JP6609465B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus.

2. Description of the Related Art In recent years, in electric power steering devices, a technique has been proposed that makes it possible to apply assist force by an electric motor even when steering torque cannot be detected by detection means (torque sensor) that detects steering torque. Has been.
For example, in the electric power steering apparatus described in Patent Document 1, when a failure occurs in the torque sensor, the target current value of the motor is set as follows based on the steering angle θ and the steering angular velocity ω that is a differential value thereof. To do. When θ> 0 and ω ≧ 0, a constant current value I (V) determined by the vehicle speed is set as the current target value in order to assist the steering operation in the right direction. When θ <0 and ω ≦ 0, −I (V) is set as a current target value in order to assist the steering operation in the left direction. On the other hand, when θ> 0 and ω <0, or θ <0 and ω> 0, the steering wheel is in the return state, so the current target value is set to zero to stop the steering assist.

JP 2003-72580 A

  An object of the present invention is to provide an electric power steering device that can rotate a steering wheel at an ideal steering speed of a driver even when a failure occurs in a torque detection means.

For this purpose, the present invention provides an electric motor for applying an assisting force to steering a steering wheel of a vehicle, torque detecting means for detecting a steering torque of the steering wheel, and a steering angle that is a rotation angle of the steering wheel. Based on the detected steering angle detecting means and the torque detected by the torque detecting means when the torque detecting means is normal, detected by the steering angle detecting means when the torque detecting means is not normal and a control means for controlling the driving force of the electric motor based on a deviation of the actual steering angular velocity and the steering angle and the target steering angular velocity of the control means, the torque detecting means on the basis of the steering angle When a failure occurs, a basic target current at failure is set to set a basic target current at failure that is the basis of the target current supplied to the electric motor. Setting means; deviation current setting means for setting a deviation current according to a deviation between the target steering angular velocity and the actual steering angular velocity; and the failure basic target current set by the failure basic target current setting means; An electric power steering apparatus comprising: target current determining means for determining the target current when a failure occurs in the torque detecting means based on the deviation current set by the deviation current setting means. is there.

  According to the present invention, even when a failure occurs in the torque detection means, the steering wheel can be rotated at the ideal steering speed of the driver.

It is a figure showing the schematic structure of the electric power steering device concerning an embodiment. It is a schematic block diagram of a control apparatus. It is a schematic block diagram of a target current calculation part. It is the schematic of the control map which shows a response | compatibility with steering torque, vehicle speed, and base current. It is a schematic block diagram of a control part. It is a schematic block diagram of the current determination part at the time of a sensor failure. It is a schematic block diagram of the temporary sensor failure electric current determination part. It is a schematic block diagram of the base current calculation part at the time of a sensor failure. It is the schematic of the control map which shows a response | compatibility with the steering angle after absolute value conversion, and the base current at the time of temporary sensor failure. It is the schematic of the control map which shows a response | compatibility with a vehicle speed correction coefficient and a vehicle speed. It is a schematic block diagram of a return correction coefficient setting part. It is the schematic of the control map which shows a response | compatibility with the steering angle after absolute value conversion, and a temporary return correction coefficient. It is the schematic of the control map which shows a response | compatibility with a motor rotational speed and a rotational speed correction coefficient. It is the schematic of the control map which shows a response | compatibility with a vehicle speed and a vehicle speed correction coefficient. It is a schematic block diagram of a steering angular velocity deviation electric current determination part. (A) is the schematic of the control map which shows a response | compatibility with a calculation steering angle and a vehicle speed, and a target steering angular velocity when the steering wheel is cut. (B) is a schematic diagram of a control map showing the correspondence between the calculated steering angle and the vehicle speed and the target steering angular speed when the steering wheel is turned back. It is a control map which shows a response | compatibility with a steering angular velocity deviation and a steering angular velocity deviation electric current.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an electric power steering apparatus 100 according to an embodiment.
Electric power steering device 100 (hereinafter, also simply referred to as “steering device 100”) is a steering device for arbitrarily changing the traveling direction of a vehicle, and in this embodiment, an automobile as an example of the vehicle. 1 illustrates the configuration applied to 1.

  The steering device 100 includes a wheel-like steering wheel 101 that is operated by a driver to change the traveling direction of the automobile 1, and a steering shaft 102 that is provided integrally with the steering wheel 101. Yes. The steering device 100 includes an upper connecting shaft 103 connected to the steering shaft 102 via a universal joint 103a, and a lower connecting shaft 108 connected to the upper connecting shaft 103 via a universal joint 103b. . The lower connecting shaft 108 rotates in conjunction with the rotation of the steering wheel 101.

  Steering device 100 includes tie rods 104 connected to left and right front wheels 150 as rolling wheels, and rack shaft 105 connected to tie rods 104. Further, the steering device 100 includes a pinion 106 a that constitutes a rack and pinion mechanism together with rack teeth 105 a formed on the rack shaft 105. The pinion 106 a is formed at the lower end portion of the pinion shaft 106. The rack shaft 105, the pinion shaft 106, and the like function as a transmission mechanism that transmits the rotational operation force of the steering wheel 101 as the rolling force of the front wheel 150. The pinion shaft 106 applies a driving force (rack axial force) for rolling the front wheel 150 by rotating to the rack shaft 105 for rolling the front wheel 150.

  The steering device 100 also has a steering gear box 107 that houses the pinion shaft 106. The pinion shaft 106 is connected to the lower connection shaft 108 via a torsion bar 112 in the steering gear box 107. The steering gear box 107 includes a steering torque T applied to the steering wheel 101 based on the relative rotational angle between the lower connecting shaft 108 and the pinion shaft 106, in other words, based on the twist amount of the torsion bar 112. A torque sensor 109 is provided as an example of torque detecting means for detecting the torque.

  Further, the steering device 100 includes an electric motor 110 supported by the steering gear box 107 and a speed reduction mechanism 111 that reduces the driving force of the electric motor 110 and transmits it to the pinion shaft 106. The speed reduction mechanism 111 includes, for example, a worm wheel (not shown) fixed to the pinion shaft 106, a worm gear (not shown) fixed to the output shaft of the electric motor 110, and the like. The electric motor 110 applies a driving force (rack axial force) for rolling the front wheel 150 to the rack shaft 105 by applying a rotational driving force to the pinion shaft 106. The electric motor 110 according to the present embodiment is a three-phase brushless motor having a resolver 120 that outputs a rotation angle signal θms linked to a motor rotation angle θm that is the rotation angle of the electric motor 110.

