JP2008265605A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device in which the vibration of a steering system generated when a reverse input stress is applied thereto is effectively suppressed. <P>SOLUTION: A microcomputer extracts a frequency component corresponding to the vibration of the steering system generated when the reverse input stress is applied to a steering wheel from a pinion angle as the signal indicating the state of the steering system, and calculates a power spectrum Sp as its effective value (step 201). When the power spectrum Sp is equal to or higher than a predetermined threshold Sth (Sp ≥ Sth, step 203: YES), the control of the steering system of the microcomputer is changed to a regenerative brake control for braking the rotation of the motor (motor rotation braking control, step 204). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus.

  Conventionally, a power steering apparatus for a vehicle includes an electric power steering apparatus (EPS) using a motor as a drive source. Such EPS has a high degree of freedom in layout as compared with a hydraulic power steering apparatus. It is characterized by low energy consumption. For this reason, in recent years, its adoption has been examined in a wide range of vehicle types from small vehicles to large vehicles.

Now, in such EPS, the vibration of the steering system becomes one of the factors that impair the steering feeling. That is, when the driver feels the vibration of the steering system or the noise generated by the vibration, the steering feeling is greatly impaired. For this reason, in EPS, various countermeasures in terms of structure and control have been conventionally taken in order to suppress such vibration of the steering system (see, for example, Patent Document 1 and Patent Document 2).
JP 2006-27537 A JP 2006-335228 A

  However, the vibrations that occur in the steering system are not limited to those that are caused by the motor that is the drive source. That is, when reverse input stress is applied to the steered wheels when traveling on an irregular road surface, the reverse input stress remains in the steering system as vibration until the damping. Then, the vibration is transmitted from the steering system to the steering wheel, which may deteriorate the steering feeling.

  The configuration described in Patent Document 2 extracts a vibration frequency component from a motor control output (motor rotation angle or current value) and adds a vibration suppression control amount for canceling the vibration frequency component. . Therefore, in the EPS in which the motor and the steering system are connected, a certain degree of suppression effect can be expected for vibration generated in the steering system. However, the vibration component of the steering system extracted from the control output of the motor is still indirect, and a phase shift occurs in the compensation control based thereon. For this reason, the effect of the compensation control is also limited, and there has been a strong demand for the creation of an effective measure that can effectively suppress such vibration of the steering system.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric power steering apparatus capable of effectively suppressing vibration of a steering system caused by application of reverse input stress. There is.

  In order to solve the above problems, the invention according to claim 1 is directed to a steering force assisting device provided to apply an assist force for assisting a steering operation to a steering system using a motor as a drive source, and the steering An electric power steering apparatus comprising a control means for controlling the operation of the steering force assisting device based on a signal indicating a state of the system, based on application of reverse input stress from the signal indicating the state of the steering system. A specific frequency extraction unit capable of extracting a specific frequency component corresponding to the vibration generated in the steering system, and the control unit is configured such that the effective value of the extracted specific frequency component is equal to or greater than a predetermined threshold value; The gist is to execute control for restricting rotation of the motor.

  According to the above configuration, before the vibration caused by the application of the reverse input stress becomes obvious as the deterioration of the steering feeling, the occurrence of the vibration caused by the application of the reverse input stress is detected immediately and the suppression is promptly suppressed. be able to. And since it is the structure which suppresses the vibration which generate | occur | produces in a steering system by switching to the control which controls rotation of a motor, ie, restraining a steering system, the vibration suppression effect by a phase shift like the above-mentioned prior art is effective. There is no problem of degradation.

The gist of the invention described in claim 2 is that the control means executes control for restricting rotation of the motor only when the vehicle speed is in a predetermined speed range.
That is, the control for restricting the rotation of the motor is extremely effective for suppressing the vibration of the steering system, but it is not always preferable from the viewpoint of providing the assist force that is an original function of the EPS, and is based on the execution of the control. The restraint of the steering system may hinder the steering feeling. Therefore, attention is paid to the fact that the amplitude of vibration generated in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels and is amplified in a specific speed region where resonance occurs in the suspension. By executing the control for restricting the rotation of the motor only in the speed region where the vibration of the steering system is most noticeable as described above, it is effective while avoiding the deterioration of the steering feeling accompanying the control. In addition, vibration of the steering system can be suppressed.

