JP2002046639A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device for vehicle capable of making steering with good responsiveness and a smooth return steering compatibly. SOLUTION: A steering control part 33 controls a steering actuator 2 on the basis of the target steering angle δ*. The control gain of the steering control part 33 can be changed by a gain setting part 35. When the steering is sensed by a steering sensing part 362, the gain setting part 35 sets large the control gain. When on the other hand, a return steering is sensed by a return steering sensing part 363, the control gain is set small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a vehicle, which is capable of changing the relationship between the operation of an operating member such as a steering wheel and the steering of a steering wheel.

[0002]

2. Description of the Related Art A mechanical connection between a steering wheel and a steering mechanism for turning a steering wheel is eliminated, an operation direction and an operation amount of the steering wheel are detected, and the steering mechanism is controlled based on the detection result. There has been proposed a vehicle steering system (so-called steer-by-wire system) in which a driving force from an actuator such as an electric motor is applied to a rack shaft (for example, a steer-by-wire system).
See JP-A-9-142330).

[0003] By adopting such a configuration, it is not necessary to mechanically connect the steering mechanism and the steering wheel. Therefore, it is possible to prevent the steering wheel from being pushed up at the time of a collision and to simplify the configuration of the steering mechanism. The weight can be reduced. Further, the degree of freedom of the arrangement position of the steering wheel is increased, and further, other operation members such as a lever or a pedal other than the steering wheel can be adopted.

In the vehicle steering apparatus having the above-described structure, the relationship between the operation of the steering wheel and the operation of the steering mechanism can be freely changed by electric control, so that the driving performance of the vehicle is dramatically improved. It is expected that it can be improved. For example, by obtaining a target yaw rate or a target lateral acceleration corresponding to an operating torque or an operating angle of a steering wheel, and controlling the operation of a steering mechanism based on these, it is possible to control the attitude of the vehicle, and to control the vehicle for steering. Exercise characteristics can be optimized.

[0005] The target turning angle of the steering mechanism is determined based on the target lateral acceleration and the target yaw rate based on the operation angle of the steering wheel, and is set to a value corresponding to these. At the time of undercut steering that increases the absolute value of the steering angle of the steered wheels (when steering away from the neutral position), it is necessary to quickly control the position of the rack shaft against the reaction force from the road surface There is. That is, since control with high responsiveness is required, it is necessary to tune the control gain of the steering mechanism for the target turning angle and the like as high as possible.

[0006]

However, at the time of return steering in which the absolute value of the turning angle of the steered wheels is reduced (at the time of steering in the direction toward the neutral position (straight forward steering position)), the direction of the road surface reaction force and The moving direction of the rack shaft becomes the same. Therefore, in the above-described conventional technology in which a high control gain is set in accordance with the turning steering, the movement of the rack shaft becomes oscillatory,
It is hard to expect smooth return steering.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned technical problems and to provide a vehicular steering apparatus capable of achieving both in-feed steering with good responsiveness and smooth return steering. .

[0008]

According to the first aspect of the present invention, a steering mechanism (2) is provided in response to an operation of an operation member (1) for steering a vehicle. A steering device for a vehicle that drives a steering wheel (4), a steering angle detecting means (362) for detecting a steering angle for increasing an absolute value of a steering angle of a steering wheel (4), and an operation of the operating member. When the steering control means (20, 31, 32, 33) for driving the steering mechanism and the undercut steering detecting means detect the undercut steering, the steering control is performed more than when the undercut steering is not detected. And a control gain setting means (35) for setting a large control gain of the steering control means. Note that the numbers in parentheses represent corresponding components and the like in embodiments described later. Hereinafter, the same applies in this section.

Preferably, there is no mechanical connection between the operating member and the steering mechanism, and the steering mechanism is electrically controlled in accordance with the operation of the operating member. According to the present invention, when the turning steering is detected, the control gain of the steering control means is increased, while when the turning steering is not detected, the control gain is set relatively small. As a result, the steering mechanism can be operated with good responsiveness during the turning steering, and the steered wheels can be smoothly guided to the neutral position during the return steering.

