JP2004338562A - Electric power steering controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering controller that reduces steering torque comparing with manual steering even when abnormality occurs in a torque sensor, can facilitate steering, and has no unnatural steering feeling. <P>SOLUTION: A CPU 21 (central processing unit) of the electric power steering controller determines abnormality of the torque sensor and discriminates steering direction based on the steering angle θ. The CPU 21, based on the discrimination result of the steering direction and the steering angle θ, provides a hysteresis characteristic from the discrimination result, and calculates an assist current command value I* based on the steering angle θ. When the torque sensor is abnormal, the CPU 21 controls an electric motor 6 based on the assistant current command value I* based on the steering angle θ instead of the assist current command value based on the steering torque. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric power steering control device for applying an assisting force by an electric motor to a steering system of an automobile or a vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electric power steering control device of an automobile or a vehicle detects a steering torque generated on a steering shaft by operating a steering wheel (handle) with a torque sensor, and determines a control target value of the electric motor based on the steering torque. A current command value, that is, an assist control amount is calculated. Then, in a current feedback control system of the control device, a difference between a current command value, which is a control target value, and a value of a current (current value) actually flowing through the electric motor is obtained as a control value. It controls the motor to assist the steering force of the steering wheel. This control is called assist control.
[0003]
In the conventional control device, when it is determined that the torque sensor is abnormal, the assist control is stopped, and manual steering is performed in a state where there is no assist. For example, a conventional technique that does not perform the assist control in this way is disclosed in Japanese Patent Application Laid-Open Publication No. H11-163873.
[0004]
However, if it is determined that the torque sensor is abnormal and the current supply to the electric motor is immediately stopped, the steering force of the steering wheel becomes heavy, and the steering feeling is reduced as compared with the state where the normal assist control is performed. (Steering feeling) is degraded. Then, in order to solve this problem, the technique of Patent Document 2 has been proposed.
[0005]
According to the disclosed technology, when there is an abnormality in the torque sensor, the steering angle of the steering wheel is detected by the steering angle sensor, and a target current value to be supplied to the electric motor is calculated in accordance with the steering angle. The electric motor is controlled based on a current value.
[0006]
Here, the outline of the electric power steering control device will be briefly described.
FIG. 8 is a diagram showing control blocks of a general conventional electric power steering control device. Note that, in the figure, a control block surrounded by a dotted line shows a configuration in which an ECU (electronic control device) constituting the control device functions according to an assist control program, and does not show a hardware configuration. Reference numeral 100 denotes a vehicle model, and the vehicle model 100 has a reaction force characteristic of a steering angle θ and a total reaction force Tt shown in FIG. Note that this reaction force characteristic is equivalent to that of a handle shaft. That is, in the vehicle model 100, when the steering wheel is operated at the steering angle θ, the total reaction force Tt shown in FIG.
[0007]
When the driver operates the steering wheel while receiving assistance from the assist torque Ta described later, the difference between the total reaction force Tt and the assist torque Ta is detected by the torque sensor 4 as the steering torque Th.
[0008]
When the torque sensor 4 detects the steering torque Th, the assist command generation unit 300 in the ECU refers to the assist map and refers to the assist map to the assist current command value I *, which is the target current value corresponding to the steering torque Th. And supplies the assist current command value I * to the current control unit 400. When current controller 400 outputs assist current I to motor 500 based on assist current command value I *, motor 500 is driven to rotate and outputs motor torque Tm. This motor torque Tm is transmitted to a handle shaft (not shown) via a speed reducer 600 connected to the motor 500, and becomes an assist torque Ta to assist steering.
[0009]
The relationship between the steering angle θ and the steering torque Th when this assist control is being executed is shown in the steering angle-steering torque characteristic denoted by reference numeral 700.
When the torque sensor 4 of the electric power steering control device having the above-described configuration becomes abnormal and the assist control is stopped, the relationship between the steering angle θ and the steering torque Th in the case where the manual operation is performed is denoted by the reference numeral 800. This is shown in the calculated steering angle-steering torque characteristic (manual steering characteristic).
[0010]
As described above, there is a hysteresis related to the steering direction between the steering torque Th and the steering angle θ (for example, see the reaction force characteristic of the vehicle model 100 in FIG. 8).
