JP2000351382A - Steering control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering control device for a vehicle to ensure transmission rigidity of a steering system as vibration of a steering handle is suppressed by a method wherein a control gain specifying a relation between a control deviation and a control amount is suitably set according to a steering state and a car speed. SOLUTION: A proportional gain P is set according to the magnitude of an angle deviation (e) forming a control deviation on a basis of a map of an S208. This constitution suppresses the generation of vibration as a result of the proportional gain P being set a low value during hand-off steering where the angle deviation (e) is decreased. When the angle deviation (e) is increased with the progress of steering, the proportional gain P is set to a high value and transmission rigidity of a steering system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering control device for controlling the steering of a vehicle, and more particularly to a variable transmission ratio mechanism for changing a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel. The present invention relates to a vehicle steering control device provided with:

[0002]

2. Description of the Related Art Conventionally, a steering control device equipped with a variable transmission ratio mechanism for changing a transmission ratio of a steering wheel to a steering angle of a steered wheel has been known. By driving the variable transmission ratio mechanism with an actuator, the transmission ratio between the input and output via the variable transmission ratio mechanism, that is, the transmission ratio between the steering angle of the steering wheel and the turning angle of the steered wheels changes. It has become. For example, in Japanese Patent Application Laid-Open No. H10-236328, the drive control of the actuator is performed so that the rotation angle of the output shaft in the variable transmission ratio mechanism matches the target rotation angle.

[0003]

The control amount for such an actuator is set in accordance with the control deviation between the actual rotation angle of the output shaft and the target rotation angle, and is independent of the steering state or running state. The control amount set correspondingly is always constant. Therefore, for example, if a control deviation occurs even during idling, the actuator is driven in accordance with the control deviation. There is a possibility that the handle vibrates along the circumferential direction.

Therefore, when the control gain is set to be low, the vibration of the steering wheel at low vehicle speed is suppressed, but at high vehicle speed, the dead zone is increased due to the setting of the transmission ratio to be slow, and the transmission of the steering system is increased. Rigidity decreases.

The present invention has been made to solve such a problem, and an object of the present invention is to appropriately set a control gain for defining a relationship between a control deviation and a control amount in accordance with a steering state, a vehicle speed, and the like. An object of the present invention is to provide a vehicle steering control device capable of ensuring the transmission rigidity of the steering system while suppressing the vibration of the steering wheel by setting.

[0006]

SUMMARY OF THE INVENTION Therefore, a vehicle steering control device according to a first aspect of the present invention is a vehicle steering control device for performing a vehicle steering control, and is driven by an actuator to control a steering angle and a turning angle of a steering wheel. A transmission ratio varying unit that changes a transmission ratio between the steering wheel and the steering wheel; and a control unit that performs drive control of the actuator. The control unit includes a transmission ratio set according to a traveling state of the vehicle and a steering ratio. Based on the state, target turning state setting means for setting a target turning state of the steered wheels, control gain setting means for setting a control gain,
Control amount setting means for setting a control amount for the actuator in accordance with a control deviation that is a difference between the target turning state and the actual turning state, and a control gain set by the control gain setting means. The control gain setting means sets the control gain to a small value in a region where the control deviation is small, and sets the control gain to a larger value in a region where the control deviation is large.

When the control deviation is small and the load is low, it is assumed that the steering wheel is held with a small steering torque, the hand is released from the steering wheel, and the like. Set a small value to suppress the occurrence of vibration at the steering wheel. In addition, when the load is high, in which the control deviation increases due to steering, the control gain is set to a large value to further improve the followability of the actuator and secure the transmission rigidity of the steering system.

According to a second aspect of the present invention, there is provided a vehicle steering control device comprising:
What is claimed is: 1. A vehicle steering control device for performing vehicle steering control, comprising: a transmission ratio variable unit driven by an actuator to change a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel; Control means for performing control, wherein the control means sets a target turning state of the steered wheels based on a transmission ratio and a steering state which are set according to a traveling state of the vehicle. Control gain setting means for setting a control gain; control deviation for a difference between a target turning state and an actual turning state; and control for the actuator according to a control gain set by the control gain setting means. Control gain setting means for setting the control gain, wherein the control gain setting means sets the control gain to a small value in a region where the vehicle speed is low, and sets the control gain to a larger value in a region where the vehicle speed is high. .

