and the actual steering speed ωs. A deviation between them (steering speed deviation Δωs) is calculated. The F / B control calculation unit 31 calculates a basic control amount εsb, which is a basic component of the steering return control amount Isb *, by multiplying the steering speed deviation Δωs by a predetermined gain.

  The vehicle speed V is input to the vehicle speed gain calculation unit 32, and the vehicle speed gain calculation unit 32 calculates a larger vehicle speed gain Kv as the vehicle speed V increases (see FIG. 4). Then, the steering return control unit 28 of the present embodiment uses the multiplier 33 to calculate the basic control amount εsb calculated by the F / B control calculation unit 31 (the basis after being corrected in the steering correction calculation unit 35 described later). A value obtained by multiplying the control amount εsb ′) by the vehicle speed gain Kv is output as a steering return control amount Isb *.

  The basic assist control amount Ias * calculated by the basic assist control unit 27 and the steering return control amount Isb * calculated by the steering return control unit 28 are input to the adder 34. Then, the current command value calculation unit 25 superimposes the steering return control amount Isb * on the basic assist control amount Ias * in the adder 34, thereby the current command value Iq * as the assist force target value (target assist force). Is output to the motor control 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.

(Reduction control of the steering return control amount at the time of transition from the steered state to the released state)
Next, the steering return control amount reduction control in this embodiment will be described.
As described above, at the time of transition from the steered state to the released state, the steering return control amount Isb * having a large value in the steering return direction is calculated by the steering speed feedback control, while the steering angle is maintained. Therefore, the basic assist control amount Ias *, which is a basic component, is “substantially zero”. In other words, at the time of transition from the holding state to the hand-off state, the steering return control amount Isb * having a large value is superimposed on the self-aligning torque without being reduced by the basic assist control amount Ias * having a value in the steering angle direction. As a result, the steering speed ωs increases rapidly. As a result, there is a problem that the steering speed ωs exceeds the steering speed target value ωs *, that is, an overshoot occurs, that is, the follow-up is delayed.

  In consideration of this point, the steering return control unit 28 of the present embodiment outputs the steering return control amount Isb that is output when it is determined that the state of the steering operation is a transition from the steered state to the released state. * Is reduced (see FIG. 5).

  That is, as shown in FIG. 6, at the time of transition from the steered state to the hand-off state, the steering speed ω is rapidly increased by outputting the steering return control amount Isb * having a large value. Since the rising edge is steep, the amount of overshoot is also large (the waveform shown by the one-dot chain line in the figure). In this respect, the rise of the steering speed ωs can be made gentle by reducing the steering return control amount Isb * at the time of transition from the steered state to the released state. And in this embodiment, it becomes the structure which suppresses generation | occurrence | production of an overshoot and improves follow-up property by this.

  More specifically, as shown in FIG. 2, in the steering return control unit 28 of this embodiment, a steering correction calculation unit 35 is interposed between the F / B control calculation unit 31 and the multiplier 33. . A steering torque τ, a vehicle speed V, a steering speed ωs, and a steering speed deviation Δωs are input to the steering correction calculation unit 35 together with the basic control amount εsb output from the F / B control calculation unit 31. The steered wheel correction calculation unit 35 has a function of determining the state of the steering operation based on these state quantities. When the steering correction calculation unit 35 determines that the steering state is a transition from the steering holding state to the release state, the basic control amount εsb input from the F / B control calculation unit 31 is determined. The corrected basic control amount εsb ′ whose value is reduced is output to the multiplier 33.