  The gist of the invention described in claim 3 is that it comprises determination means for determining the presence or absence of a steering operation, and the control means does not execute control for restricting rotation of the motor during steering operation.

  That is, as described above, the control for restricting the motor rotation is not always preferable from the viewpoint of providing assist force, which is an essential function of EPS. However, as described above, when the steering operation is not performed, that is, only when the steering operation is not performed, steering is effectively performed while avoiding the deterioration of the steering feeling due to the control that restricts the rotation of the motor. The vibration of the system can be suppressed.

  The invention according to claim 4 is based on a steering force assisting device provided to give an assist force for assisting a steering operation to a steering system using a motor as a drive source, and a signal indicating a state of the steering system. An electric power steering apparatus comprising a control means for controlling the operation of the steering force assisting device, comprising a judging means for judging the presence or absence of a steering operation, wherein the control means has a predetermined vehicle speed during a non-steering operation. If it is in the speed range, the gist is to execute control for restricting the rotation of the motor.

  According to the above configuration, it is possible to effectively suppress the vibration of the steering system caused by the application of reverse input stress. And since extraction of a specific frequency component and calculation of the effective value are not performed, there exists an advantage that the calculation load is small.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power steering apparatus which can suppress effectively the vibration of the steering system which arises by application of reverse input stress can be provided.

Hereinafter, an embodiment in which the present invention is embodied in a column type electric power steering apparatus (EPS) will be described with reference to the drawings.
As shown in FIG. 1, in the electric power steering apparatus (EPS) 1 of the present embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation of the steering shaft 3 accompanying the operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. Specifically, the steering shaft 3 of the present embodiment is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10 via universal joints 7a and 7b, and the rack and pinion mechanism 4 includes: The pinion teeth 10a formed at one end of the pinion shaft 10 are engaged with the rack teeth 5a on the rack shaft 5 side. Then, the reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 11 connected to both ends of the rack shaft 5, so that the steering angle of the steered wheels 12 is increased. That is, the traveling direction of the vehicle is changed.

  The EPS 1 according to the present embodiment controls the operation of the EPS actuator 22 by providing an assist force for assisting the steering operation to the steering system by rotating the steering shaft 3 using the motor 21 as a drive source. ECU23 which performs.

  More specifically, the EPS actuator 22 of the present embodiment is configured as a so-called column-type EPS actuator that applies assist force to the column shaft 8, and the motor 21 that is a drive source is connected to the column shaft via the speed reduction mechanism 24. 8 is drive-coupled. In this embodiment, the speed reduction mechanism 24 is configured by meshing a reduction gear 25 provided so as not to rotate relative to the column shaft 8 and a motor gear 26 provided so as not to rotate relative to the motor shaft 21a. Has been. In the present embodiment, a so-called worm and wheel is employed for the speed reduction mechanism 24. The EPS actuator 22 as a steering force assisting device decelerates the rotation of the motor 21 that is a driving source by the speed reduction mechanism 24 and transmits it to the column shaft 8, thereby giving the motor torque as an assist force to the steering system. It has a configuration.

  On the other hand, the ECU 23 as control means supplies driving power to the motor 21 that is a driving source of the EPS actuator 22. And it is comprised so that rotation of the motor 21, ie, the action | operation of the EPS actuator 22, may be controlled through the supply of the drive electric power.

  More specifically, the ECU 23 is connected to a torque sensor 31 provided on the column shaft 8. In this embodiment, the column shaft 8 is formed by connecting a first shaft 8 a on the steering 2 side and a second shaft 8 b on the intermediate shaft 9 (pinion shaft 10) side via a torsion bar 33. Yes. The torque sensor 31 includes a torsion bar 33 and a pair of angle sensors 34a and 34b (resolvers) provided at both ends of the torsion bar 33 (the end of the first shaft 8a and the end of the second shaft 8b). It is configured.

  That is, the torque sensor 31 of the present embodiment is configured as a twin resolver type torque sensor, and the ECU 23 detects the rotation angle (steering angle θs) of the first shaft 8a by the first angle sensor 34a. The rotation angle (pinion angle θp) of the second shaft 8b is detected by the second angle sensor 34b. Then, the steering torque τ is detected based on the difference between the rotation angles detected by the both angle sensors 34a and 34b, that is, the twist angle of the torsion bar 33.