When the steering wheel is released in a situation where idling vibration is occurring, vibration of the steering wheel is likely to occur. For this reason, in a region where the vehicle speed is low, the control gain is set to a small value to suppress the occurrence of vibration at the steering wheel. In a region where the vehicle speed is high, the control gain is set to a larger value to increase the transmission rigidity of the steering system.

According to a third aspect of the present invention, there is provided a steering control device for a vehicle.
What is claimed is: 1. A vehicle steering control device for performing vehicle steering control, comprising: a transmission ratio variable unit driven by an actuator to change a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel; Control means for performing control, wherein the control means sets a target turning state of the steered wheels based on a transmission ratio and a steering state which are set according to a traveling state of the vehicle. A gain setting means for setting a control gain, a control deviation which is a difference between a target turning state and a turning state of a steered wheel, and a control amount for the actuator in accordance with the control gain set by the gain setting means. Control gain setting means for setting the control gain to a small value in a region where the steering speed is low, and setting the control gain to a larger value in a region where the steering speed is high. That.

In an emergency such as danger avoidance, sudden steering may be performed. Therefore, in a region where the steering speed is high, the control gain is set to a larger value to improve the followability and operability of the steered wheels. In a region where the steering speed is low, the control gain is set to a small value to suppress the occurrence of vibration at the steering wheel.

According to a fourth aspect of the present invention, there is provided a vehicle steering control device comprising:
In the vehicle steering control device according to claim 1, the target turning state is a target turning angle of the steered wheels, and the turning state is an actual turning angle of the steered wheels.

The control deviation is a position deviation between the target turning angle of the steered wheels and the actual turning angle of the steered wheels, and the control amount setting means sets the control amount for the actuator in accordance with the position deviation and the control gain. Is set.

According to a fifth aspect of the present invention, there is provided a vehicle steering control device comprising:
In the vehicle steering control device according to claim 1, the target turning state is a target turning speed of the steered wheels, and the turning state is an actual turning speed of the steered wheels.

The control deviation is the speed deviation between the target turning speed of the steered wheels and the actual turning speed of the steered wheels. The control amount setting means sets the control amount for the actuator in accordance with the speed deviation and the control gain. Is set. Thereby, for example, by adding the control amount set based on the speed deviation to the control amount set based on the position deviation, the responsiveness at the time of sudden steering is further improved, and Occurrence of vibration at the time is further suppressed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the accompanying drawings.

FIG. 1 shows a configuration of a vehicle steering control device according to an embodiment.

The input shaft 20 and the output shaft 40 are connected via a variable transmission ratio mechanism 30, and the steering handle 10 is connected to the input shaft 20. The output shaft 40 is connected to a rack shaft 51 via a rack and pinion type gear device 50, and steered wheels FW are provided on both sides of the rack shaft 51.
1, FW2 is connected.

The input shaft 20 is provided with an input angle sensor 21 for detecting an input angle θh serving as a steering angle of the steering wheel 10, and the output shaft 40 detects an output angle θp serving as a rotation angle of the output shaft 40. An output angle sensor 41 is provided. The rotation angle of the output shaft 40 corresponds to the stroke position of the rack shaft 51, and the stroke position of the rack shaft 51 is
In order to correspond to the turning angles of W1 and FW2, the output angle sensor 4
The turning angle of the steered wheels FW1 and FW2 is detected by detecting the rotation angle of the output shaft 40 according to 1.

The variable transmission ratio mechanism 30 includes a steering wheel 10.
A gear mechanism for connecting the input shaft 20 and the output shaft 40 and a motor 31 for driving the gear mechanism.
And The gear 31 is driven by the motor 31 to change the transmission ratio (input angle θh / output angle θp) at which the steering angle of the steering wheel 10 is transmitted as the steering angle of the steered wheels FW1, FW2. .