  More specifically, as shown in the flowchart of FIG. 7, the steering correction calculation unit 35 first performs the steering state determination (step 101). Specifically, as shown in the flowchart of FIG. 8, the steering correction calculation unit 35 determines whether or not the steering speed ωs (absolute value thereof) is equal to or less than a predetermined threshold value ω0 (step 201). It is then determined whether or not the steering torque τ (absolute value) is equal to or greater than a predetermined threshold value τ1 (step 202). When the steering speed ωs is equal to or lower than a predetermined threshold ω0 (ωs ≦ ω0, step 201: YES) and the steering torque τ is equal to or higher than the predetermined threshold τ1 (τ ≧ τ1, step 202: YES), It is determined that the steering state is the steering holding state (step 203). That is, it is determined that the steering is maintained when the steering torque τ is input even though the steering 2 is not substantially rotated. When the steering speed ωs exceeds the predetermined threshold ω0 (ωs> ω0, step 201: NO), or when the steering torque τ does not satisfy the predetermined threshold τ1 (τ <τ1, step 202: NO), the maintenance is performed. The rudder correction calculation unit 35 determines that the steering state is not the steered state (non-steered state, step 204).

  Next, the steering correction calculation unit 35 determines whether or not the result of the steering state determination is “steering state” (step 102), and when it is in the steering state (step 102: YES). "Turns ON (set)" the steering flag (step 103). Further, it is determined whether or not the correction flag is “ON” (step 104). If the correction flag is “ON” (step 104: YES), the correction flag is set to “OFF ( Reset) "(step 105). In step 104, when the correction flag is “OFF” (step 104: NO), the process of step 105 is not executed.

  On the other hand, when the result of the steered state determination in step 101 is “non-steered state” in step 102 (step 102: NO), the steered correction calculating unit 35 subsequently performs the hand release state determination. (Step 106). Specifically, as shown in the flowchart of FIG. 9, the steering correction calculation unit 35 determines whether or not the steering torque τ (absolute value thereof) is equal to or less than a predetermined threshold τ2 (step 301). When the steering torque τ is equal to or less than the predetermined threshold τ2 (τ ≦ τ2, step 301: YES), it is determined that the steering state is a let-off state (step 302), and exceeds the predetermined threshold τ2. In the case (τ> τ2, step 301: NO), it is determined that the steering state is not the let-off state (non-hand-off state, step 303).

  Next, the steering correction calculation unit 35 determines whether or not the result of the release state determination is “release state” (step 107), and determines that the release state is “release state” (step 107: YES). Then, it is determined whether or not the steering flag is “ON” (step 108). When the steering flag is “ON” (step 108: YES), the steering flag is “OFF” (step 109), and the correction flag is “ON” (step 110).

  In other words, the situation where the steering flag is still “ON” even though it is in the hand-off state is immediately after the shift from the steering state to the hand-off state. In such a case, the steering maintenance correction calculation unit 35 of the present embodiment corrects the basic control amount εsb input from the F / B control calculation unit 31, that is, the basic compensation amount correction calculation. Is executed (started) (step 111).

  Specifically, as shown in the flowchart of FIG. 10, in the basic compensation amount correction calculation, the steering correction calculation unit 35 first calculates the correction amount β for reducing the basic control amount εsb (step 401). . In the present embodiment, the correction amount β is calculated by multiplying the input basic control amount εsb (absolute value thereof) by the correction gain K (β = | εsb | × K). Note that the vehicle speed V is input to the steering correction calculation unit 35 of the present embodiment, and the correction gain K is calculated based on the vehicle speed V. Then, the steering correction calculation unit 35 adds or subtracts the correction amount β obtained in step 401 to the basic control amount εsb according to the sign of the input basic control amount εsb (εsb ′ = (εsb + β or εsb−β), that is, by offsetting, a correction amount correction calculation is executed to reduce the corrected value (step 402).

  In the present embodiment, following the correction amount correction calculation in step 402, a guard processing calculation for preventing sign inversion and suppressing a rapid change in the basic control amount εsb (εsb ′) to be output is performed. It is executed (step 403). The steering correction calculation unit 35 of the present embodiment is configured to output the corrected basic control amount εsb ′ subjected to the guard process to the multiplier 33 (step 404).

  If the steering flag is “OFF” in step 108 (step 108: NO), the steering correction calculator 35 next determines whether or not the correction flag is “ON” (step 108). Step 112). In step 112, if the correction flag is “ON” (step 112), it is further determined whether or not the steering speed deviation Δωs (absolute value) is equal to or smaller than a predetermined threshold value α (step 112). 113). The threshold value α is set to a value near “0”. When the steering speed deviation Δωs exceeds the predetermined threshold α (| Δωs |> α, Step 113: NO), the basic compensation amount correction calculation in Step 111 is executed, and the steering speed deviation Δωs is determined to be the predetermined threshold α. In the following case (| Δωs | ≦ α, Step 113: YES), the correction flag is set to “OFF” without executing the processing of Step 111 (Step 114).