  The steering device 100 includes a control device 10 as an example of a control unit that controls the operation of the electric motor 110. An output signal from the torque sensor 109 described above is input to the control device 10. In addition, the control device 10 detects a vehicle speed Vc that is a moving speed of the vehicle 1 via a network (CAN) that performs communication for sending signals for controlling various devices mounted on the vehicle 1. An output signal v from the unit 170 or the like is input. The vehicle speed detection unit 170 may be a vehicle speed sensor itself.

  The steering device 100 configured as described above drives the electric motor 110 based on the steering torque T detected by the torque sensor 109, and transmits the driving force (generated torque) of the electric motor 110 to the pinion shaft 106. Thereby, the torque generated by the electric motor 110 assists the driver's steering force applied to the steering wheel 101.

Next, the control device 10 will be described.
FIG. 2 is a schematic configuration diagram of the control device 10.
The control device 10 is an arithmetic and logic circuit composed of a CPU, ROM, RAM, backup RAM, and the like.
The control device 10 includes a torque signal Td obtained by converting the steering torque T detected by the torque sensor 109 described above into an output signal, a vehicle speed signal v corresponding to the vehicle speed Vc from the vehicle speed detection unit 170, and rotation from the resolver 120. An angle signal θms or the like is input.

  Then, the control device 10 calculates (sets) a target current It necessary for the electric motor 110 to supply based on the torque signal Td, the output signal v from the vehicle speed detection unit 170, and the like. And a control unit 30 that performs feedback control or the like based on the target current It calculated by the target current calculation unit 20. Further, the control device 10 calculates the motor rotation speed Vm based on the motor rotation angle calculation unit 71 that calculates the motor rotation angle θm of the electric motor 110 and the motor rotation angle θm calculated by the motor rotation angle calculation unit 71. And a motor rotation speed calculation unit 72 for calculating. Further, the control device 10 includes a steering angle calculation unit 73 that calculates a steering angle θs that is a rotation angle of the steering wheel 101.

[Target current calculation unit]
FIG. 3 is a schematic configuration diagram of the target current calculation unit 20.
The target current calculation unit 20 calculates a base current calculation unit 21 that calculates a base current Ib that serves as a reference for setting the target current It, and inertia compensation that calculates an inertia compensation current Is for canceling the inertia moment of the electric motor 110. A current calculation unit 22 and a damper compensation current calculation unit 23 that calculates a damper compensation current Id that limits the rotation of the motor are provided. Further, the target current calculation unit 20 determines a temporary target current Itf that is a temporary target current based on the values calculated by the base current calculation unit 21, the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23. A temporary target current determination unit 25 is provided. In addition, the target current calculation unit 20 includes a phase compensation unit 26 that compensates for the phase of the steering torque T detected by the torque sensor 109.

The target current calculation unit 20 includes a sensor failure detection unit 27 that detects a failure of the torque sensor 109, and a target current It that is supplied to the electric motor 110 when the sensor failure detection unit 27 detects a failure of the torque sensor 109. And a sensor failure current determination unit 28 for calculating a base current. The target current calculation unit 20 includes a final target current determination unit 29 that determines a target current It that is finally supplied to the electric motor 110.
The target current calculation unit 20 includes a torque signal Td, an output signal from the vehicle speed detection unit 170 corresponding to the vehicle speed Vc, a motor rotation speed signal Vms from the motor rotation speed calculation unit 72 corresponding to the motor rotation speed Vm, and the like. Entered.

FIG. 4 is a schematic diagram of a control map showing the correspondence between the steering torque T, the vehicle speed Vc, and the base current Ib.
Based on the torque signal Ts obtained by phase compensation of the torque signal Td by the phase compensation unit 26 and the output signal from the vehicle speed detection unit 170, the base current calculation unit 21 calculates the base current Ib from the control map illustrated in FIG. calculate.
The inertia compensation current calculation unit 22 calculates the inertia compensation current Is based on the torque signal Ts obtained by phase compensation of the torque signal Td by the phase compensation unit 26 and the output signal from the vehicle speed detection unit 170.
The damper compensation current calculation unit 23 is based on the torque signal Ts obtained by phase compensation of the torque signal Td by the phase compensation unit 26, the output signal from the vehicle speed detection unit 170, the output signal from the motor rotation speed calculation unit 72, and the like. A compensation current Id is calculated.

  The temporary target current determination unit 25 includes a base current Ib calculated by the base current calculation unit 21, an inertia compensation current Is calculated by the inertia compensation current calculation unit 22, and a damper calculated by the damper compensation current calculation unit 23. A temporary target current Itf is determined based on the compensation current Id. For example, the temporary target current determination unit 25 determines the current obtained by adding the inertia compensation current Is to the base current Ib and subtracting the damper compensation current Id as the temporary target current Itf.

The sensor failure detection unit 27 detects, for example, an abnormality such that the output from the torque sensor 109 is fixed at 0 (V) or a voltage other than 0 to 5 (V) is output. Is determined to have failed, and the failure is output to the final target current determination unit 29.
The sensor failure current determination unit 28 will be described in detail later.

  The final target current determination unit 29 determines the temporary target determined by the temporary target current determination unit 25 when the sensor failure detection unit 27 does not determine that there is a failure (when a signal indicating failure has not been acquired). The current Itf is determined as the final target current It. When the sensor failure detection unit 27 determines that a failure has occurred (when a signal indicating failure has been acquired), the final target current determination unit 29 determines the final target current It as the sensor failure current determination unit 28. The current is switched to the current Ie at the time of sensor failure determined in (1).

Here, a state in which the torsion bar 112 has a twist amount of 0 is defined as a neutral state (neutral position), and the steering wheel 101 (lower connection shaft 108) and the pinion shaft when the steering wheel 101 rotates clockwise from the neutral state (neutral position). The direction in which the relative rotation angle with respect to 106 changes (the direction in which the relative rotation angle occurs) is positive (the steering torque T is positive). Further, the direction in which the relative rotation angle between the steering wheel 101 (lower connection shaft 108) and the pinion shaft 106 changes when the steering wheel 101 rotates counterclockwise from the neutral state (the direction in which the relative rotation angle occurs) is minus (steering torque T Is minus).
When the steering torque T detected by the torque sensor 109 is positive, the base current calculation unit 21 calculates the base current Ib so as to rotate the electric motor 110 in the clockwise rotation direction, and the base current Ib The direction of flow is positive. That is, as shown in FIG. 4, when the steering torque T is positive, the base current calculation unit 21 calculates a positive base current Ib, and generates torque in a direction that rotates the electric motor 110 in the clockwise direction. When the steering torque T is negative, the base current calculation unit 21 calculates a negative base current Ib, and generates torque in a direction that rotates the electric motor 110 in the left rotation direction.
Further, when the steering wheel 101 rotates to the right from the state where the steering angle θs that is the rotation angle of the steering wheel 101 is 0 degree, the steering angle θs becomes positive, and when the steering wheel 101 rotates to the left, the steering angle θs becomes negative. It becomes.

