JP2001030931A - Vehicular steering gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering gear capable of preventing the steering feeling from being degraded even when the vehicular attitude is controlled to stabilize the vehicle behavior in a vehicle to change its steering angle by operating an operation member not mechanically connected to a wheel. SOLUTION: The operation reaction of an operation member 1 including the reaction component corresponding to a manipulated variable of the operation member 1 and the reaction component corresponding to the deviation in steering angle which is obtained by subtracting the actual steering angle of a wheel 4 from the indicated steering angle corresponding to the manipulated variable of the operation member 1, is computed. The attitude of the vehicle is controlled by at least a steering actuator 2 for stabilization so that the vehicle behavior stabilizes. When the vehicle behavior is stable, an reaction actuator 19 is controlled to generate the computed operation reaction. When the vehicle behavior is unstable, the reaction actuator 19 is controlled so as to generate the operation reaction which is obtained by subtracting the reaction component corresponding to the deviation in steering angle from the operated operation reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system capable of changing a steering angle without mechanically connecting an operating member such as a steering wheel to wheels.

[0002]

2. Description of the Related Art In a vehicle in which the actual steering angle of a wheel is changed by a steering actuator driven in accordance with the operation angle of the steering wheel without mechanically connecting the steering wheel to the wheel, the operation of the steering wheel is performed. Providing a reaction force actuator that generates a reaction force,
A simulated steering reaction is applied to the driver. That is, a steering angle deviation obtained by subtracting the actual steering angle from the indicated steering angle corresponding to the steering wheel operation angle is calculated, and an operation including a component proportional to the steering angle deviation and a component proportional to the steering wheel operation angle is performed. The reaction force is given.

[0003]

Since the operation reaction force includes a component proportional to the steering angle deviation, excessive steering due to insufficient operation reaction force can be prevented, and the response delay of the steering actuator is apparently reduced. Drivers can feel as if they have improved.

However, in a vehicle in which the attitude of the vehicle is controlled by the steering actuator in order to stabilize the behavior of the vehicle, an operation reaction force component proportional to such a steering angle deviation causes the steering wheel of the driver to control the attitude during the attitude control. There is a problem in that the steering feel fluctuates irrespective of the operation intention and the steering feeling is reduced.

[0005] It is an object of the present invention to provide a vehicle steering system capable of solving the above-mentioned problems.

[0006]

SUMMARY OF THE INVENTION The present invention provides a vehicle in which the actual steering angle can be changed by a steering actuator driven in accordance with the operation amount of the operation member without mechanically connecting the operation member to wheels. In the steering apparatus, a reaction force actuator for generating an operation reaction force of the operation member, a unit for detecting an operation amount of the operation member, a unit for detecting an actual steering angle of the wheel, and the detected operation member Means for calculating a steering angle deviation obtained by subtracting the detected actual steering angle from the commanded steering angle corresponding to the operation amount of the operation member, a reaction force component corresponding to the operation amount of the operation member, and corresponding to the steering angle deviation. Means for calculating an operation reaction force including a reaction force component to be operated, means for controlling the reaction force actuator so as to generate an operation reaction force, means for determining whether vehicle behavior is unstable, Stable when behavior is unstable Means for controlling the attitude of the vehicle by at least the steering actuator, when the vehicle behavior is not unstable, the reaction force actuator is controlled to generate the calculated operation reaction force, When the vehicle behavior is unstable, the reaction force actuator is controlled to generate an operation reaction force obtained by subtracting a reaction force component corresponding to the steering angle deviation from the calculated operation reaction force. And

According to the configuration of the present invention, when the attitude control is performed due to unstable vehicle behavior, the reaction force component corresponding to the steering angle deviation is subtracted from the operation reaction force. The variation of the angular deviation does not affect the operation reaction force.