According to a second aspect of the present invention, a steering mechanism (2, 3) is provided in response to an operation of an operation member (1) for steering a vehicle.
Steering device for a vehicle, comprising: a steering wheel (4)
Return steering detecting means (363) for detecting return steering for reducing the absolute value of the turning angle of the steering wheel, and steering control means (20, 31, 32) for driving the steering mechanism based on the operation of the operating member. 33) and control gain setting means (35) for setting the control gain of the steering control means smaller when the return steering detection means detects the return steering than when the return steering is not detected. A vehicle steering system characterized by including:

According to the present invention, when return steering is detected, the control gain of the steering control means is set small.
As a result, smooth return steering can be realized without sacrificing the responsiveness of the control of the steering mechanism during the turning steering. According to a third aspect of the present invention, there is provided a vehicle steering apparatus for driving a steering mechanism (2, 3) in response to an operation of an operation member (1) for steering a vehicle, wherein a steering wheel (4) is rotated. Infeed steering detection means (362) for detecting infeed steering for increasing the absolute value of the steering angle, and return steering detection means (363) for detecting return steering for decreasing the absolute value of the steering angle of the steered wheels. Steering control means (20, 20) for driving the steering mechanism based on the operation of the operation member.
31, 32, 33), the control gain of the steering control means is made larger when the turning steering detecting means detects the turning steering than when the returning steering detecting means detects the returning steering. And a control gain setting means (35) for setting.

According to the present invention, the turning steering and the returning steering are respectively detected. Then, the control gain of the steering control means for driving the steering mechanism based on the target turning angle is set to be large at the time of the turning steering, and is set to be small at the time of the returning steering. As a result, it is possible to achieve both the turning steering with good responsiveness and the smooth return steering. The invention according to claim 4 further includes an operation angle sensor (11) for detecting an operation angle of the operation member and outputting detection values having different signs for leftward steering and rightward steering. 4. The control device according to claim 1, wherein the control unit detects the turning-in steering based on the fact that the sign of the detection value output from the operation angle sensor and the time derivative of the detection value are the same. It is a steering device for vehicles of a statement.

Further, the invention according to claim 5 further includes an operation angle sensor (11) for detecting an operation angle of the operation member and outputting detection values having different signs for leftward steering and rightward steering, The return steering detecting means detects return steering based on a difference between a sign of a detection value output by the operation angle sensor and a time derivative of the detection value. A vehicle steering system according to claim 2 or 3. For example, it is assumed that the operation angle sensor outputs an operation angle detection value of a positive sign for rightward steering and outputs an operation angle detection value of a negative sign for leftward steering.
In this case, if the detection value of the operation angle sensor takes a positive sign value and the time derivative of this detection value takes a positive value, it means that the operation angle increases to the right. I do.
Conversely, if the output detection value of the operation angle sensor takes a negative value and the time derivative of the detection value takes a negative value,
This means that the operation angle tends to increase to the left. Therefore, if the sign of the output detection value of the operation angle sensor and the time derivative thereof are the same, it can be determined that the undercut steering is being performed.

On the other hand, if the detection value of the operation angle sensor takes a positive value and its time derivative takes a negative value, the operation member is returned from the right steering state to the neutral position. Means in the process. In addition, if the detection output value of the operation angle sensor takes a negative value and its time derivative takes a positive value, the operation member is in the left steering position and is heading toward the neutral position. Means Therefore, it is possible to detect that the return steering is being performed based on the difference between the sign of the output detection value of the operation angle sensor and the sign of the time differential value thereof.

In the case of adopting the structure of claim 3, it is preferable to combine the features described in both claim 4 and claim 5. The control gain may be changed by changing the ratio (gear ratio) of the steering angle of the steering mechanism to the operation angle of an operation member such as a steering wheel. Claims 1 to 5
In any of the inventions described in any of the above, the target turning angle setting means (31, 31) for setting the target turning angle according to the operation of the operating member.
32) is preferably provided. In this case,
It is preferable that the steering control section drives and controls the steering mechanism based on the target turning angle set by the target turning angle setting means.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a conceptual diagram for explaining a basic configuration of a vehicle steering system according to an embodiment of the present invention. This steering apparatus for a vehicle is a so-called steer-by-wire system, in which the operation of a steering actuator 2 driven in accordance with a rotation operation of a steering wheel (operation member) 1 is controlled by a steering gear 3 on front left and right wheels. 4 (steering wheel)
Thus, steering is achieved without mechanically connecting the steering wheel 1 and the steering gear 3 to each other. In this case, the steering actuator 2 and the steering gear 3 constitute a steering mechanism.