(Control part)
FIG. 5 is a schematic configuration diagram of the control unit 30.
As shown in FIG. 5, the control unit 30 includes a motor drive control unit 31 that controls the operation of the electric motor 110, a motor drive unit 32 that drives the electric motor 110, and an actual current Im that actually flows through the electric motor 110. And a motor current detection unit 33 for detection.
The motor drive control unit 31 is based on a deviation between the target current It finally determined by the target current calculation unit 20 and the actual current Im supplied to the electric motor 110 detected by the motor current detection unit 33. A feedback (F / B) control unit 40 that performs feedback control, and a PWM signal generation unit 60 that generates a PWM (pulse width modulation) signal for PWM driving the electric motor 110.

  The feedback control unit 40 includes a deviation calculating unit 41 for obtaining a deviation between the target current It finally determined by the target current calculating unit 20 and the actual current Im detected by the motor current detecting unit 33, and the deviation is A feedback (F / B) processing unit 42 that performs feedback processing so as to be zero.

The feedback (F / B) processing unit 42 performs feedback control so that the target current It and the actual current Im match. For example, the feedback (F / B) processing unit 42 is proportional to the deviation calculated by the deviation calculating unit 41. Is proportionally processed, integrated by an integral element, and these values are added by an addition operation unit.
The PWM signal generation unit 60 generates a PWM signal for driving the electric motor 110 by PWM (pulse width modulation) based on the output value from the feedback control unit 40, and outputs the generated PWM signal.

The motor drive unit 32 is a so-called inverter, and includes, for example, six independent transistors (FETs) as switching elements. Three of the six transistors are a positive line of a power source, an electric coil of each phase, The other three transistors are connected to the electric coil of each phase and the negative side (ground) line of the power source. Then, the driving of the electric motor 110 is controlled by driving the gates of two transistors selected from the six and switching the transistors.
The motor current detection unit 33 detects the value of the actual current Im flowing through the electric motor 110 from the voltage generated at both ends of the shunt resistor connected to the motor drive unit 32.

The motor rotation angle calculation unit 71 (see FIG. 2) calculates the motor rotation angle θm based on the rotation angle signal θms from the resolver 120.
The motor rotation speed calculation unit 72 (see FIG. 2) calculates the motor rotation speed Vm of the electric motor 110 based on the motor rotation angle θm calculated by the motor rotation angle calculation unit 71.

  The steering angle calculation unit 73 (see FIG. 2) is configured such that the steering wheel 101, the speed reduction mechanism 111, and the like are mechanically coupled, so that the rotation angle (steering angle θs) of the steering wheel 101 and the motor rotation angle θm of the electric motor 110 are. The steering angle θs is calculated based on the motor rotation angle θm calculated by the motor rotation angle calculation unit 71. For example, the steering angle calculation unit 73 performs steering based on the integrated value of the difference between the previous value and the current value of the motor rotation angle θm calculated periodically (for example, every 1 millisecond) by the motor rotation angle calculation unit 71. The angle θs is calculated. The steering angle calculation unit 73 functions as an example of a steering angle detection unit that detects the steering angle θs.

<Sensor failure current determination unit>
FIG. 6 is a schematic configuration diagram of the sensor failure current determination unit 28.
The sensor failure current determination unit 28 is a temporary sensor failure current determination unit 281 that determines a temporary sensor failure current Ief, which is a temporary value of the sensor failure current Ie, and a deviation between the target steering angular velocity and the actual steering angular velocity. And a steering angular velocity deviation current determining unit 282 that determines a steering angular velocity deviation current Iv according to the above. Further, the sensor failure current determination unit 28 finally determines the temporary sensor failure current Ief determined by the temporary sensor failure current determination unit 281 and the steering angular velocity deviation current Iv determined by the steering angular velocity deviation current determination unit 282. Is provided with a final sensor failure current determining unit 283 for determining a sensor failure current Ie. In other words, the sensor failure current determination unit 28 determines the temporary sensor failure current Ief as an example of the failure basic target current that is the basis of the target current It supplied to the electric motor 110 when the torque sensor 109 fails. Is provided with a temporary sensor failure current determination unit 281 (an example of a failure basic target current setting means). The sensor failure current determination unit 28 includes a steering angular velocity deviation current determination unit 282 (an example of a deviation current setting unit) that sets a steering angular velocity deviation current Iv as an example of a deviation current. Further, the sensor failure current determination unit 28 includes a final sensor failure current determination unit 283 (an example of target current determination means) that determines a target current It when a failure occurs in the torque sensor 109.

(Current determination unit for temporary sensor failure)
FIG. 7 is a schematic configuration diagram of the temporary sensor failure current determination unit 281.
The temporary sensor failure current determination unit 281 sets an assigned steering angle θse, which is a steering angle to be substituted into a control map described later, based on the calculated steering angle θsc that is the steering angle θs calculated by the steering angle calculation unit 73. A substitution steering angle calculation unit 281a for calculating is provided.
Further, the temporary sensor failure current determination unit 281 calculates a sensor failure base current Ieb that is a base of the temporary sensor failure current Ief based on the substitution steering angle θse calculated by the substitution steering angle calculation unit 281a. A base current calculation unit 281b is provided.

Further, the temporary sensor failure current determining unit 281 sets a return correction coefficient setting unit Kr for correcting the temporary sensor failure current Ief to be small when the steering wheel 101 is switched back. 281c.
The temporary sensor failure current determination unit 281 returns by multiplying the sensor failure base current Ieb calculated by the sensor failure base current calculation unit 281b by the return correction coefficient Kr set by the return correction coefficient setting unit 281c. A return correction coefficient multiplication unit 281d that calculates the corrected base current Iebr is provided.

Further, the temporary sensor failure current determination unit 281 includes a rotation speed correction coefficient setting unit 281e that sets a rotation speed correction coefficient Km according to the motor rotation speed Vm.
Further, the temporary sensor failure current determination unit 281 multiplies the return-corrected base current Iebr calculated by the return correction coefficient multiplication unit 281d and the rotation speed correction coefficient Km set by the rotation speed correction coefficient setting unit 281e. Is provided with a rotational speed correction coefficient multiplier 281f for calculating the base current Iebv after rotational speed correction.