In the present invention, a means for storing a predetermined maximum operation reaction force is provided, and when the vehicle operation is not unstable and the calculated operation reaction force exceeds the stored maximum operation reaction force, It is preferable that the reaction force actuator is controlled so as to generate the maximum operation reaction force instead of the calculated operation reaction force. As a result, when the vehicle behavior is not unstable, for example, when the wheels are fitted into the rut, the steering angle deviation sharply increases, and the calculated value of the operation reaction force including the reaction force component corresponding to the steering angle deviation increases. However, the operation reaction force generated by the reaction force actuator does not exceed the maximum operation reaction force. Therefore, even when such a sharp increase in the steering angle deviation occurs, the correction steering for canceling the increase in the steering angle deviation by operating the operation member is not hindered.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a vehicle steering system shown in FIG. 1, a steering actuator 2 driven in accordance with a rotation operation of a steering wheel (operating member) 1 moves.
The actual steering angle changes by being transmitted to the front left and right wheels 4 via the steering gear 3. Thereby, without mechanically connecting the steering wheel 1 to the wheel 4,
The actual steering angle can be changed by the actuator 2.

The steering actuator 2 can be constituted by an electric motor such as a known brushless motor. The steering gear 3 has a motion conversion mechanism that converts the rotational motion of the output shaft of the steering actuator 2 into a linear motion of the steering rod 7. The movement of the steering rod 7 is transmitted to the wheel 4 via the tie rod 8 and the knuckle arm 9. As the steering gear 3, a known gear can be used, and the configuration is not limited as long as the movement of the steering actuator 2 can be converted into the actual steering angle of the wheel 4. In a state where the steering actuator 2 is not driven, the wheel alignment is set so that the wheels 4 can return to the straight steering position by the self-aligning torque.

The steering wheel 1 is connected to a rotating shaft 10 rotatably supported by the vehicle body. A reaction force actuator 19 for generating an operation reaction force of the steering wheel 1 is provided. 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 30 for providing elasticity for returning the steering wheel 1 to the straight steering position is provided. The elastic member 30 is, for example, a rotary shaft 1
It can be constituted by a spiral spring that gives elasticity to zero. When the reaction force actuator 19 does not apply torque to the rotating shaft 10, the steering wheel 1 can return to the straight steering position by its elasticity.

The operation amount of the steering wheel 1 is an operation angle δ corresponding to the rotation angle of the rotary shaft 10.
An angle sensor 11 for detecting h is provided. As a value corresponding to the operation reaction force of the steering wheel 1,
A torque sensor 12 for detecting an operation torque T transmitted by the rotating shaft 10 is provided.

A potentiometer 13 for detecting the amount of operation of the steering rod 7 by the steering actuator 2 is provided as a value corresponding to the actual steering angle δ of the wheel 4.

The steering actuator 2, the reaction force actuator 19, the angle sensor 11, the torque sensor 12, and the potentiometer 13 are connected to a steering system controller 20 constituted by a computer. Further, the steering system control device 20 detects a lateral acceleration sensor 15 for detecting a lateral acceleration Gy of the vehicle, a yaw rate sensor 16 for detecting a yaw rate γ of the vehicle, and a vehicle speed v as variables related to the sideslip angle of the vehicle. Speed sensor 14 is connected.

A braking system for braking the front, rear, left and right wheels 4 of the vehicle is connected to the steering device. That is, the master cylinder 52 generates a braking pressure corresponding to the depression force of the brake pedal 51. The braking pressure is amplified by the braking pressure control unit 53 and distributed to the braking devices 54 of the wheels 4, and the braking devices 54 apply a braking force to the wheels 4. The braking pressure control unit 53 is connected to a traveling system control device 60 constituted by a computer. The traveling system control device 60 includes a steering system control device 20, a braking force sensor 61 for individually detecting the braking force of each wheel 4, and a wheel speed sensor 62 for individually detecting the rotation speed of each wheel 4. Connected. The traveling system control device 60 controls the rotation speed of each wheel 4 detected by the wheel speed sensor 62 and the braking force detection sensor 61.
Pressure control unit 5 so that the braking pressure can be amplified and distributed according to the feedback value of
3 is controlled. This makes it possible to individually control the braking force of each wheel. The braking pressure control unit 53 can generate a braking pressure by a built-in pump according to a signal from the traveling system control device 60 even when the brake pedal 51 is not operated.

Further, an actuator 70 for controlling the opening of a throttle valve in a fuel supply system to a driving engine of a vehicle is connected to the traveling system control device 60, and a signal from the traveling system control device 60 controls the throttle valve. It is possible to control the driving force of the vehicle by changing the opening.

The control procedure in the embodiment of the present invention will be described with reference to the flowchart of FIG. In the following description, the steering angle and the sideslip angle of the vehicle are assumed to be positive in the case of going to the left or right with respect to the straight traveling direction of the vehicle, and negative in the case of going to the other side.