[0011]
[Patent Document 1]
JP-A-6-92244 [Patent Document 2]
JP 2001-106099 A
[Problems to be solved by the invention]
In the technique of Patent Document 2, this hysteresis is not considered at all, and when the torque sensor is abnormal, a target current value to be supplied to the electric motor is calculated according to the steering angle, and based on the target current value. The electric motor is controlled. Therefore, if the target current value for the assist control is simply set based on the steering angle, there is a problem that an unnatural steering feeling, specifically, a steering feeling with a strong spring feeling is obtained.
[0013]
The present invention has been made to solve the above problems, and its purpose is to reduce the steering torque as compared with manual steering even when the torque sensor is abnormal, thereby facilitating the steering, Another object of the present invention is to provide an electric power steering control device that does not have an unnatural steering feeling.
[0014]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 generates a motor control amount based on the steering torque detected by the steering torque detecting means, and outputs an assist force based on the motor control amount. In the electric power steering control device that controls the motor as described above, abnormality determination means for determining abnormality of the torque detection means, steering angle detection means for detecting a steering angle of a steering wheel, and a steering direction based on the steering angle. A steering direction discriminating means for discriminating; a motor control amount calculating means for calculating a motor control amount based on the steering angle by giving a hysteresis characteristic based on the discrimination result based on the discrimination result and the steering angle; However, when it is determined that the torque detection means is abnormal, instead of the motor control amount based on the steering torque, the motor control amount calculation means The electric power steering control apparatus characterized by comprising a control means for controlling the motor based on the motor control amount that issued it is an gist.
[0015]
According to a second aspect of the present invention, in the first aspect, there is provided a vehicle behavior detecting means for detecting a vehicle behavior, wherein the motor control amount calculating means changes a motor control amount based on the steering angle according to the vehicle behavior. It is characterized by the following.
[0016]
According to a third aspect of the present invention, in the second aspect, the vehicle behavior detecting means is a vehicle speed detecting means for detecting a vehicle speed.
According to a fourth aspect of the present invention, in the second aspect, the vehicle behavior detecting means is a lateral acceleration detecting means for detecting a lateral acceleration acting on the vehicle.
[0017]
According to a fifth aspect of the present invention, in the second aspect, the vehicle behavior detecting means is a yaw rate detecting means for detecting a yaw rate acting on the vehicle.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in an electric power steering control device mounted on an automobile (vehicle) will be described with reference to FIGS.
[0019]
FIG. 1 schematically shows an electric power steering control device.
A torsion bar 3 is provided on a handle shaft 2 connected to a steering wheel (hereinafter, referred to as a handle 1). The torque sensor 4 is mounted on the torsion bar 3. The sensor output is supplied to an ECU (electronic control device) 20. When the handle shaft 2 rotates and a force is applied to the torsion bar 3, the torsion bar 3 is twisted in accordance with the applied force, and the torsion bar 3, that is, the steering torque Th applied to the handle 1 is detected by the torque sensor 4. . The sensor output is supplied to the ECU 20 (electronic control device). Further, a steering angle sensor 17 is provided on the handle shaft 2 side of the torsion bar 3 in order to detect the steering angle θ of the steering wheel 1. The steering angle θ including the operation direction is detected by the steering angle sensor 17 and is output to the ECU 20 as a signal indicating the operation state of the steering wheel 1.
[0020]
The torque sensor 4 corresponds to steering torque detecting means, and the steering angle sensor 17 corresponds to steering angle detecting means.
Further, a speed reducer 5 is provided on the handle shaft 2. The speed reducer 5 includes a gear 7 attached to a rotating shaft of an electric motor (hereinafter, referred to as a motor) 6, and a gear meshed with the gear 7 and fixed to the handle shaft 2. A pinion shaft 8 is fixed to the output side of the speed reducer 5. A pinion 9 is fixed to the tip of the pinion shaft 8, and the pinion 9 meshes with a rack 10. The rack 10 and the pinion 9 constitute a rack & pinion mechanism 11. A tie rod 12 is fixed to both ends of the rack 10, and a knuckle 13 is rotatably connected to a tip end of the tie rod 12. A front wheel 14 as a tire is fixed to the knuckle 13. One end of the knuckle 13 is rotatably connected to the cross member 15.
[0021]
A steering mechanism is constituted by the handle shaft 2, the torsion bar 3, the speed reducer 5, the electric motor 6, the gear 7, the pinion shaft 8, the pinion 9, the rack 10, the rack & pinion mechanism 11, the tie rod 12, and the like.