The temporary sensor failure current determination unit 281 includes a limit processing unit 281g that performs a limit process on the post-rotation speed corrected base current Iebv calculated by the rotation speed correction coefficient multiplication unit 281f.
Further, the temporary sensor failure current determination unit 281 performs an encoding process on the post-limit processing base current Il that is the post-rotation speed corrected base current Iebv after the limit processing by the limit processing unit 281g. It has.
Further, the temporary sensor failure current determination unit 281 includes a fade processing unit 281i that performs a fade process on the base current Il after the limit process that has been encoded by the encoding process unit 281h based on the vehicle speed Vc. Yes.

Next, elements constituting the temporary sensor failure current determination unit 281 will be described in detail.
The substitution steering angle calculation unit 281a integrates the difference between the previous value and the current value of the calculated steering angle θsc that is calculated periodically (for example, every 1 millisecond) by the steering angle calculation unit 73 from 0 degrees. The rotation angle from 0 degree is calculated, and this calculated value is set as the substitution steering angle θse. When a predetermined reset condition is satisfied, the substitution steering angle θse is reset to zero. The reset condition may be any condition that allows the user to grasp that the difference in the rotation angle (steering angle θs) of the steering wheel 101 has become 0 degrees. For example, the target current It set by the target current calculation unit 20 or A case where the actual current Im detected by the motor current detection unit 33 becomes close to 0 can be exemplified.

FIG. 8 is a schematic configuration diagram of the sensor failure base current calculation unit 281b.
The sensor failure base current calculation unit 281b includes an absolute value conversion unit 281ba that converts the substitution steering angle θse calculated by the substitution steering angle calculation unit 281a into an absolute value. Also, the sensor failure base current calculation unit 281b is a temporary sensor failure base current Ieb that is a temporary sensor failure base current Ieb based on the absolute value steering angle | θse | converted into an absolute value by the absolute value conversion unit 281ba. A temporary base current calculation unit 281bb for calculating the base current Ieba is provided. The sensor failure base current calculation unit 281b includes a vehicle speed correction coefficient setting unit 281bc that sets a vehicle speed correction coefficient Kv based on an output signal v from the vehicle speed detection unit 170 or the like. The sensor failure base current calculation unit 281b multiplies the temporary sensor failure base current Ieba calculated by the temporary base current calculation unit 281bb by the vehicle speed correction coefficient Kv set by the vehicle speed correction coefficient setting unit 281bc. Thus, a vehicle speed correction coefficient multiplying unit 281bd for calculating the sensor failure base current Ieb is provided. The sensor failure base current calculation unit 281b calculates the sensor failure base current Ieb periodically (for example, every 1 millisecond).

  The absolute value converting unit 281ba calculates the absolute value of the substitution steering angle θse having a plus or minus sign. The value calculated by the absolute value converting unit 281ba is the absolute steering angle | θse |.

FIG. 9 is a schematic diagram of a control map showing correspondence between the steering angle | θse | after absolute value conversion and the base current Ieba at the time of temporary sensor failure.
The temporary base current calculation unit 281bb is illustrated in FIG. 9 showing the correspondence between the steering angle | θse | after absolute value and the base current Ieba at the time of failure of the temporary sensor, which is created based on an empirical rule and stored in the ROM in advance. By substituting the steering angle | θse | after the absolute value into the control map, the base current Ieba at the time of temporary sensor failure is calculated.
In the control map shown in FIG. 9, when the absolute steering angle | θse | is equal to or smaller than a predetermined reference steering angle θse0, the temporary sensor failure base current Ieba is zero. When the absolute steering angle | θse | is larger than the reference steering angle θse0, the temporary sensor failure base current Ieba is set to gradually increase from 0 as the absolute steering angle | θse | increases. Has been.

FIG. 10 is a schematic diagram of a control map showing the correspondence between the vehicle speed correction coefficient Kv and the vehicle speed Vc.
The vehicle speed correction coefficient setting unit 281bc substitutes the vehicle speed Vc into the control map illustrated in FIG. 10 which shows the correspondence between the vehicle speed correction coefficient Kv and the vehicle speed Vc, which is created based on an empirical rule and stored in the ROM in advance. Thus, the vehicle speed correction coefficient Kv is calculated.
In the control map illustrated in FIG. 10, the vehicle speed correction coefficient Kv when the vehicle speed Vc is 0 (km / h) is 1, and the vehicle speed correction coefficient Kv when the vehicle speed Vc is 1 (km / h) is 0.1. Five. Further, the vehicle speed correction coefficient Kv when the vehicle speed Vc is 5 (km / h) is set to 0.3, and the vehicle speed correction coefficient Kv is gradually decreased while the vehicle speed Vc changes from 1 to 5 (km / h). ing. Further, the vehicle speed correction coefficient Kv when the vehicle speed Vc is 40 (km / h) is set to 0.4, and the vehicle speed correction coefficient Kv is gradually increased while the vehicle speed Vc changes from 5 to 40 (km / h). ing. The vehicle speed correction coefficient Kv is gradually decreased as the vehicle speed Vc increases from 40 (km / h). The above speed range is an example, and can be changed as appropriate according to vehicle characteristics.

  The vehicle speed correction coefficient multiplication unit 281bd multiplies the temporary sensor failure base current Ieba calculated by the temporary base current calculation unit 281bb by the vehicle speed correction coefficient Kv set by the vehicle speed correction coefficient setting unit 281bc, thereby causing a sensor failure. An hour base current Ieb is calculated (Ieb = Ieba × Kv), and the calculated sensor fault base current Ieb is output to the return correction coefficient multiplier 281d.