  In other words, the situation where the correction flag is “ON” in the hand-off state means that the basic compensation amount correction calculation in step 111 has already been executed in the previous calculation cycle, that is, the steering return control amount Isb * is reduced. Correction control is being executed. Then, in this case, the steering correction calculation unit 35 of the present embodiment first catches up with the steering speed target value ωs * when the steering speed deviation Δωs first becomes substantially “0”, that is, the actual steering speed ωs catches up with the steering speed target value ωs *. The correction control is continued until the value becomes substantially the same.

  In step 112, the situation where the correction flag is “OFF” is after the shift from the steered state to the hand-off state and after the correction control has already been completed in order to reduce the steering return control amount Isb *. In such a case, the steering correction calculation unit 35 of the present embodiment does not execute the processing of step 113 and step 114 described above.

  In addition, the situation (step 107: NO) that is determined not to be in the “hand-off state” in step 107 is a case where the steered state has been released but has not shifted to the hand-off state. In such a case, first, the steering correction calculation unit 35 determines whether or not the steering flag is “ON” (step 115), and when the steering flag is “ON” (step 115: If YES, the steering flag is turned “OFF” (step 116). Further, it is determined whether or not the correction flag is “ON” (step 117). If the correction flag is “ON” (step 117: YES), the correction flag is turned “OFF”. (Step 118).

  As described above, the steering correction calculation unit 35 of the present embodiment repeatedly executes the processing of Step 101 to Step 118 at a predetermined calculation cycle. As a result, reduction control of the steering return control amount Isb * at the time of transition from the steered state to the released state is performed.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) When it is determined that the steering operation state is the transition from the steered state to the hand-off state, the steering return control unit 28 reduces the steering return control amount Isb * that is output.

  That is, when the steering state is shifted to the hand-off state, the steering return control amount Isb * having a large value is output, so that the steering speed ωs rapidly increases. And since the rise is steep, the amount of overshoot is also large. However, according to the above configuration, the steering speed ωs can be moderately raised at the time of transition from the steered state to the released state. As a result, the occurrence of overshoot can be suppressed and followability can be improved.

  (2) The steering return control unit 28 (steering correction calculation unit 35) first catches up with the steering speed target value ωs * when the steering speed deviation Δωs first becomes substantially “0”, that is, the actual steering speed ωs catches up with the steering speed target value ωs *. The steering return control amount Isb * that is output is continuously reduced until the values become substantially equal.

  That is, a certain amount of overshoot occurs even when the steering return control amount Isb * is reduced. However, as described above, the actual steering speed ωs catches up with the steering speed target value ωs *, and the reduction of the steering return control amount Isb * is canceled at a timing when the actual steering speed becomes approximately the same value first. Overshoot can be quickly converged.

In addition, you may change this embodiment as follows.
In the present embodiment, the holding state determination is executed based on the steering speed ωs and the steering torque τ (see FIG. 8), and the hand release state determination is executed based on the steering torque τ (see FIG. 9). However, the present invention is not limited to this, and each of these determinations may be performed by a method other than the above, for example, a hand release state determination using a pressure sensitive element is adopted.

  -In the present embodiment, at the time of transition from the steered state to the hand-off state, the reduction of the steering return control amount Isb * is started after releasing the steered state. It is good also as a structure performed from a certain time. Thereby, the calculation load is reduced. Further, since the control component in the return direction is reduced, it is easy to maintain the rudder angle, and the burden on the driver can be reduced.

  In the present embodiment, the reduction of the steering return control amount Isb * is canceled at the timing when the actual steering speed ωs catches up with the steering speed target value ωs * and becomes substantially the same value first. However, the present invention is not limited to this. For example, the reduction of the steering return control amount Isb * may be canceled when a predetermined time elapses.