The drive control of the variable transmission ratio mechanism 30 is performed by a steering control device 70. The steering control device 70 includes an input angle sensor 21 provided on the input shaft 20, an output angle sensor 41 provided on the output shaft 40, and the vehicle. The drive control of the motor 31 in the transmission ratio variable mechanism 30 is performed by outputting a control signal Is to the motor 31 based on each detection signal of the vehicle speed sensor 71 for detecting the speed.

Here, the processing performed by the steering control device 70 will be described with reference to the flowchart of FIG.

This flowchart is started by turning on the ignition switch. First, the process proceeds to step (hereinafter, step is referred to as “S”) 102, where the input angle θh detected by the input angle sensor 21 and the output angle sensor 41
And the vehicle speed V detected by the vehicle speed sensor 71 are read.

In S104, a map is searched from the map showing the relationship between the vehicle speed V and the transmission ratio G shown in FIG. 3 based on the vehicle speed V read in S102, and the transmission ratio G according to the vehicle speed V is set. .

In the following S106, based on the input angle θh read in S102 and the transmission ratio G set in S104,
Calculate θpm = (1 / G) · θh to set the target output angle θpm of the output shaft 40 that constitutes the target turning state.

In S108, the target output angle θpm set in S106 and the output angle θ read in S102.
An angle deviation e from p is set as e = θpm−θp.

At S110, a differential gain P is set as a control gain corresponding to the angle deviation e set at S108.
Set. This setting process will be described later.

At S112, the output angular velocity dθp / dt is calculated based on the output angle θp read at S102 and the previous value θpold of the output angle θp (see S124).
The calculation is performed as dt = (θp−θpold) / Δt. “Δt” is a sampling time that is a time interval between the output angle θp and the previous value θpold. In addition, “Δt” used in an arithmetic expression described later uses the same value as this value.

At S114, the target output angle θpm set at S106 and the previous value θpmold of the target output angle θpm are set.
(See S124), the target output angular velocity dθpm
/ Dt, dθpm / dt = (θpm−θpmold) /
Calculate as Δt.

At S116, an angular velocity deviation ev which is a deviation between the output angular velocity dθp / dt set at S112 and the target output angular velocity dθpm / dt set at S114.
Is set as ev = dθpm / dt−dθp / dt.

At S118, a differential gain D is set as a control gain corresponding to the angular velocity deviation ev set at S116. This setting process will be described later.

At S120, the angle deviation e set at S108, the proportional gain P set at S110, and S116
The control signal Is for the motor 31 is calculated based on the angular velocity deviation ev set in step (1) and the differential gain D set in step S118.
It is determined as Is = P ・ e + D ・ ev.

At S122, the control signal Is determined at S120 is output to the motor 31, and the motor 31 is driven according to the control signal Is.

Then, in S124, the input angle θh read in S102 is set to θhold, the output angle θp is set to θpold,
The target output angle θpm set at 106 is defined as θpmold,
Each is set and this value is stored. Then, this result is read out in the next routine.

Thereafter, the program proceeds to S126, in which it is determined whether or not the ignition switch (IG) has been turned off.
In this case, the process returns to S102, and the above-described processes from S102 are repeatedly executed until “Yes” is determined in S126.

Here, the setting process of the proportional gain P executed in S110 is shown in the block diagram of FIG.

In S202, | e | is set by taking the absolute value of the angle deviation e set in S108. In S204, a correction value α1 corresponding to the vehicle speed V read in S102 is set based on the map shown in S204. S204
In the map shown in FIG. 7, in a low vehicle speed range up to the vehicle speed V1, the lower the vehicle speed V, the smaller the correction value α1 is set to a smaller value.
In the above, the correction value α1 is set to a certain large value.

In S206, the absolute value | e |
A total value ALL1 expressed as the sum of
ALL1 = | e | + α1 is set.

In S208, the proportional gain P corresponding to the total value ALL1 is determined based on the map shown in S208.
In step S210, the value searched in step S208 is set as the value of the proportional gain P.

In the map shown in S208, the total value AL
In an area smaller than L1th, the proportional gain P is set to a smaller value as the value of the total value ALL1 is smaller.
In the region above L1th, the proportional gain P is set to a certain large value.

Accordingly, assuming that the vehicle speed V is constant, the proportional gain P is set to a smaller value as the angular deviation | e | is smaller, and the proportional gain is set to a constant larger value in a region where the angular deviation | e | is larger. . Hereinafter, this operation will be described.