The steering actuator 2 can be constituted by an electric motor such as a known brushless motor. The steering gear 3 controls the rotational movement of the output shaft of the steering actuator 2 by using a steering rod 7.
A motion conversion mechanism (such as a ball screw mechanism) for converting the motion into a linear motion in the axial direction (vehicle width direction). The movement of the steering rod 7 is controlled by a knuckle arm 9 via a tie rod 8.
To cause the knuckle arm 9 to rotate. As a result, the wheel 4 supported by the knuckle arm 9
Steering is achieved.

The steering wheel 1 is connected to a rotating shaft 10 rotatably supported on the vehicle body. A reaction force actuator 19 for applying a steering reaction force to the steering wheel 1 is attached to the rotating shaft 10. Specifically, the reaction force actuator 19
Can be constituted by an electric motor such as a brushless motor having an output shaft integrated with the rotating shaft 10. An elastic member 3 made of a spiral spring or the like is provided at an end of the rotating shaft 10 opposite to the steering wheel 1.
0 is connected to the vehicle body. This elastic member 30
Means that the reaction force actuator 19 is
When no torque is applied to the steering wheel 1, the steering wheel 1 is returned to the straight steering position by the elastic force.

In order to detect an operation input value of the steering wheel 1, an operation angle sensor 11 for detecting an operation angle δh corresponding to a rotation angle of the rotation shaft 10 is provided. The rotating shaft 10 is provided with a torque sensor 12 for detecting an operating torque T applied to the steering wheel 1. Operation angle sensor 11
Outputs a positive detection value when the steering wheel 1 is in a rightward steering position where the steering wheel 1 is steered rightward from a neutral position (straight forward steering position), and the steering wheel 1 is steered leftward from the neutral position. When the vehicle is at the left steering position, a negative detection value is output.

On the other hand, as an output value sensor for detecting the output value of the steering actuator 2, the steering angle δ
Is provided. The steering angle sensor 13 can be configured by a potentiometer or the like that detects the amount of operation of the steering rod 7 by the steering actuator 2. The turning angle δ is, for example,
It takes a positive value when the steering wheel 4 is turned to the right, and takes a negative value when the steering wheel 4 is turned to the left.

The operation angle sensor 11, the torque sensor 12, and the steering angle sensor 13 are connected to a steering system control device 20 (steering control means) including a computer. The control device 20 further includes a lateral acceleration G of the vehicle.
A lateral acceleration sensor 15 for detecting y, a yaw rate sensor 16 for detecting a yaw rate γ of the vehicle, and a speed sensor 14 for detecting a vehicle speed V are connected. In addition, as a variable correlated with the lateral acceleration Gy and the yaw rate γ,
In addition to the operation angle δh and the vehicle speed V, for example, a sensor for detecting the wheel speed may be connected to the control device 20.

The control device 20 is connected to the steering actuator 2 and the reaction force actuator 19 via drive circuits 22 and 23.
And control. FIG. 2 is a block diagram for explaining the control contents of the control device 20. The control device 20 implements the operation of each functional unit shown in FIG. 2 by program processing by a computer. Explaining the symbols in the figure, Gy is the lateral acceleration of the vehicle detected by the lateral acceleration sensor 15, Gy ^* is the target value of the lateral acceleration, γ is the yaw rate of the vehicle detected by the yaw rate sensor 16, δ
Is the turning angle of the steering mechanism detected by the turning angle sensor 13, δ ^* is the target value of the turning angle, δh is the operation angle detected by the operation angle sensor 11, and V is the vehicle speed detected by the speed sensor 14. , T is the operating torque detected by the torque sensor 12, T ^* is the target value of the operating torque, i ^* is the target value of the drive current of the steering actuator 2, and ih ^* is the target value of the drive current of the reaction force actuator 19. Show.