First, the vehicle speed v and the lateral acceleration G by each sensor
The detection data of the operation amount, the operation angle δh, and the operation torque T of the steering rod 7 corresponding to y, the yaw rate γ, and the actual steering angle δ are read (step 1).

Next, the target operation torque T ^{* is used} as the operation reaction force ^.
Is calculated (step 2). Therefore, first, the steering system control device 20 corresponds to the operation amount δs of the steering rod 7 detected by the potentiometer 13 from the indicated steering angle δh ′ corresponding to the operation angle δh of the steering wheel 1 detected by the angle sensor 11. A steering angle deviation (δh′−δ) obtained by subtracting the actual steering angle δ is calculated. The operation angle δh of the steering wheel 1 and the designated steering angle δ
The corresponding relationship with h ′ and the corresponding relationship between the operation amount δs of the steering rod 7 and the actual steering angle δ are determined in advance and stored in the steering system controller 20. Next, the steering system controller 20 sets the target operation torque T ^* as a reaction force component Th ^* corresponding to the operation angle δh of the steering wheel 1 and a reaction force component corresponding to the steering angle deviation (δh′−δ). An operation reaction force including the component ΔT is calculated. In the present embodiment, the target operation torque T ^* is calculated by the following equation using Ka and Kb as proportional constants. T ^* = Th ^* + ΔT = Ka · δh + Kb · (δh′−
δ)

Next, the steering system controller 20 determines whether or not the vehicle behavior is in an unstable state based on the detected variable correlated with the side slip angle of the vehicle (step 3).
This determination can be made based on, for example, whether or not the absolute value of the sideslip angle of the vehicle or the absolute value of the sideslip speed (the changing speed of the sideslip angle of the vehicle) is equal to or greater than a predetermined set value.
That is, in FIG. 3, the vehicle 100 travels along the path shown by the broken line when there is no side slip, and when the side slip angle of the vehicle increases due to the moment shown by the arrow A, the vehicle 100 enters an oversteer state as shown by the two-dot chain line and spins. When the side slip angle of the vehicle is increased by the moment indicated by the arrow B, the vehicle may drift into an understeer state as indicated by a dashed line. The absolute value of the skid angle and the set value of the skid speed of the vehicle are determined so that it is possible to determine whether or not the vehicle behavior is unstable before such a spin or drift occurs. As shown in FIG. 4, when the vehicle 100 that turns at the vehicle speed v in the direction indicated by the arrow 40 does not skid, the lateral acceleration Gy acting in the direction indicated by the arrow 41 and the yaw rate γ acting in the direction indicated by the arrow 42. Is Gy = γ · v. When the yaw rate γ in the direction indicated by the arrow 42 decreases due to skidding of the vehicle, the vehicle enters an oversteer state, and when the yaw rate γ increases, the vehicle enters an understeer state. Side slip angle β of the vehicle
And the variables Gy, γ, and v are stored in the control device 20, and the side slip angle β of the vehicle is determined from the relationship. In the present embodiment, the side slip angle β of the vehicle is a time integration value of Gy / v−γ at a preset time, that is, ∫
(Gy / v-γ) dt = β.

When the vehicle behavior is not in an unstable state in step 3, the steering system controller 20 uses the maximum torque Tmax stored in advance as the maximum operation reaction force and the target operation torque which is the operation reaction force calculated in step 2 It is determined whether T ^* is exceeded (step 4).

When the target operation torque T ^* does not exceed the maximum torque Tmax in step 4, the reaction force actuator 19 is controlled to generate the target operation torque T ^* which is the operation reaction force calculated in step 2 ( Step 5). That is, the steering system control device 20 controls the reaction force actuator 19 such that the deviation obtained by subtracting the operation torque T detected by the torque sensor 12 from the target operation torque T ^* becomes zero.

When the target operating torque T ^* exceeds the maximum torque Tmax in step 4, the maximum torque Tma
The reaction force actuator 19 is controlled so as to generate x (step 6). That is, the maximum torque Tmax
The steering system control device 20 controls the reaction force actuator 19 so that the deviation obtained by subtracting the operation torque T detected by the torque sensor 12 from the above becomes zero.