FIG. 11 is a schematic configuration diagram of the return correction coefficient setting unit 281c.
The return correction coefficient setting unit 281c includes an absolute value converting unit 281ca that converts the calculated steering angle θsc calculated by the steering angle calculating unit 73 into an absolute value, and an absolute value converted into an absolute value by the absolute value converting unit 281ca. A provisional return correction coefficient calculation unit 281cb that calculates a provisional return correction coefficient Kra, which is a provisional return correction coefficient Kr, based on the rear steering angle | θsc |. The return correction coefficient setting unit 281c includes a first selection unit 281cc that selects the temporary return correction coefficient Kra calculated by the temporary return correction coefficient calculation unit 281cb or a predetermined value according to the vehicle speed Vc. . Further, the return correction coefficient setting unit 281c calculates the calculated steering angle velocity calculated by time differentiation of the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the substituted steering angle θse calculated by the substituted steering angle calculation unit 281a. And a determination unit 281cd that determines whether the steering wheel 101 is cut back or not based on the sign (indicating the steering rotation direction). The determination by the determination unit 281cd may be performed based on the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the rotation direction signal of the motor rotation speed signal Vms from the motor rotation speed calculation unit 72. Further, the return correction coefficient setting unit 281c includes a second selection unit 281ce that selects a value selected by the first selection unit 281cc or a predetermined value according to the steering situation determined by the determination unit 281cd. .

  The absolute value converting unit 281ca calculates the absolute value of the calculated steering angle θsc having a plus or minus sign. The value calculated by the absolute value converting unit 281ca is the steering angle | θsc | after the absolute value conversion.

FIG. 12 is a schematic diagram of a control map showing a correspondence between the steering angle | θsc | after absolute value conversion and the provisional return correction coefficient Kra.
The provisional return correction coefficient calculation unit 281cb is illustrated in FIG. 12 illustrating the correspondence between the absolute value steering angle | θsc | and the provisional return correction coefficient Kra, which is created based on an empirical rule and stored in the ROM in advance. The temporary return correction coefficient Kra is calculated by substituting the steering angle | θsc | after absolute value into the control map.
In the control map shown in FIG. 12, when the absolute steering angle | θsc | is equal to or smaller than the predetermined lower steering angle θd, the provisional return correction coefficient Kra is 0, and the absolute steering angle is obtained. When | θsc | is equal to or greater than a predetermined upper steering angle θu, the provisional return correction coefficient Kra is 1. The provisional return correction coefficient Kra increases from 0 to 1 when the absolute steering angle | θsc | is between the lower steering angle θd and the upper steering angle θu.

  The first selection unit 281cc selects the temporary return correction coefficient Kra calculated by the temporary return correction coefficient calculation unit 281cb when the vehicle speed Vc is equal to or higher than a predetermined vehicle speed Vcd, and when the vehicle speed Vc is less than the predetermined vehicle speed Vcd. Selects 1 which is a predetermined value. The predetermined vehicle speed Vcd can be exemplified as 1 km / h.

  The determination unit 281cd multiplies the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the calculated steering angular velocity θsev calculated by time differentiation of the substitution steering angle θse calculated by the substitution steering angle calculation unit 281a. If the multiplication value obtained by this (= θsc × θsev) is greater than 0 (θsc × θsev> 0), it is determined that the cut is made, and if the multiplication value is less than 0 (θsc × θsev <0) It is determined that it has been switched back. As the multiplication value (= θsc × θsev), the motor rotation speed signal Vms (motor rotation speed Vm) from the motor rotation speed calculation unit 72 may be used instead of the calculated steering angular speed θsev.

  The second selection unit 281ce selects 1 which is a predetermined value when it is determined that the determination unit 281cd is cut, and the second selection unit 281ce is first when the determination unit 281cd is switched back. The temporary return correction coefficient Kra or 1 selected by the 1 selection unit 281cc is selected. Then, the second selection unit 281ce outputs the selected value as a return correction coefficient Kr.

  With the configuration described above, the return correction coefficient setting unit 281c sets the return correction coefficient Kr periodically (for example, every 1 millisecond). Then, the return correction coefficient setting unit 281c sets the return correction coefficient Kr to 1 when the steering wheel 101 is cut. Further, even when the steering wheel 101 is turned back, the return correction coefficient setting unit 281c sets the return correction coefficient Kr to 1 when the vehicle speed Vc is less than the predetermined vehicle speed Vcd. Further, the return correction coefficient setting unit 281c is configured such that the steering angle | θsc | after the absolute value is greater than or equal to the upper steering angle θu when the steering wheel 101 is turned back and the vehicle speed Vc is equal to or higher than the predetermined vehicle speed Vcd. In some cases, the return correction coefficient Kr is set to 1. On the other hand, when the steering wheel 101 is turned back and the vehicle speed Vc is equal to or higher than the predetermined vehicle speed Vcd, the return correction coefficient setting unit 281c has the absolute value steering angle | θsc | less than the upper steering angle θu. In some cases, a return correction coefficient Kr is set in accordance with the steering angle | θsc |

The rotation speed correction coefficient setting unit 281e sets a rotation speed correction coefficient Km corresponding to the motor rotation speed Vm.
FIG. 13 is a schematic diagram of a control map showing the correspondence between the motor rotation speed Vm and the rotation speed correction coefficient Km.
The rotational speed correction coefficient setting unit 281e is added to the control map illustrated in FIG. 13 which shows the correspondence between the motor rotational speed Vm and the rotational speed correction coefficient Km, which is previously created based on empirical rules and stored in the ROM. The rotational speed correction coefficient Km is calculated by substituting the rotational speed Vm.
In the control map shown in FIG. 13, when the motor rotation speed Vm is equal to or less than a predetermined rotation speed Vm0, the rotation speed correction coefficient Km is 1, and when the motor rotation speed Vm is greater than the rotation speed Vm0. The rotational speed correction coefficient Km is a value that gradually decreases from 1 to 0 as the motor rotational speed Vm increases.

FIG. 14 is a schematic diagram of a control map showing the correspondence between the vehicle speed Vc and the vehicle speed correction coefficient Kc.
The rotation speed correction coefficient setting unit 281e corrects the motor rotation speed Vm to be substituted into the control map shown in FIG. 13 using the vehicle speed correction coefficient Kc set based on the control map and the vehicle speed Vc shown in FIG. (Motor rotation speed Vm to be substituted into the control map shown in FIG. 13 = motor rotation speed Vm × Kc calculated by the motor rotation speed calculator 72).
In the control map illustrated in FIG. 14, the vehicle speed correction coefficient Kc when the vehicle speed Vc is from 0 to the first vehicle speed V1 is 1, and the vehicle speed correction coefficient Kc is 0 when the vehicle speed Vc is greater than the second vehicle speed V2. Three. Further, while the vehicle speed Vc increases from the first vehicle speed V1 to the second vehicle speed V2, the vehicle speed correction coefficient Kc is set to a value that gradually decreases from 1 to 0.3. It can be exemplified that the first vehicle speed V1 is 15 (km / h) and the second vehicle speed V2 is 35 (km / h). The predetermined value can be appropriately set according to vehicle characteristics.