  In the present embodiment, the vehicle speed V detected by the vehicle speed sensor 35 is input to the ECU 23. Then, the ECU 23 determines a target assist force to be applied to the steering system based on the vehicle state quantities detected by these sensors, and drives the motor 21 to generate the target assist force in the EPS actuator 22. Execute power supply.

Next, an aspect of assist control in the EPS of the present embodiment will be described.
As shown in FIG. 2, the ECU 23 includes a microcomputer 41 that outputs a motor control signal, and a drive circuit 42 that supplies drive power to the motor 21 that is a drive source of the EPS actuator 22 based on the motor control signal. Configured.

  In the present embodiment, the ECU 23 is connected with a current sensor 43 for detecting the actual current value I supplied to the motor 21 and a rotation angle sensor 44 (see FIG. 1) for detecting the motor rotation angle θm. ing. Then, the microcomputer 41 controls the drive circuit 42 based on each vehicle state quantity and the actual current value I of the motor 21 and the motor rotation angle θm detected based on the output signals of the current sensor 43 and the rotation angle sensor 44. A motor control signal to be output is generated.

  More specifically, the microcomputer 41 is calculated by a current command value calculation unit 45 that calculates a target value of assist force to be applied to the steering system, that is, a current command value Iq * corresponding to the target assist force, and a current command value calculation unit 45. And a motor control signal output unit 46 for outputting a motor control signal based on the current command value Iq *.

  In the present embodiment, the steering torque τ detected by the torque sensor 31, the steering torque τ detected by the vehicle speed sensor 35, and the vehicle speed V are input to the current command value calculation unit 45. The current command value calculation unit 45 calculates a current command value Iq * based on the steering torque τ and the vehicle speed V. Specifically, the current command value calculation unit 45 calculates a current command value Iq * corresponding to a larger target assist force as the steering torque τ increases and the vehicle speed V decreases.

  The current command value Iq * output from the current command value calculation unit 45 is output to the motor control signal output unit 46 together with the actual current value I detected by the current sensor 43 and the motor rotation angle θm detected by the rotation angle sensor 44. Entered. The motor control signal output unit 46 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, a brushless motor that rotates by supplying three-phase (U, V, W) driving power is used as the motor 21. Then, the motor control signal output unit 46 converts the phase current values (Iu, Iv, Iw) of the motor 21 detected as the actual current value I into d, q axis current values in the d / q coordinate system (d / q The current feedback control is performed by performing conversion.

  That is, the current command value Iq * is input to the motor control signal output unit 46 as a q-axis current command value, and the motor control signal output unit 46 outputs the phase current based on the motor rotation angle θm detected by the rotation angle sensor 44. The value (Iu, Iv, Iw) is d / q converted. Further, the motor control signal output unit 46 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.

  Here, the drive circuit 42 according to the present embodiment is a known PWM inverter in which a pair of switching elements (FETs) connected in series is a basic unit (arm) and three arms corresponding to each phase are connected in parallel. The motor control signal output from the microcomputer 41 defines the on-duty ratio of each FET constituting the drive circuit 42. That is, a motor control signal is applied to the gate terminal of each FET constituting the drive circuit 42, and each FET is turned on / off in response to the motor control signal, thereby driving three phases (U, V, W). Electric power is supplied to the motor 21. As a result, the operation of the motor 21, that is, the operation of the EPS actuator 22 is controlled.

(Suppression control of vibration caused by reverse input stress)
Next, suppression control of vibration caused by reverse input stress in the present embodiment will be described.
As shown in FIG. 2, in the present embodiment, the microcomputer 41 constituting the ECU 23 is provided with a specific frequency extraction unit 51 as specific frequency extraction means capable of extracting a specific frequency component from an input signal. . In the present embodiment, a pinion angle θp indicating the rotation angle of the pinion shaft 10 constituting the steering system is input to the specific frequency extraction unit 51 as a signal indicating the state of the steering system. The specific frequency extraction unit 51 extracts a specific frequency component corresponding to the vibration of the steering system caused by the application of reverse input stress to the steered wheels 12 from the input pinion angle θp. And the specific frequency extraction part 51 of this embodiment is comprised so that the effective value of the said extracted specific frequency component may be output as a power spectrum Sp.