[0022]
Therefore, when the electric motor 6 rotates, the rotation speed is reduced by the speed reducer 5 and transmitted to the rack 10. The rack 10 can change the direction of the front wheels 14 provided on the knuckle 13 via the tie rods 12 to change the traveling direction of the vehicle. The front wheel 14 is provided with a vehicle speed sensor 16, and the sensor output is supplied to the ECU 20.
[0023]
The vehicle speed sensor 16 corresponds to vehicle speed detecting means and vehicle behavior detecting means.
(Electrical configuration)
Next, the electric configuration of the electric power steering control device is shown in FIG.
[0024]
The torque sensor 4 outputs a signal indicating the steering torque Th of the steering wheel 1. The steering angle sensor 17 outputs a signal indicating the steering angle θ of the steering wheel 1. The vehicle speed sensor 16 outputs a detection signal indicating the vehicle speed V at that time and corresponding to the rotation speed of the front wheels 14.
[0025]
As shown in FIG. 2, the ECU 20 is electrically connected to a motor drive current sensor 18 for detecting a drive current (motor current Im, corresponding to the motor current value) flowing through the electric motor 6. A signal indicating the motor current Im (motor current value) is supplied from the current sensor 18.
[0026]
The ECU 20 includes a CPU 21 (central processing unit) as control means, a ROM 22, and a RAM 23. Various control programs executed by the CPU 21 are stored in the ROM 22. The RAM 23 temporarily stores the result of the arithmetic processing when the CPU 21 performs the arithmetic processing.
[0027]
The CPU 21 receives detection signals from the various sensors and performs processing of various control programs such as assist control. Then, the CPU 21 calculates a current value (control value) based on the detection signals, further performs a PWM calculation based on the control value, outputs the result to the drive circuit 24, and outputs the result to the drive circuit 24. The drive of the electric motor 6 is controlled via the.
[0028]
FIG. 2 is a functional block diagram of the CPU 21. In this embodiment, the inside of the CPU 21 indicates functions executed by a program. For example, the phase compensator 30 is not independent hardware but shows a phase compensation function executed inside the CPU 21. In the following description of the functions inside the CPU 21, various parameters such as "vehicle speed V" and "steering torque Th" are used as meanings of corresponding signals for convenience of description.
[0029]
Here, an outline of the assist control (first assist control) executed by the CPU 21 when the torque sensor 4 is normal will be described.
The steering torque Th detected by the torque sensor 4 is phase-compensated by the phase compensator 30 in order to enhance the stability of the electric power steering control device, and the phase-compensated steering torque Th is input to the current command value calculation unit 31. You. The vehicle speed V detected by the vehicle speed sensor 16 is also input to the current command value calculator 31. The current command value calculator 31 calculates an assist current command value I * corresponding to the vehicle speed V and the steering torque Th based on an assist map (hereinafter, referred to as a first assist map) stored in the ROM 22 in advance. The current command value I * is supplied to the current control unit 36.
[0030]
The current control unit 36 calculates a PI control value or a PID control value based on a signal corresponding to a difference from an actual motor current (motor drive current) Im detected by the motor drive current sensor 18 and calculates the control value. Is output to the PWM operation unit 37. The PWM operation unit 37 performs a PWM operation according to the control value, and supplies the operation result to the drive circuit 24.
[0031]
As a result, by controlling the drive of the electric motor 6 via the drive circuit 24, an appropriate assist force by the electric motor 6 can be obtained.
Next, assist control (second assist control) executed by the CPU 21 when the torque sensor 4 is abnormal will be described. FIG. 3 is a functional block diagram of the CPU 21 when the second assist control is performed, and the inside of the CPU 21 shows functions executed by a program. In the following description of the functions inside the CPU 21, various parameters such as “vehicle speed V” and “steering angle θ” are used as meanings of corresponding signals for convenience of description.
[0032]
In the second assist control, the steering angle θ detected by the steering angle sensor 17 is input to the current command value calculator 42 and the differentiator 40 of the CPU 21. The differentiator 40 calculates the steering angular velocity by differentiating the steering angle θ with time, and inputs the steering angular velocity to the steering direction determination unit 41. The steering direction determination unit 41 determines the steering direction based on the steering angular velocity, and inputs the determination result to the current command value calculation unit 42. Specifically, the steering direction is determined based on the sign (positive or negative) of the deviation between the steering angle θ input in the previous control cycle and the steering angle θ input in the current control cycle. The vehicle speed V detected by the vehicle speed sensor 16 is input to the current command value calculation unit 42.