  With the configuration described above, the rotation speed correction coefficient setting unit 281e sets the rotation speed correction coefficient Km periodically (for example, every 1 millisecond). Then, the rotational speed correction coefficient setting unit 281e sets the rotational speed correction coefficient Km to a value smaller than 1 to suppress excessive cutting when the motor rotational speed Vm is high, in other words, when the steering angular speed of the steering wheel 101 is high. Set to. However, in order to secure the assist force necessary for avoiding danger when the vehicle speed Vc is high, when the vehicle speed Vc is higher than the second vehicle speed V2, the motor rotation speed Vm substituted into the control map shown in FIG. 13 is small. Correct so that On the other hand, when the vehicle speed Vc is smaller than the first vehicle speed V1, no correction is made to reduce the motor rotation speed Vm that is substituted into the control map shown in FIG. 13 in order to prevent steering.

  The limit processing unit 281g outputs the upper limit value as the post-limit processing base current Il when the rotation-speed-corrected base current Iebv calculated by the rotation-speed correction coefficient multiplication unit 281f is larger than a predetermined upper-limit value. To do. On the other hand, when the calculated rotation speed corrected base current Iebv is equal to or lower than the upper limit value, the limit processing unit 281g outputs the calculated rotation speed corrected base current Iebv as the limit processed base current Il.

  When the sign of the substitution steering angle θse calculated by the substitution steering angle calculation unit 281a is positive, the encoding processing unit 281h adds a plus sign to the post-limit processing base current Il output from the limit processing unit 281g. Attached. On the other hand, when the sign of the substitution steering angle θse calculated by the substitution steering angle calculation unit 281a is negative, the encoding processing unit 281h is negative to the post-limit processing base current Il output from the limit processing unit 281g. A sign is attached.

  The return correction coefficient multiplication unit 281d, the rotation speed correction coefficient multiplication unit 281f, the limit processing unit 281g, and the encoding processing unit 281h described above perform each process periodically (for example, every 1 millisecond). Therefore, the encoding processing unit 281h outputs the rotational speed corrected base current Iebv to which the code is attached to the fade processing unit 281i periodically (for example, every 1 millisecond).

When the sensor failure detection unit 27 detects a failure of the torque sensor 109 in processing periodically (for example, every 1 millisecond), the fade processing unit 281i determines the value determined based on the vehicle speed Vc when the sensor failure occurs. When the current Ie is determined and a failure of the torque sensor 109 is not detected, the sensor failure current Ie is determined to be zero.
Then, when the sensor failure detection unit 27 detects a failure of the torque sensor 109 and determines the sensor failure current Ie based on the vehicle speed Vc, the fade processing unit 281i controls the vehicle speed Vc as illustrated in FIG. As shown in the map, when the vehicle speed correction coefficient Kv is a magnitude other than 0 to 1 (km / h) where the vehicle speed correction coefficient Kv changes greatly (speed greater than 1 (km / h)), the sensor failure current Ie is determined as the base current Iebv after rotation speed correction, which is provided with a code by the encoding processing unit 281h. On the other hand, when the vehicle speed Vc is 1 (km / h) or less, it takes a predetermined period from the current Ie at the time of the sensor failure to the base current Iebv after the rotational speed correction, which is indicated by the current encoding processing unit 281h. Gradually change. For example, when the vehicle speed Vc is decelerating from 1 (km / h), the base after rotation speed correction, in which the current encoding processing unit 281h is attached with the sign from the previous sensor failure current Ie in one second. A value that changes to the current Iebv is determined as a sensor failure current Ie periodically (for example, every 1 millisecond). On the other hand, when the vehicle speed Vc is accelerating from 0, in 0.5 seconds, the current Ie at the time of sensor failure is changed from the current Ie at the time of the sensor failure to the base current Iebv after the rotation speed correction that is signed by the current encoding processing unit 281h. The changing value is determined as the sensor failure current Ie periodically (for example, every 1 millisecond).

According to the steering device 100 configured as described above, normal assist control is performed using the target current It determined based on the steering torque T detected by the torque sensor 109 when the torque sensor 109 has failed as an assist current. Even when it cannot be performed, the assist control at the time of failure can be performed based on the output value from the resolver 120.
When performing the assist control at the time of failure, the vehicle speed correction coefficient Kv is set to 1 on the basis of the control map illustrated in FIG. 10 when the vehicle has a large frictional force on the road surface, so that the vehicle speed Vc is larger than 0. Increases assist power. As a result, even in the case of assist control at the time of failure, handling characteristics at the time of parking and stopping are ensured. On the other hand, when the vehicle speed Vc exceeds 1 (km / h) and moves to the dynamic friction force region, the vehicle speed correction coefficient Kv is set to 0.5 or less based on the control map illustrated in FIG. Since the power is weakened suddenly, it is adjusted so as not to over-assist. Further, in a region where the vehicle is turning and the vehicle speed Vc is greater than 10 (km / h), the steering force tends to increase. At this speed, the vehicle speed correction coefficient Kv is less than around 5 (km / h). Since it can be increased, the assist power increases. However, in the region where the vehicle speed Vc is greater than 40 (km / h), the vehicle speed correction coefficient Kv is set small, so that the assist force is weakened. Thereby, the wobbling of the vehicle at a high vehicle speed is suppressed.
Furthermore, even if the vehicle speed correction coefficient Kv changes greatly between 0 and 1 (km / h), the assist force is gradually changed by the fade processing unit 281i, so that the assist force changes abruptly. It is suppressed that steering feeling deteriorates due to the above.

  Further, at the time of switching back in the assist control at the time of failure, excessive cutting when the steering angular speed of the steering wheel 101 is large is suppressed by the rotational speed correction coefficient Km set by the rotational speed correction coefficient setting unit 281e. However, when the vehicle speed Vc is higher than the second vehicle speed V2, the rotational speed correction coefficient Km is set so as to increase, so that the assist force necessary to avoid danger when the vehicle speed Vc is high is ensured. Further, when the vehicle speed Vc is lower than the first vehicle speed V1, the rotational speed correction coefficient Km is set to be small, so that steering is suppressed even during low-μ road low speed traveling. Further, the steering catch when the vehicle is stopped is suppressed.

  As described above, according to the steering device 100 according to the present embodiment, it is possible to apply the assist force according to the use state of the vehicle even during the assist control at the time of failure. That is, it is possible to realize the provision of assist force for avoiding danger and also to provide assist force for general travel. As a result, even after a failure occurs in the torque sensor 109, it is possible to go to the home or the nearest dealer, and the safety of the driver can be ensured.