  Specifically, as shown in the flowchart of FIG. 3, the specific frequency extraction unit 51 first performs a bandpass filter process on the input pinion angle θp (step 101) to apply the reverse input stress. A frequency component of 14 to 16 Hz is extracted as a specific frequency component corresponding to the vibration of the steering system caused (step 102). Next, the specific frequency extraction unit 51 obtains an effective value of the frequency component extracted in step 102 by RMS (Root Means square) calculation (step 103). Then, low-pass filter processing is executed (step 104), and the value after the low-pass filter processing is output as a power spectrum Sp (step 105).

  In this embodiment, the power spectrum Sp output from the specific frequency extraction unit 51 is input to the switching determination unit 52, and the switching determination unit 52 receives the input power spectrum Sp, that is, the reverse input. It is determined whether or not the effective value of the specific frequency component corresponding to the vibration of the steering system resulting from the application of stress is greater than or equal to a predetermined threshold value. When the power spectrum Sp is equal to or greater than a predetermined threshold, the switching determination unit 52 restricts (restrains) the rotation of the motor 21 with respect to the motor control signal output unit 46. A switching signal Sc indicating that switching should be performed is output.

  That is, when the effective value of the extracted specific frequency component is equal to or greater than a predetermined threshold, the microcomputer 41 of the present embodiment controls the motor control to control the rotation of the motor 21, specifically, Then, the regenerative brake control is performed so that all the FETs on the upper stage side (power supply side) or the lower stage side (ground side) in the drive circuit 42 are set to “ON”. Then, by restraining the steering shaft 3 connected to the motor 21 by this regenerative brake control, it is configured to suppress vibrations generated in the steering system.

  That is, as shown in the flowchart of FIG. 4, when the microcomputer 41 obtains each state quantity used for motor control (step 201), it first executes the specific frequency extraction calculation as described above to apply reverse input stress. The power spectrum Sp is calculated as the effective value of the specific frequency component corresponding to the vibration of the steering system caused by the (step 202). Then, it is determined whether or not the power spectrum Sp is greater than or equal to a predetermined threshold value Sth (step 203). If the power spectrum Sp is greater than or equal to the predetermined threshold value Sth (Sp ≧ Sth, step 203: YES), The motor control is switched to regenerative brake control that restricts the rotation of the motor 21 (motor rotation restriction control, step 204).

  If it is determined in step 203 that the power spectrum Sp is less than the predetermined threshold value Sth (Sp <Sth, step 203: NO), normal motor control for applying assist force to the steering system is performed. Execute (normal control, step 205).

As described above, according to the present embodiment, the following operations and effects can be obtained.
The microcomputer extracts the frequency component corresponding to the vibration of the steering system caused by the application of reverse input stress to the steered wheel from the pinion angle as a signal indicating the state of the steering system, and calculates the power spectrum Sp as its effective value (Step 201). When the power spectrum Sp is equal to or greater than a predetermined threshold value Sth (Sp ≧ Sth, step 203: YES), the motor control is switched to regenerative brake control that restricts the rotation of the motor (motor rotation restriction control, Step 204).

  According to the above configuration, before the vibration caused by the application of the reverse input stress becomes obvious as the deterioration of the steering feeling, the occurrence of the vibration caused by the application of the reverse input stress is detected immediately and the suppression is promptly suppressed. be able to. And since it is the structure which aims at suppression of the vibration which arises in a steering system by switching to the regenerative brake control which controls rotation of the motor 21, and restraining the steering shaft 3 connected with the said motor 21, the above-mentioned prior art Thus, there is no problem of a reduction in vibration suppression effect due to a phase shift as seen in FIG.

In addition, you may change this embodiment as follows.
In the present embodiment, the present invention is embodied in a so-called column type EPS 1, but applied to a so-called rack type that applies assist force to the rack shaft 5, or a so-called pinion type EPS that applies assist force to the pinion shaft 10. May be.

  In the present embodiment, the pinion angle θp indicating the rotation angle of the pinion shaft 10 constituting the steering system is used as the signal indicating the state of the steering system. The steering angle θs (steering wheel angle) or the steering torque τ detected by the torque sensor 31 may be used. Needless to say, the position of the pinion angle θp, the steering angle θs, and the steering torque τ in the frequency analysis is not an instantaneous value but a continuous signal.