[0033]
The current command value calculation unit 42 selects a map from an assist map (hereinafter, referred to as a second assist map) stored in the ROM 22 in advance according to the result of the determination of the steering direction. That is, the second assist map includes a map a in which the steering direction is a positive direction and a map b in which the steering direction is a negative direction. When the steering direction is the positive direction, the map a is selected and the steering direction is selected. Is negative, map b is selected.
[0034]
Then, an assist current command value I * corresponding to the steering angle θ and the vehicle speed V is calculated based on the selected maps a and b. In the present embodiment, turning the steering wheel 1 rightward is defined as a positive direction, and turning leftward is defined as a negative direction.
[0035]
The assist current command value I * corresponds to a motor control amount based on the steering angle θ.
Each map is a three-dimensional map. As shown in FIG. 3, when the horizontal axis is the steering angle θ and the vertical axis is the assist current command value I *, the assist current command value I * corresponding to the vehicle speed V is calculated. Is set to In the map b in the negative direction, the steering angle-assist current command value curve is shifted to the right as compared with the map a in the positive direction.
[0036]
Here, the map a in the forward direction will be described. As described above, since the map b in the negative direction is shifted rightward by a predetermined amount (shift amount Δ), the description is omitted. The shift amount Δ corresponds to the assist current command value calculated based on the steering torque Th based on the first assist map and the steering torque Th based on the second assist map when the vehicle speed V is the same. It is set in advance by a test or the like so that the assist current command value calculated at the steering angle θ to be made matches or substantially matches.
[0037]
In the forward direction map a, when the steering angle θ is located to the right of the neutral position 0 (straight forward steering position) during forward steering, the steering angle θ increases (in FIG. ), The assist current command value I * increases, the electric motor 6 rotates forward, and the motor torque Tm in the forward rotation direction increases. At this time, the assist current command value I * is set to be larger when the vehicle speed V is higher than when the vehicle speed V is lower.
[0038]
The forward direction map a indicates that the steering angle θ decreases when the steering angle θ is located to the left of the neutral position 0 (straight forward steering position) during forward steering (in FIG. 3, the leftward direction of the horizontal axis). , The assist current command value I * decreases, the electric motor 6 rotates in the reverse direction, and the motor torque Tm in the reverse rotation direction increases. At this time, the assist current command value I * is set to be smaller when the vehicle speed V is higher than when the vehicle speed V is lower. As described above, according to the result of the determination of the steering direction by the steering direction determination unit 41, the current command value calculation unit 42 calculates the assist current command value I * with the hysteresis characteristic, and calculates the calculated assist current command value I *. * Is input to the current control unit 36.
[0039]
The current control unit 36 calculates a PI control value or a PID control value based on a signal corresponding to a difference from an actual motor current (motor drive current) Im detected by the motor drive current sensor 18 and calculates the control value. Is output to the PWM operation unit 37. The PWM operation unit 37 performs a PWM operation according to the control value, and supplies the operation result to the drive circuit 24. As a result, the CPU 21 performs current control and controls the drive of the electric motor 6 via the drive circuit 24, so that the assisting force of the electric motor 6 can be obtained.
[0040]
(Operation of the embodiment)
Next, the operation of the present embodiment will be described with reference to FIGS.
FIG. 4 is a flowchart of the assist control program, and the CPU 21 executes this program by interruption at a predetermined cycle every several ms.
[0041]
In S10, it is determined whether or not the torque sensor 4 is abnormal. The determination as to whether or not the torque sensor 4 is abnormal is made based on whether or not a detection signal is input from the torque sensor 4 (disconnection detection) and whether or not the detection signal exceeds a predetermined threshold. If it is determined that the torque sensor 4 is not abnormal, a normal operation is performed in S70, and the program is temporarily terminated.
[0042]
In the normal operation of S70, the first assist control is executed, that is, the assist current command value I * is determined based on the steering torque Th detected by the torque sensor 4 and the vehicle speed V using the first assist map described above. Then, the electric motor 6 is driven and controlled based on the assist current command value I *.
[0043]
If it is determined in S10 that the torque sensor 4 is abnormal, the steering angle θ is detected in S20, and in S30, the steering angle θ is differentiated with respect to time to determine the steering direction (the differentiator 40, the steering direction determination unit 41). Function of). Subsequently, in S40, a map a or a map b according to the result of the steering direction determination is selected from the second assist maps. That is, the map a is selected for forward steering, and the map b is selected for negative steering. In S50, an assist current command value I * depending on the steering angle θ and the vehicle speed V is calculated based on the selected map a or map b. In S60, the drive of the electric motor 6 is controlled based on the assist current command value I *, and the program is temporarily terminated.