The target lateral acceleration calculator 31 calculates the target lateral acceleration Gy ^* based on the operation angle δh by Gy ^* = K1 · δh ^.
Ask for. K1 is the target lateral acceleration Gy with respect to the operation angle δh
^* The gain is adjusted so that optimal control can be performed. Since the possible lateral acceleration decreases as the vehicle speed decreases, the gain K1 is a function of the vehicle speed V. On the other hand, based on the operation angle δh detected by the operation angle sensor 11,
The target torque T ^* is obtained by the target torque calculator 25. Specifically, the target torque T ^* is T ^* = K2 · δh
(However, K2 is a gain of the target torque T ^* with respect to the operation angle δh.) This target torque T
^* Deviation of the operation torque T with respect to (T ^* -T) is found,
Based on this, the reaction force actuator control unit 26 sets the target drive current ih ^* of the reaction force actuator 19.
This target drive current ih ^* is determined by ih ^* = G4 · (T ^* −T). Here, G4 is a transfer function, for example, G4 = Kd (1 + 1 / (Td · s)). Kd is a gain, Td is a time constant, and s is a Laplace operator.

The target turning angle calculation unit 32 obtains a target steering angle [delta] ^* is the target turning angle based on the lateral acceleration [delta] _G ^*, by adding the target steered angle [Delta] [gamma] ^* based on the yaw rate, the target rolling determine the steering angle _{^{δ * = δ G * + δγ}} *. The target turning angle δ _G ^* based on the lateral acceleration is given by δ _G ^* = G 1 · (Gy ^* ) according to the deviation (Gy ^* −Gy) of the actual lateral acceleration Gy of the vehicle 50 from the target lateral acceleration Gy ^* and the transfer function G 1 ^. -Gy).
On the other hand, the target steering angle δγ based on the yaw rate
^* Is a deviation (Gy ^* −γ ·) of the integrated value γ · V of the actual yaw rate γ of the vehicle 50 and the vehicle speed V from the target lateral acceleration Gy ^* .
V), and the deviation and the transfer function G2 are used to calculate δγ
^* = G2 · (Gy ^* −γ · V) Between the target yaw rate γ ^* and the target lateral acceleration Gy ^* , γ ^* V = G
y ^* holds, the deviation (Gy ^* −γ ·
V) = (γ ^* −γ) V corresponds to the deviation of the actual yaw rate γ from the target yaw rate γ ^* .

Based on the target turning angle δ ^* obtained in this way, the steering control unit 33 executes drive control of the steering actuator 2. Specifically, the steering control unit 33
Deviation of actual turning angle δ from target turning angle δ ^* (δ ^* −
δ), and using this deviation (δ ^* −δ) and the transfer function G3, a target drive current i ^* = G3 · (δ ^* −δ) is calculated.
The steering actuator 2 is feedback-controlled based on the target drive current i ^* .

The above-mentioned transfer functions G1, G2, G3 are determined, for example, as in the following equations (1), (2) and (3), respectively.

[0027]

(Equation 1)

Gains Ka, Kb, Kc and time constant T
Although a, Tb, and Tc are appropriately adjusted so that optimum control can be performed, in particular, in this embodiment, the responsiveness and the responsiveness in the undercut steering that increases the absolute value of the turning angle δ of the steered wheels 4 are improved. In order to achieve both the smoothness of the return steering which reduces the absolute value of the steering angle δ of the steered wheels 4, the target drive current i ^* for the deviation between the target steering angle δ ^* and the actual steering angle δ A gain setting unit 35 for setting a gain (control gain for drive control of the steering mechanism) Kc is provided.

Further, a steering state detector 36 for detecting the turning steering and the returning steering is provided. The steering angle detection unit 36 is provided with an operation angle δh detected by the operation angle sensor 11. The steering state detection unit 36 includes an operation angular velocity detection unit 361 that detects a time differential value δh ′ (operation angular velocity) of the operation angle δh, and an operation angle δh.
And a turning steering detecting section 362 for detecting turning steering based on the operating angular velocity δh ', and a return steering detecting section 363 for detecting returning steering based on the operating angle δh and the operating angular velocity δh'.