In the present embodiment, the regenerative brake control is executed as the motor rotation restriction control. However, it is also possible to perform lock control in which the energized phase is fixed and electrically locked.
In the present embodiment, when the power spectrum Sp that is the effective value of the specific frequency component corresponding to the vibration of the steering system is equal to or greater than the predetermined threshold value Sth, the motor control is controlled to restrict the rotation of the motor 21. (See FIG. 4). However, the present invention is not limited to this, and switching to such motor rotation restriction control may be performed only when the vehicle speed V is in a predetermined speed range (V1 ≦ V ≦ V2).

  Specifically, as shown in the flowchart of FIG. 5, when it is determined that the power spectrum Sp is equal to or greater than a predetermined threshold Sth (Sp ≧ Sth, Step 303: YES), the vehicle speed V is subsequently set to a predetermined speed. It is determined whether it is in the region (V1 ≦ V ≦ V2) (step 304). When the vehicle speed V is in the speed range (step 301: YES), motor rotation restriction control is executed (step 305). In the flowchart of FIG. 5, steps 301 to 303 and steps 305 and 306 are the same as steps 201 to 203 and steps 204 and 205 in the flowchart of FIG. 4, respectively. For this reason, the description is omitted for convenience of description.

  That is, although the motor rotation restriction control is extremely effective for suppressing vibration of the steering system, it is not always preferable from the viewpoint of providing assist force, which is an essential function of the EPS. The restraint may hinder the steering feeling. Therefore, attention is paid to the fact that the amplitude of vibration generated in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels 12 and is amplified in a specific speed region (V1 ≦ V ≦ V2) where resonance occurs in the suspension. To do. As described above, the motor rotation restriction control is executed only in the speed region where the vibration of the steering system is most prominent, so that the steering feeling can be effectively avoided while avoiding the deterioration of the steering feeling associated with the control. The vibration of the system can be suppressed.

  In addition, the steering state determination is executed to determine whether or not the driver performs a steering operation. And when it determines with there being steering operation, ie, at the time of steering operation, it is good also as a structure which does not perform the said motor rotation control control.

  Specifically, as shown in the flowchart of FIG. 6, when it is determined that the power spectrum Sp is equal to or greater than a predetermined threshold Sth (Sp ≧ Sth, Step 403: YES), the steering state determination is subsequently executed. (Step 404), it is determined whether or not there is a steering operation by the driver (Step 405). When there is no steering operation (step 404: NO), that is, the motor rotation restriction control is executed only during non-steering operation (step 406), and when there is a steering operation (step 404: YES), the motor rotation restriction is performed. Control is not executed, that is, normal control is executed (step 407).

  That is, as described above, the motor rotation restriction control is not necessarily preferable from the viewpoint of providing assist force, which is an essential function of EPS. However, as described above, when the steering operation is not performed, that is, only when the steering operation is not performed, the steering feeling is effectively prevented while avoiding the deterioration of the steering feeling due to the motor rotation restriction control. Can be suppressed.

  In the flowchart of FIG. 6, steps 401 to 403 and steps 406 and 407 are the same as steps 201 to 203 and steps 204 and 205 in the flowchart of FIG. For this reason, the description is omitted for convenience of description.

  Further, any method may be used for determining the steering state in step 404. For example, as shown in the flowchart of FIG. 7, each of the steering angle θs, the steering speed ωs, the steering torque τ, the yaw rate γ, etc. The presence or absence of a steering operation may be determined by comparing the value (absolute value) of the state quantity with a predetermined threshold value corresponding to each state quantity (steps 501 to 504).

  That is, whether the absolute value of the steering angle θs is equal to or smaller than the predetermined threshold θ0 (step 501), whether the absolute value of the steering speed ωs is equal to or smaller than the predetermined threshold ω0 (step 502), or whether the absolute value of the steering torque τ is predetermined. Whether the absolute value of the yaw rate γ is equal to or smaller than a predetermined threshold γ0 (step 504). If all of these state quantities are equal to or less than the corresponding threshold values (| θs | ≦ θ0, | ωs | ≦ ω0, | τ | ≦ τ0, and | γ | ≦ γ0, that is, steps 501 to 501 In step 504: all YES, it is determined that the steering operation is not performed (step 505). When at least one of the input state quantities exceeds the corresponding threshold (| θs |> θ0, | ωs |> ω0, | τ |> τ0, or | γ |> γ0, step 501 -Step 504: Either is NO), it is preferable to determine that there is a steering operation (step 506), and so on.