  In the present embodiment, the steering return control amount Isb * is reduced by adding or subtracting, that is, offsetting, the basic control amount εsb according to the sign of the basic control amount εsb that is the basis thereof. (See FIG. 10, step 402). However, the configuration is not limited to this, and the absolute value may be limited within a predetermined range.

  Specifically, for example, as shown in the flowchart of FIG. 11, the steering correction calculation unit 35 calculates the absolute value of the input basic control amount εsb in the basic control amount correction calculation (see FIG. 7, step 111). It is determined whether or not the value exceeds a predetermined threshold value ε0 (step 501). If the absolute value exceeds the predetermined threshold value ε0 (| εsb |> ε0, step 501: YES), the corrected basic control amount εsb ′ is corrected so that the absolute value becomes the threshold value ε0. It is good also as a structure to perform (step 502). In this case, the sign may be matched with the sign before correction (εsb ′ = + εsb or −εsb). Even with such a configuration, the same effects as in the present embodiment can be obtained.

  In the present embodiment, inversion of the sign is prevented by the guard process shown in step 403 in the basic control amount correction calculation. However, the present invention is not necessarily limited to this. For example, due to the offset, the actual steering speed ωs catches up with the steering speed target value ωs * and is earlier than the timing at which it first becomes substantially the same value. Can be output. As a result, the amount of overshoot can be further reduced.

Next, technical ideas that can be grasped from the above embodiments will be described.
(Appendix 1) In the electric power steering apparatus according to any one of claims 1 to 3, the reduction of the compensation component is performed by offsetting the value of the calculated compensation component. Electric power steering device.

  (Appendix 2) In the electric power steering apparatus according to any one of claims 1 to 3, the compensation component is reduced by limiting a value of the compensation component to be calculated within a predetermined range. An electric power steering device characterized by that.

The schematic block diagram of an electric power steering device (EPS). The control block diagram of EPS. Explanatory drawing which shows the aspect of steering speed target value calculation. Explanatory drawing which shows the aspect of a vehicle speed gain calculation. Explanatory drawing which shows the aspect of reduction control of the steering | stirring return control amount at the time of transfer to a hand-off state from a steering holding state. Explanatory drawing which shows transition of the steering speed at the time of the transition from a steering holding state to a hand-off state. The flowchart which shows the process sequence of reduction control of a steering | stirring return control amount. The flowchart which shows the process sequence of steering maintenance state determination. The flowchart which shows the processing procedure of hand-off state determination. The flowchart which shows the process sequence of basic control amount correction | amendment calculation. The flowchart which shows the process sequence of the basic control amount correction | amendment calculation of another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus (EPS), 2 ... Steering, 6 ... Steering wheel, 10 ... EPS actuator, 11 ... ECU, 12 ... Motor, 14 ... Torque sensor, 15 ... Vehicle speed sensor, 16 ... Steering sensor, 21 ... Microcomputer , 25 ... current command value calculation unit, 27 ... basic assist control unit, 28 ... steering return control unit, 29 ... steering speed target value calculation unit, 34 ... adder, 35 ... steering correction calculation unit, θs ... steering angle, ωs: Steering speed, ω0: Threshold value, ωs *: Steering speed target value, Δωs: Steering speed deviation, α: Threshold value, Iq *: Current command value, Ias *: Basic assist control amount, Isb *: Steering return control amount, εsb, εsb ′: basic control amount, β: correction amount, τ: steering torque, τ1, τ2: threshold, K: correction gain.

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 is calculated by executing feedback control based on a deviation between the steering speed target value and the actual steering speed. A device,
The control means reduces a compensation component for executing the steering return control when the steering operation state shifts from a steered state to a released state;
An electric power steering device. The electric power steering apparatus according to claim 1, wherein
The electric power steering apparatus according to claim 1, wherein the reduction of the compensation component is continued until the steering speed target value and the actual steering speed are initially equal. In the electric power steering device according to claim 1 or 2,
The electric power steering apparatus according to claim 1, wherein the suppression of the compensation component is performed from a point in time when the steering operation state is in a steered state.

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