  In the embodiment described above, the fade processing unit 281i fades the sensor failure current Ie output from the sensor failure current determination unit 28 in accordance with the vehicle speed Vc, but the fade processing unit 281i also fades at other parts. Also good. For example, the post-rotation speed corrected base current Iebv input to the limit processing unit 281g may be faded before the limit processing unit 281g. As a result, the steering feeling is prevented from deteriorating due to the abrupt change of the assist force.

(Steering angular velocity deviation current determination unit)
FIG. 15 is a schematic configuration diagram of the steering angular velocity deviation current determining unit 282.
The steering angular velocity deviation current determination unit 282 is an actual steering angular velocity calculation unit 282a that calculates an actual steering angular velocity Vsa that is an actual steering angular velocity Vs, and a cut that determines whether the steering wheel 101 is cut or not. A return determination unit 282b. Further, the steering angular velocity deviation current determining unit 282 fades with respect to the target steering angular velocity Vst set by the target steering angular velocity setting unit 282c and the target steering angular velocity setting unit 282c that sets the target steering angular velocity Vst that is the target steering angular velocity Vs. And a cut-back fading processing unit 282d for performing processing. Further, the steering angular velocity deviation current determining unit 282 is a difference between the post-fade target steering angular velocity Vstf after the cut back fade processing unit 282d performs the fade processing and the actual steering angular velocity Vsa calculated by the actual steering angular velocity calculation unit 282a. A steering angular velocity deviation calculating unit 282e for calculating the steering angular velocity deviation ΔVs is provided. The steering angular velocity deviation current determination unit 282 includes a steering angular velocity deviation current setting unit 282f that sets the steering angular velocity deviation current Iv based on the steering angular velocity deviation ΔVs calculated by the steering angular velocity deviation calculation unit 282e.

  Based on the calculated steering angle θsc calculated by the steering angle calculation unit 73, the actual steering angular velocity calculation unit 282a calculates an actual steering angular velocity Vsa that is a change speed of the actual steering angle θs. The actual steering angular velocity calculation unit 282a calculates the actual steering angular velocity Vsa by differentiating the calculated steering angle θsc calculated by the steering angle calculation unit 73 with respect to time.

  In the cut back determination unit 282b, the steering wheel 101 is cut based on the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the actual steering angular velocity Vsa calculated by the actual steering angular velocity calculation unit 282a. It is determined whether or not it has been switched back. For example, the cut back determination unit 282b multiplies the calculated steering angle θsc calculated by the steering angle calculation unit 73 by the actual steering angular velocity Vsa calculated by the actual steering angular velocity calculation unit 282a ( = Θsc × Vsa) is determined to be cut when it is equal to or greater than 0, and is determined to be switched back when the multiplication value is less than 0.

FIG. 16A is a schematic diagram of a control map showing the correspondence between the calculated steering angle θsc, the vehicle speed Vc, and the target steering angular speed Vst when the steering wheel 101 is cut. FIG. 16B is a schematic diagram of a control map showing the correspondence between the calculated steering angle θsc, the vehicle speed Vc, and the target steering angular speed Vst when the steering wheel 101 is turned back.
The target steering angular velocity setting unit 282c calculates a target steering angular velocity Vst corresponding to the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the vehicle speed Vc. When the steering wheel 101 is cut, the target steering angular velocity setting unit 282c illustrates the calculated steering angle θsc, the vehicle speed Vc, and the target when the steering wheel 101 is cut as illustrated in FIG. A control map indicating the correspondence with the steering angular velocity Vst is used. On the other hand, when the steering wheel 101 is turned back, the target steering angular velocity setting unit 282c illustrates the calculated steering angle θsc and the vehicle speed Vc when the steering wheel 101 is turned back, as illustrated in FIG. And a control map showing the correspondence between the target steering angular velocity Vst. For example, the target steering angular velocity setting unit 282c is calculated based on an empirical rule that has been created in advance and stored in the ROM when the turning back determination unit 282b determines that the steering wheel 101 is cut. A value obtained by substituting the calculated steering angle θsc and the vehicle speed Vc into the control map illustrated in FIG. 16A showing the correspondence between the angle θsc and the vehicle speed Vc and the target steering angular speed Vst is set as the cut target steering angular speed Vst. To do. On the other hand, the target steering angular velocity setting unit 282c is calculated based on an empirical rule and is stored in the ROM in advance when the cut back determination unit 282b determines that the steering wheel 101 is turned back. A value obtained by substituting the calculated steering angle θsc and the vehicle speed Vc into the control map illustrated in FIG. 16B showing the correspondence between the angle θsc and the vehicle speed Vc and the target steering angular speed Vst is switched back as the target steering angular speed Vst. Set.

In the control map of FIG. 16A showing the case where the steering wheel 101 is cut, when the vehicle speed Vc is the same, the target is increased as the calculated steering angle θsc increases in the positive direction (rightward rotation direction). The steering angular velocity Vst is determined to be large. In addition, when the calculated steering angle θsc is the same, the target steering angular velocity Vst is determined to decrease as the vehicle speed Vc increases.
On the other hand, in the control map of FIG. 16B showing the case where the steering wheel 101 is turned back, when the vehicle speed Vc is the same, as the calculated steering angle θsc approaches the neutral position 0, the target steering angular velocity Vst is determined so as to approach 0 from the minus direction (so as to decrease in the minus direction). Further, when the calculated steering angle θsc is the same, the target steering angular velocity Vst is determined to increase (decrease in the minus direction) as the vehicle speed Vc increases.

Here, as shown in FIGS. 16A and 16B, the direction (sign) of the target steering angular velocity Vst differs between when the steering wheel 101 is cut and when it is turned back. If the cut back determination unit 282b repeatedly determines that it has been cut in a short time and that it has been cut back, the behavior may become unstable.
Accordingly, the cut-back fade processing unit 282d switches from the state where the cut-back determination unit 282b determines that the cut-back determination unit 282b is cut to the state where it is determined that the cut-back is performed, and from the state where it is determined that the cut-back is performed. When the state is determined to be cut, the target steering angular velocity Vst is gradually changed over a predetermined period. For example, a value that changes from the previous target steering angular velocity Vst to the current target steering angular velocity Vst in one second is determined periodically (for example, every 1 millisecond) as the post-fade target steering angular velocity Vstf.