When the vehicle behavior is unstable in step 3, the steering angle deviation (δh'-δ) is calculated from the target operation torque T ^*, which is the operation reaction force calculated in step 2.
Operation reaction force Th ^* = reduction of reaction force component ΔT corresponding to
The reaction force actuator 19 is controlled to generate Ka · δh (step 7). That is, the operation reaction force T
The steering system control device 20 controls the reaction force actuator 19 so that the deviation obtained by subtracting the operation torque T detected by the torque sensor 12 from h ^* becomes zero.

If the vehicle behavior is not unstable in step 3 and the operation reaction force is controlled in step 5 or step 6, the steering system controller 20 controls the steering actuator 2 to set the steering angle to the target value. δ ^*
Is performed (step 8). In the present embodiment, the target steering angle δ ^* is a function K2 of an operation angle δh, which is an operation amount of the steering wheel 1, and the function K2
Are predetermined and stored in the steering system control device 20. The steering system control device 20 controls the steering actuator 2 so that the deviation obtained by subtracting the actual steering angle δ from the target steering angle δ ^* determined according to the detected operation angle δh based on this function becomes zero. Incidentally, the target steering angle [delta] ^* as a function of the detected operating torque T, the target steering angle from the detected operating torque T [delta] ^*
May be determined.

When the vehicle behavior is unstable in step 3 and the operation reaction force is controlled in step 7, it is determined whether or not steering for canceling the vehicle side slip angle β calculated in step 3 is performed. It is determined (step 9). In the present embodiment, the actual steering angle immediately before the vehicle behavior is determined to be in an unstable state in step 3 is set to δo, and it is determined whether or not the current actual steering angle δ is δ = δo−β. . That is, as shown in (1) of FIG. 5, the direction indicated by the broken line in which the vehicle 100 proceeds when there is no skid, and the vehicle 100 that has skid in the oversteer state.
Is the side slip angle of the vehicle formed by the vehicle center line indicated by the one-dot chain line along the front-rear direction. Assuming that there is no side slip, the current steering angle of the vehicle 100 can be regarded as the actual steering angle δo immediately before the vehicle behavior is determined to be in an unstable state. Therefore, the actual steering angle δ at the present time is δ = δo−β
In this case, steering is performed to cancel the side slip angle β of the vehicle. Vehicle 1 without side skidding
Since the traveling direction of 00 corresponds to the traveling direction of the center of gravity of the vehicle 100, by canceling the sideslip angle β of that vehicle,
An ideal steering angle can be obtained for stabilizing the vehicle behavior. Also, as shown in FIG. 5B, when the vehicle 100 does not skid, the vehicle 100 travels in a direction indicated by a broken line and in an understeer state in the front-rear direction of the skid vehicle 100.
The side slip angle of the vehicle formed by the vehicle center line indicated by the chain line is represented by β. Assuming that there is no side slip, the current steering angle of the vehicle 100 can be regarded as the actual steering angle δo immediately before the vehicle behavior is determined to be in an unstable state. Therefore,
If the actual steering angle δ at the present time is δ = δo−β, it means that the steering for canceling the side slip angle β of the vehicle has been performed. Since the traveling direction of the vehicle 100 when there is no side slip corresponds to the traveling direction of the center of gravity of the vehicle 100, by canceling the side slip angle β of the vehicle, the steering angle becomes an ideal steering angle for stabilizing the vehicle behavior. it can.

If the side slip angle β of the vehicle is not canceled in step 9, the steering actuator 2 is adjusted so that the side slip angle β of the vehicle is canceled, that is, the steering angle can be set to the target value δ ^*. Control (step 10). In the present embodiment, the side slip angle β of the vehicle determined based on the detected variable from the actual steering angle δo immediately before the vehicle behavior is determined to be in an unstable state in step 3.
Is subtracted to obtain the target steering angle δ ^* = δo−β. The steering actuator 2 is controlled such that a deviation obtained by subtracting the actual steering angle δ from the target steering angle δ ^* becomes zero.
As a result, the attitude of the vehicle is controlled by the steering actuator 2 so as to be stabilized when the vehicle behavior is unstable.

Thereafter, it is determined whether or not to end the control based on, for example, the on / off of a key switch for starting the engine of the vehicle (step 11). If not, the process returns to step 1.