[0044]
The CPU 21 corresponds to abnormality determination means (S10), steering direction determination means (S30), motor control amount calculation means (S50), and control means (S60).
FIG. 5 is a schematic diagram showing a control block in the case where the torque sensor 4 of the electric power steering control device of the present embodiment is abnormal and the second assist control is performed based on the steering angle θ detected by the steering angle sensor 17. It is.
[0045]
The vehicle model 100 of the vehicle equipped with the electric power steering control device of the present embodiment has a reaction force characteristic of the steering angle θ and the total reaction force Tt as shown in FIG. 5, as in the vehicle model described in FIG. Shall be provided.
[0046]
When the driver operates the steering wheel when the assist of the assist torque Ta is received when the torque sensor 4 is abnormal, the ECU 20 inputs the steering angle θ and the vehicle speed V, and the ECU 20 inputs the steering angle θ and the vehicle speed V based on the steering angle θ and the vehicle speed V. The assist current command value I * is obtained from the map a or the map b corresponding to the steering direction among the two assist maps. Then, based on the assist current command value I *, the ECU 20 controls the driving of the electric motor 6 to obtain the motor torque Tm. The motor torque Tm is transmitted to the handle shaft 2 via the speed reducer 5 connected to the electric motor 6, and becomes the assist torque Ta to assist the steering. At this time, in the vehicle model 100, when the steering wheel is operated, the total reaction force Tt according to the steering angle θ is applied, but the difference between the total reaction force Tt and the assist torque Ta is the steering torque Th required for steering. .
[0047]
In FIG. 5, a diagram indicated by a reference numeral 900 indicates a steering angle-steering torque characteristic obtained when the torque sensor 4 is abnormal in the present embodiment. In FIG. 5, a diagram denoted by reference numeral 1000 shows the reaction force characteristics of the total reaction force Tt and the steering angle θ when the vehicle speed V changes in the vehicle model.
[0048]
According to the above embodiment, the following effects can be obtained.
(1) The CPU 21 of the electric power steering control device according to the present embodiment determines abnormality of the torque sensor 4 (torque detecting means) as abnormality determining means, and determines the steering direction based on the steering angle as steering direction determining means. I decided to judge. Then, the CPU 21 calculates the motor control amount based on the steering angle θ based on the determination result of the steering direction and the steering angle θ based on the determination result of the steering direction and the steering angle θ based on the determination result. Further, when the torque sensor 4 is abnormal, the CPU 21 controls the assist current command value I * (motor control value) based on the steering angle θ instead of the assist current command value (motor control amount) based on the steering torque Th when the torque sensor 4 is abnormal. The electric motor 6 is controlled based on the control amount.
[0049]
As a result, the electric motor 6 is driven by the assist current command value I * having the hysteresis characteristic according to the steering direction, and the assist torque can be output. Therefore, even if the torque sensor 4 becomes abnormal, an unnatural steering feeling does not occur depending on the steering direction, and a natural steering feeling can be obtained.
[0050]
(2) In the present embodiment, the vehicle speed sensor 16 includes a vehicle behavior detecting unit and a vehicle speed detecting unit, and the CPU 21 changes the assist current command value I * (motor control amount) based on the steering angle θ according to the vehicle speed V. I did it.
[0051]
As a result, a necessary assist torque Ta can be output according to the vehicle speed V.
In addition, this embodiment may be changed as follows.
[0052]
(1) In the above embodiment, the vehicle speed sensor 16 is used as the vehicle behavior detecting means. However, as shown in FIG. 6, a lateral acceleration sensor 50 may be used. In this case, hysteresis also exists in the case of the lateral acceleration acting on the vehicle.
[0053]
That is, in the reaction force characteristic indicated by reference numeral 1000 in FIG. 4, the steering angle θ, the total reaction force Tt, and the amount of inclination of the characteristic line are different depending on whether the vehicle speed V is high or low. On the other hand, as for the lateral acceleration G, as the lateral acceleration G increases, the steering angle θ, the total reaction force Tt, and the amount of inclination of the characteristic line increase. In FIG. 4, the characteristic diagram denoted by reference numeral 1000 is substituted for convenience of explanation.