The infeed steering detecting section 362 and the return steering detecting section 363 provide a product δ of the operation angle δh and the operation angular velocity δh ′.
Infeed steering and return steering are detected based on h · δh ′. That is, if δh · δh ′> 0, the sign of the operation angle δh and the sign of the operation angular velocity δh ′ become the same, and | δh | tends to increase, and the steering angle δ of the steered wheels 4 becomes larger. It can be determined that the undercut steering for increasing the absolute value is performed. On the other hand, when δh · δh ′ takes a negative value, the return steering detection unit 363 determines that return steering is being performed. That is, if δh · δh ′ <0, it means that the sign of the operation angle δ and the sign of the operation angular velocity δh ′ are different. Therefore,
Since the absolute value of the operation angle δh tends to decrease,
It can be determined that return steering for decreasing | δ | is being performed. The detection outputs of the in-feed steering detection section 362 and the return steering detection section 363 are output to the gain setting section 35.
Is to be given.

FIG. 3 is a flow chart for explaining the contents of processing by the control gain setting section 35. When the undercut steering detecting section 362 detects the undercut steering (Step S)
1 YES), the control gain Kc of the steering control unit 33 is
The value is set to a relatively large value KL (step S2). No infeed steering is detected (NO in step S1),
If the return steering detection unit 363 has detected return steering (YES in step S3), the control gain Kc of the steering control unit 33 is set to a relatively small value KS (KS <KL) (step S4). The infeed steering detection unit 362 has not detected infeed steering (NO in step S1), and
If the return steering detection unit 363 has not detected return steering (NO in step S3), the control gain Kc of the steering control unit 33 is a value K0 (KL> K0 ≧ K) between KL and KS.
S) is set (step S5). Where KS = K
It may be 0.

The large control gain KL is set so that good responsiveness can be obtained at the time of turning steering, and the small control gain KS is set so that vibration and the like do not occur at the time of return steering. Thus, the steering mechanism is driven with good responsiveness during the turning steering, and the steering wheel 1 and the steering wheel 4 can be smoothly guided to the neutral position without causing vibration during the return steering. FIG. 4 is a flowchart for explaining the second embodiment of the present invention. In the description of this embodiment, reference will be made again to FIGS. 1 and 2 described above.
FIG. 4 shows processing by the gain setting unit 35 of FIG.

In the second embodiment, the gain setting unit 3
5 refers to only the output of the undercut steering detection unit 362,
The control gain Kc of the steering control unit 33 is variably set. That is, in this embodiment, the steering state detector 36 includes:
It is not necessary to provide the return steering detecting unit 363. More specifically, if the turning steering is detected by the turning steering detecting unit 362 (YES in step S11), the gain setting unit 35 sets the control gain Kc to a relatively large value KL (step S12). On the other hand, if the undercut steering is not detected (step S1)
1), the control gain Kc is set to a relatively small value K0 (K
L> K0) (step S13).

The large control gain KL is set so that good responsiveness can be obtained at the time of turning steering, and the small control gain K0 is set so that vibration and the like do not occur at the time of return steering. This makes it possible to realize a vehicle steering system that achieves both good responsiveness at the time of in-feed steering and smoothness at the time of return steering. FIG. 5 is a flowchart for explaining the third embodiment of the present invention. In the description of this embodiment, reference will be made again to FIGS. 1 and 2 described above. FIG. 5 shows the gain setting unit 3 of FIG.
5 is shown.

In the third embodiment, the gain setting unit 3
5 variably sets the control gain Kc of the steering control unit 33 with reference to only the output of the return steering detecting unit 363. That is, in this embodiment, it is not necessary for the steering state detection unit 36 to be provided with the undercut steering detection unit 362. More specifically, the gain setting unit 35 sets the control gain Kc to a relatively small value KS (step S22) when the return steering is detected by the return steering detection unit 363 (YES in step S21). On the other hand, if the return steering is not detected (N in step S21)
O), the control gain Kc is set to a relatively large value KL (KL> K
S) (step S13).

The large control gain KL is set so that good responsiveness can be obtained at the time of turning steering, and the small control gain KS is set so that vibration or the like does not occur at the time of return steering. This makes it possible to realize a vehicle steering system that achieves both good responsiveness at the time of in-feed steering and smoothness at the time of return steering. The three embodiments of the present invention have been described above, but the present invention can be embodied in other forms. For example,
The control of the steering mechanism can be performed using an arbitrary control law such as PI (proportional integral) control, P (proportional) control, PD (proportional derivative) control, and PID (proportional integral derivative) control.