  Furthermore, as shown in the flowchart of FIG. 8, the condition determination regarding the vehicle speed V (step 604) and the condition determination regarding the steering state (steps 605 and 606) may be used in combination. As a result, it is possible to more effectively avoid the steering feeling caused by the motor rotation restriction control and effectively suppress the vibration of the steering system.

  In this embodiment, the power spectrum Sp, which is the effective value of the frequency component corresponding to the vibration of the steering system caused by the application of reverse input stress, is calculated, and when the power spectrum Sp is greater than or equal to a predetermined threshold, the motor rotation It was decided to execute regulatory control. However, the present invention is not limited to this, and when the vehicle speed V is in the predetermined speed region (V1 ≦ V ≦ V2) during non-steering operation without calculating the power spectrum Sp and comparing it with the threshold value, It is good also as composition which performs motor rotation regulation control.

  That is, as shown in the flowchart of FIG. 9, after each state quantity is acquired (step 701), first, the steering state determination as described above is executed (step 702, see FIG. 7), and there is a steering operation by the driver. Whether or not (step 703). If there is no steering operation (step 703: NO), it is subsequently determined whether or not the vehicle speed V is in a predetermined speed range (V1 ≦ V ≦ V2) (step 704). If it is in the speed region (step 704: YES), motor rotation restriction control is executed (step 705).

  If it is determined in step 703 that there is a steering operation (step 703: YES), or if it is determined in step 704 that the vehicle speed V is not in the predetermined speed range (step 704: NO), The motor rotation restriction control is not performed, and normal control may be used (step 706). Even with such a configuration, it is possible to suppress the vibration of the steering system caused by the application of reverse input stress. And since extraction of a specific frequency component and calculation of the effective value are not performed, there exists an advantage that the calculation load is small.

The schematic block diagram of an electric power steering device (EPS). The control block diagram of EPS of this embodiment. The flowchart which shows the process sequence of specific frequency extraction. The flowchart which shows the aspect of vibration suppression control. The flowchart which shows the aspect of vibration suppression control of another example. The flowchart which shows the aspect of vibration suppression control of another example. The flowchart which shows the process sequence of steering state determination. The flowchart which shows the aspect of vibration suppression control of another example. The flowchart which shows the aspect of vibration suppression control of another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 2 ... Steering, 3 ... Steering shaft, 8 ... Column shaft, 9 ... Intermediate shaft, 10 ... Pinion shaft, 12 ... Steering wheel, 21 ... Motor, 22 ... EPS actuator, 23 DESCRIPTION OF SYMBOLS ... ECU, 31 ... Torque sensor, 35 ... Vehicle speed sensor, 41 ... Microcomputer, 42 ... Drive circuit, 45 ... Current command value calculation part, 46 ... Motor control signal output part, 51 ... Specific frequency extraction part, 52 ... Switching determination part , Θp ... pinion angle, Sp ... power spectrum, Sth ... threshold, τ ... steering torque, τ0 ... threshold, θs ... steering angle, θ0 ... threshold, γ ... yaw rate, γ0 ... threshold, ωs ... steering angle, ω0 ... threshold, V: vehicle speed, Sc: switching signal.

Claims (4)

A steering force assisting device provided to apply an assist force for assisting a steering operation to the steering system using a motor as a drive source, and the operation of the steering force assisting device is controlled based on a signal indicating the state of the steering system. An electric power steering device comprising control means for
A specific frequency extracting means capable of extracting a specific frequency component corresponding to vibration generated in the steering system based on application of reverse input stress from a signal indicating the state of the steering system;
The control means, when the effective value of the extracted specific frequency component is greater than or equal to a predetermined threshold, executing control to restrict the rotation of the motor;
An electric power steering device. In the electric power steering apparatus according to claim 1,
The electric power steering apparatus, wherein the control means executes control for restricting rotation of the motor only when the vehicle speed is in a predetermined speed range. In the electric power steering device according to claim 1 or 2,
A determination means for determining the presence or absence of a steering operation;
The electric power steering apparatus characterized in that the control means does not execute control for restricting rotation of the motor during a steering operation. A steering force assisting device provided to apply an assist force for assisting a steering operation to the steering system using a motor as a drive source, and the operation of the steering force assisting device is controlled based on a signal indicating the state of the steering system. An electric power steering device comprising control means for
A determination means for determining the presence or absence of a steering operation;
The control means executes control for restricting rotation of the motor when the vehicle speed is in a predetermined speed region during non-steering operation;
An electric power steering device.

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