  The steering angular velocity deviation calculation unit 282e subtracts the actual steering angular velocity Vsa calculated by the actual steering angular velocity calculation unit 282a from the post-fade target steering angular velocity Vstf after the cut back fade processing unit 282d performs the fade process. ΔVs is calculated (ΔVs = Vstf−Vsa).

FIG. 17 is a control map showing the correspondence between the steering angular velocity deviation ΔVs and the steering angular velocity deviation current Iv.
The steering angular velocity deviation current setting unit 282f calculates a steering angular velocity deviation current Iv corresponding to the steering angular velocity deviation ΔVs calculated by the steering angular velocity deviation calculation unit 282e. For example, the steering angular velocity deviation current setting unit 282f is based on the control map illustrated in FIG. 17 that shows the correspondence between the steering angular velocity deviation ΔVs and the steering angular velocity deviation current Iv, which is previously created based on an empirical rule and stored in the ROM. Then, the steering angular velocity deviation current Iv is calculated by substituting the steering angular velocity deviation ΔVs.

(Final sensor failure current determination unit)
The final sensor failure current determination unit 283 is obtained by adding the temporary sensor failure current Ief determined by the temporary sensor failure current determination unit 281 and the steering angular velocity deviation current Iv determined by the steering angular velocity deviation current determination unit 282. This value is finally determined as the sensor failure current Ie.

In the sensor failure current determination unit 28 configured as described above, when the sensor failure detection unit 27 detects a failure of the torque sensor 109, the sensor failure current that is the basis of the target current It supplied to the electric motor 110. When calculating Ie, the steering angular velocity deviation current Iv corresponding to the deviation between the target steering angular velocity Vst and the actual steering angular velocity Vsa is added. Therefore, even when the torque sensor 109 fails, the electric motor 110 is driven so that the rotational speed of the steering wheel 101 is ideal for the driver.
The temporary sensor failure current Ief determined by the temporary sensor failure current determination unit 281 is based on the temporary sensor failure base when the steering angle | θse | after the absolute value is equal to or smaller than a predetermined reference steering angle θse0. Since the current Ieba is 0, the current Ieba is 0 when the turning amount of the steering wheel 101 is small. Therefore, when the target current calculation unit 20 does not include the steering angular velocity deviation current determination unit 282 and the steering angular velocity deviation current Iv is not added to the sensor failure current Ie that becomes the target current It when the torque sensor 109 fails. The current for returning the steering angle θs to the neutral position is not supplied to the electric motor 110. However, in the target current calculation unit 20 according to the present embodiment, since the steering angular velocity deviation current Iv is always added to the sensor failure current Ie that becomes the target current It when the torque sensor 109 fails, the steering wheel 101 Even when the amount of cutting is small, a current for returning the steering angle θs to 0 is supplied to the electric motor 110. As a result, even when the turning amount of the steering wheel 101 is small, when the steering wheel 101 returns to the neutral position, the steering wheel 101 returns at an ideal return speed.
In the control maps illustrated in FIGS. 16A and 16B, the correspondence between the calculated steering angle θsc and the target steering angular velocity Vst is shown for each vehicle speed Vc, which is ideal for the driver in the entire vehicle speed region. The electric motor 110 is driven so that the rotational speed of the steering wheel 101 becomes a typical one.

  In the embodiment described above, the sensor failure current Ie is determined using the rotation angle (steering angle θs) of the steering wheel 101 calculated by the steering angle calculation unit 73 based on the output signal from the resolver 120. However, it is not particularly limited to such an embodiment. For example, a steering angle sensor that detects the rotation angle of the steering wheel 101 may be provided, and the sensor failure current Ie may be determined based directly on the detected value of the steering angle sensor.

  Further, the cut back determination unit 282b is configured to cut the steering wheel 101 based on the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the actual steering angular velocity Vsa calculated by the actual steering angular velocity calculation unit 282a. However, it is not particularly limited to such a mode. For example, the cut back determination unit 282b is similar to the determination unit 281cd in the return correction coefficient setting unit 281c, and the calculated steering angle θsc calculated by the steering angle calculation unit 73 and the substitution calculated by the substitution steering angle calculation unit 281a. When the multiplied value (= θsc × θsev) obtained by multiplying the calculated steering angular velocity θsev obtained by differentiating the steering angle θse with respect to time is greater than 0 (θsc × θsev> 0), it is determined that the cut is made. However, when the multiplication value is less than 0 (θsc × θsev <0), it may be determined that it has been switched back. Note that the motor rotation speed signal Vms (motor rotation speed Vm) from the motor rotation speed calculation unit 72 may be used as the calculated steering angular speed θsev.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 20 ... Target current calculation part, 21 ... Base current calculation part, 27 ... Sensor failure detection part, 28 ... Current determination part at the time of sensor failure, 281 ... Current determination part at the time of temporary sensor failure, 282 ... Steering angular velocity deviation Current determination unit, 283 ... Current determination unit at the time of final sensor failure

Claims (4)

An electric motor for applying an assisting force to the steering wheel of the vehicle;
Torque detecting means for detecting a steering torque of the steering wheel;
Steering angle detection means for detecting a steering angle which is a rotation angle of the steering wheel;
When the torque detection means is normal, based on the torque detected by the torque detection means, and when the torque detection means is not normal, the steering angle detected by the steering angle detection means and the target steering angular velocity Control means for controlling the driving force of the electric motor based on the deviation between the actual steering angular velocity and
Equipped with a,
The control means includes
A failure basic target current setting means for setting a failure basic target current that is a basis of a target current supplied to the electric motor when a failure occurs in the torque detection means based on the steering angle;
A deviation current setting means for setting a deviation current according to a deviation between the target steering angular velocity and the actual steering angular velocity;
The target current when a failure occurs in the torque detection means is determined based on the failure basic target current set by the failure basic target current setting means and the deviation current set by the deviation current setting means. A target current determining means;
An electric power steering apparatus comprising: a. 2. The electric power steering apparatus according to claim 1, wherein the control unit sets the target steering angular velocity based on the steering angle detected by the steering angle detection unit and the moving speed of the vehicle. 3. The electric power steering apparatus according to claim 1, wherein the deviation current setting unit increases the target steering angular velocity as the steering angle detected by the steering angle detection unit increases. When the steering wheel is cut , the deviation current setting means decreases the target steering angular velocity as the moving speed of the vehicle increases, and when the steering wheel is turned back, the electric power steering apparatus according to any one of claims 1 to 3, characterized in that to increase the steering angular velocity of about the target moving speed is greater of the vehicle.

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