[0054]
Therefore, the maps a and b used by the current command value calculation unit 42 use a three-dimensional map including the steering angle θ, the lateral acceleration G, and the assist current command value I *. This three-dimensional map is set in advance based on a test or the like, and is stored in the ROM 22 in advance. The lateral acceleration sensor 50 corresponds to a vehicle behavior detecting unit and a lateral acceleration detecting unit.
[0055]
(2) In the above embodiment, the vehicle speed sensor 16 is used as the vehicle behavior detecting means in the above embodiment, but a yaw rate sensor 60 may be used as shown in FIG. In this case, hysteresis also exists in the case of the lateral acceleration acting on the vehicle.
[0056]
That is, in the reaction force characteristic indicated by reference numeral 1000 in FIG. 4, the steering angle θ, the total reaction force Tt, and the amount of inclination of the characteristic line are different depending on whether the vehicle speed V is high or low. On the other hand, also in the yaw rate Y, as the yaw rate Y increases, the steering angle θ, the total reaction force Tt, and the amount of inclination of the characteristic line increase. In FIG. 4, the characteristic diagram denoted by reference numeral 1000 is substituted for convenience of explanation.
[0057]
Therefore, the maps a and b used by the current command value calculation unit 42 use a three-dimensional map including the steering angle θ, the yaw rate Y, and the assist current command value I *. This three-dimensional map is set in advance based on a test or the like, and is stored in the ROM 22 in advance. The yaw rate sensor 60 corresponds to vehicle behavior detecting means and yaw rate detecting means.
[0058]
(3) In the above embodiment, the vehicle speed-responsive assist control is performed according to the steering torque Th and the vehicle speed V. However, the assist control may be performed only according to the steering torque Th.
[0059]
【The invention's effect】
As described in detail above, according to the first to fifth aspects of the present invention, even when the torque sensor is abnormal, the steering torque can be reduced as compared with manual steering, and steering can be facilitated. The effect is that there is no unnatural steering feeling.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an electric power steering control device according to an embodiment of the present invention.
FIG. 2 is a functional block diagram of the CPU 21 when the torque sensor is normal.
FIG. 3 is a functional block diagram of a CPU 21 when the torque sensor is abnormal.
FIG. 4 is a flowchart of an assist control program.
FIG. 5 is a control block diagram when assist control is performed when the torque sensor is abnormal.
FIG. 6 is a view corresponding to FIG. 3 of another embodiment.
FIG. 7 is a view corresponding to FIG. 3 of another embodiment.
FIG. 8 is a control block diagram of a conventional electric power steering control device.
[Explanation of symbols]
1. Steering wheel (handle)
4: Torque sensor (steering torque detecting means)
16 Vehicle speed sensor (vehicle behavior detecting means, vehicle speed detecting means)
17. Steering angle sensor (steering angle detecting means)
21 CPU (abnormality determining means, steering direction determining means, motor control amount calculating means, control means)
50: lateral acceleration sensor (vehicle behavior detecting means, lateral acceleration detecting means)
60 ... Yaw rate sensor (vehicle behavior detecting means, yaw rate detecting means)
θ: steering angle G: lateral acceleration V: vehicle speed Th: steering torque

Claims (5)

An electric power steering control device that generates a motor control amount based on the steering torque detected by the steering torque detection unit and controls the motor to output an assist force based on the motor control amount,
Abnormality determination means for determining abnormality of the torque detection means;
Steering angle detection means for detecting a steering angle of the steering wheel;
Steering direction determining means for determining a steering direction based on the steering angle,
A motor control amount calculating unit that calculates a motor control amount based on the steering angle by giving a hysteresis characteristic based on the determination result based on the determination result and the steering angle;
When the abnormality determination unit determines that the torque detection unit is abnormal, the abnormality determination unit controls the motor based on the motor control amount calculated by the motor control amount calculation unit instead of the motor control amount based on the steering torque. An electric power steering control device comprising control means. A vehicle behavior detecting means for detecting a vehicle behavior,
2. The electric power steering control device according to claim 1, wherein the motor control amount calculation unit changes a motor control amount based on the steering angle according to the vehicle behavior. The electric power steering control device according to claim 2, wherein the vehicle behavior detecting means is a vehicle speed detecting means for detecting a vehicle speed. The electric power steering control device according to claim 2, wherein the vehicle behavior detecting means is a lateral acceleration detecting means for detecting a lateral acceleration acting on the vehicle. The electric power steering control device according to claim 2, wherein the vehicle behavior detecting means is a yaw rate detecting means for detecting a yaw rate acting on the vehicle.

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