In the above embodiment, the control gain K
The description has been given by taking the change of the control gain Kc as an example.
At the same time, other control gains Ka and Kb may be changed. That is, the control gains Ka, Kb, and Kc may be set to be relatively large during the turning steering, and the control gains Ka, Kb, and Kc may be set to a relatively small value during the return steering. further,
The present invention is not limited to the above-described steer-by-wire system, and is widely applied to a vehicle steering device capable of changing a correspondence relationship between an operation angle of an operation member and a steering angle of a steering mechanism. can do. For example, in a system in which the ratio (gear ratio) of the steering angle of the steering mechanism to the operation angle of the operation member is variable, the control gain can be changed by changing the gear ratio.

In the above-described embodiment, the two-wheeled vehicle 2
Although the case where one wheel can be steered as a steering wheel has been described, the present invention may be applied to a four-wheel steering system in which all four wheels are steered. Further, in the above-described embodiment, an example in which the steering wheel 1 is used as the operation member has been described. However, other operation members such as a lever and a pedal may be used.

In addition to these, various design changes can be made within the scope of the matters described in the claims.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a basic configuration of a vehicle steering system according to an embodiment of the present invention.

FIG. 2 is a block diagram for explaining the contents of steering control.

FIG. 3 is a flowchart illustrating a control gain setting process for steering control.

FIG. 4 is a flowchart illustrating a control gain setting process according to another embodiment of the present invention.

FIG. 5 is a flowchart illustrating a control gain setting process according to still another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering actuator 11 operating angle sensor 12 torque sensor 13 turning angle sensor 14 speed sensor 15 lateral acceleration sensor 16 yaw rate sensor 20 steering system control device 33 steering control unit 35 gain setting unit 36 steering state detecting unit 361 operation angular speed Detector 362 Infeed steering detector 363 Return steering detector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62D 137: 00 B62D 137: 00 (72) Inventor Katsushi Nishizaki 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Koyo Inside Seiko Co., Ltd. (72) Inventor Masaya Segawa 3-5-8 Minamisenba, Chuo-ku, Osaka Mitsuyo Seiko Co., Ltd. F-term (reference) 3D032 CC12 DA03 DA04 DA15 DA23 DA29 DA33 DD06 EB04 EB16 EC21

Claims (5)

[Claims] 1. A vehicle steering device for driving a steering mechanism in response to an operation of an operation member for steering a vehicle, wherein a turning steering for increasing an absolute value of a turning angle of a steering wheel is detected. Steering control means for driving the steering mechanism based on the operation of the operating member; and when the steering control is not detected, the steering control is not detected. A control gain setting means for setting a control gain of the steering control means to be larger than that of the steering control means. 2. A steering apparatus for a vehicle for driving a steering mechanism in accordance with an operation of an operation member for steering a vehicle, wherein a return steering for reducing an absolute value of a steering angle of a steered wheel is detected. Return steering detection means, steering control means for driving the steering mechanism based on operation of the operation member, and when the return steering detection means detects return steering, when return steering is not detected. Control gain setting means for setting a control gain of the steering control means to be smaller than that of the steering control means. 3. A steering apparatus for a vehicle for driving a steering mechanism in accordance with an operation of an operation member for steering a vehicle, wherein a turning steering for increasing an absolute value of a turning angle of a steering wheel is detected. Turning steering detecting means for performing steering control, returning steering detecting means for detecting returning steering for reducing the absolute value of the steering angle of a steered wheel, and steering controlling means for driving the steering mechanism based on operation of the operating member. Control gain setting means for setting the control gain of the steering control means to be larger than when the return steering detection means is detecting return steering when the cut steering detection means is detecting cut steering. And a steering device for a vehicle. 4. An operation angle sensor for detecting an operation angle of the operation member and outputting detection values having different signs for leftward steering and rightward steering; 4. The vehicle steering system according to claim 1, wherein the on-board steering is detected based on the fact that the sign of the detected value output by the controller and the time derivative of the detected value are the same. . 5. An operation angle sensor for detecting an operation angle of the operation member and outputting a detection value having a different sign for leftward steering and rightward steering, wherein the return steering detecting means includes an operation angle sensor. 4. The vehicle steering apparatus according to claim 2, wherein the return steering is detected based on a difference between a sign of the detection value output by the controller and a sign of a time differential value of the detection value. .