According to the above configuration, when the vehicle behavior is unstable and the attitude control is being performed, the reaction force component corresponding to the steering angle deviation (δh′−δ) is subtracted from the operation reaction force. The fluctuation of the steering angle deviation (δh′−δ) due to the attitude control does not affect the operation reaction force. Further, when the vehicle behavior is not unstable, for example, when the wheel 4 is fitted into the rut, the steering angle deviation (δh′−δ) increases sharply, and the steering angle deviation (δh ′) increases.
Even if the calculated value of the operation reaction force including the reaction force component corresponding to -δ) increases, the operation reaction force generated by the reaction force actuator 19 does not exceed the maximum torque Tmax. Therefore, even when such a sharp increase in the steering angle deviation (δh′−δ) occurs, the correction steering for canceling the increase in the steering angle deviation (δh′−δ) by operating the steering wheel 1 is impeded. Never.

The present invention is not limited to the above embodiment. For example, the attitude control of the vehicle for stabilizing the behavior of the vehicle is not limited to the one performed only by the steering actuator 2, but a function of controlling the attitude of the vehicle by controlling the braking force and the driving force is added. The present invention can be applied to vehicles. The operating member is not limited to the steering wheel that is rotated, and a joystick, for example, can be used.

[0032]

According to the present invention, in a vehicle in which the steering angle is changed by operating an operation member that is not mechanically connected to the wheels, the vehicle attitude control for stabilizing the vehicle behavior is performed. Steering feeling can be prevented from lowering,
Further, when the vehicle behavior is stable, an operation reaction force corresponding to the deviation between the indicated steering angle corresponding to the operation amount of the operation member and the actual steering angle can be applied, and the attitude control of the vehicle is not executed. It is possible to provide a steering device in which steering for correcting a sudden change in the steering angle at the time is not hindered.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of a steering device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the steering device according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating the operation of the steering device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a relationship between a yaw rate and a lateral acceleration of a vehicle including the steering device according to the embodiment of the present invention.

FIGS. 5A and 5B are explanatory diagrams of an operation in an oversteer state, and FIGS. 5A and 5B are explanatory diagrams of an operation in an understeer state of the vehicle provided with the steering device according to the embodiment of the present invention; FIGS.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering actuator 4 wheel 11 angle sensor 13 potentiometer 14 speed sensor 15 lateral acceleration sensor 16 yaw rate sensor 19 reaction force actuator 20 steering system controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62D 137: 00 (72) Inventor Takashi Takamatsu 3-5-8 Minamisenba, Chuo-ku, Osaka City, Osaka Koyo Seiko In-house (72) Inventor Masaya Segawa 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka Koyo Seiko F-term (reference) 3D032 CC08 DA03 DA04 DA15 DA23 DA24 DA29 DA33 DA39 DA93 DC02 DC09 DC33 DC40 DD02 DD17 EA01 EB04 EB11 EB12 EC22 EC29 FF01 FF07 GG01

Claims (2)

[Claims] 1. A steering apparatus for a vehicle in which an actual steering angle can be changed by a steering actuator driven according to an operation amount of an operation member without mechanically connecting the operation member to wheels. A reaction force actuator for generating an operation reaction force of the above, a means for detecting an operation amount of the operation member, a means for detecting an actual steering angle of the wheel, and a command steering corresponding to the detected operation amount of the operation member Means for calculating a steering angle deviation obtained by subtracting the detected actual steering angle from the angle;
Means for calculating an operation reaction force including a reaction force component corresponding to the operation amount of the operation member and a reaction force component corresponding to the steering angle deviation, and controlling the reaction force actuator to generate an operation reaction force Possible means, means for determining whether the vehicle behavior is unstable, and means for controlling the attitude of the vehicle by at least the steering actuator so as to stabilize when the vehicle behavior is unstable. When the vehicle behavior is not unstable, the reaction force actuator is controlled so as to generate the calculated operation reaction force, and when the vehicle behavior is unstable, the steering reaction is calculated from the calculated operation reaction force. A steering apparatus for a vehicle, wherein the reaction force actuator is controlled to generate an operation reaction force obtained by subtracting a reaction force component corresponding to an angular deviation. And means for storing a predetermined maximum operation reaction force. If the vehicle operation is not unstable and the calculated operation reaction force exceeds the stored maximum operation reaction force, the calculated operation reaction force is calculated. The vehicle steering system according to claim 1, wherein the reaction force actuator is controlled so as to generate the maximum operation reaction force instead of the operation reaction force.