The situation where the angle deviation | e | is small is the situation where the steering wheel 10 is maintained with a small steering torque,
A situation where the hand is released from the steering wheel 10 is assumed. If the proportional gain P is set to a large value in such a situation, a phenomenon in which the steering wheel 10 vibrates in the circumferential direction is likely to occur. A situation where the angle deviation | e | is large is assumed to be a situation where the steering wheel 10 is largely steered by a large steering torque. In such a situation, the proportional gain P is set to a large value. Steering wheel FW
1. I want to improve the tracking and response of the FW2.

Therefore, in a region where the angle deviation | e | is large,
The proportional gain P is set to a large value to increase the transmission rigidity of the steering system at the time of steering, and the proportional gain P is set to a small value as the angular deviation | e | is small, thereby suppressing the generation of vibration in the steering wheel 10. I do.

Assuming that the angle deviation | e | is constant, the proportional gain P is set to a smaller value as the vehicle speed V decreases in a low vehicle speed range lower than the vehicle speed V1, and the proportional gain P becomes constant above the vehicle speed V1. Set to a large value. This operation will be described. When the steering wheel 10 is released in a situation where idling vibration is generated, the steering wheel 1 is released.
Vibration along the circumferential direction tends to occur at zero. Therefore, in a region where the vehicle speed V is low, the proportional gain P is set to a small value,
Generation of vibration in the steering wheel 10 is suppressed. Also,
In a region where the vehicle speed V is high, the transmission gain of the steering system is increased by setting the proportional gain P to a large value, and the road surface state and the like are transmitted to the steering wheel 10 side accurately.

It should be noted that in the block diagram of FIG.
L1 was determined as ALL1 = | e | + α1, but a correction value α2 corresponding to the steering speed dθh / dt was set based on the map shown in FIG. 5, and the total value ALL1 was set to ALL1 = |
e | + α1 + α2. Thus, the value of the proportional gain P can be set in consideration of any of the angle deviation, the vehicle speed, and the steering speed. In the map shown in FIG. 5, when the steering speed | dθh / dt | is equal to or higher than the middle speed indicated by “a”, the correction value α2 is maintained at a constant large value to increase the transmission rigidity of the steering system. Also, the steering speed |
In a low-speed range where dθh / dt | is smaller than “a”, the correction value α2 is set to a smaller value as the steering speed | dθh / dt | is lower, and the proportional gain P is set so that the vibration of the steering wheel 10 is suppressed. Set.

Next, the setting processing of the differential gain D executed in S118 is shown in the block diagram of FIG.

First, in S302, the input angle θh read in S102 and the previous value θhold of the input angle θh (S124
), The steering speed dθh / dt is calculated as dθh /
The calculation is performed as dt = (θh−θhold) / Δt. In subsequent S304, the steering speed dθh /
By taking the absolute value of dt, | dθh / dt | is set.

In S306, based on the map shown in S306, a correction value β corresponding to the vehicle speed V read in S102.
Set 1. In the map shown in S306, in a low vehicle speed range up to the vehicle speed V2, the correction value β1 is set to a smaller value as the vehicle speed V is lower, and the correction value β1 is set to a certain large value at a vehicle speed V2 or higher.

In S308, the steering speed | dθh / dt |
A total value ALL2 represented as a sum of a correction value β1 and
ALL2 = | dθh / dt | + β1.

At S310, the differential gain D corresponding to the total value ALL2 is obtained based on the map shown at S310.
In step S312, the value retrieved in step S310 is set as the value of the differential gain D.

In the map shown in S310, the total value AL
In an area smaller than L2th, the smaller the value of the total value ALL2 is, the smaller the value of the differential gain D is set.
In the region above L2th, the differential gain D is set to a constant large value.

Therefore, assuming that the vehicle speed V is constant, the smaller the steering speed | dθh / dt |, the smaller the differential gain D is set to, the lower the control sensitivity to the steering speed | dθh / dt | The generation of vibration at 10 is suppressed. When the steering speed | dθh / dt | is increased to some extent, the differential gain D is set to a constant large value, whereby the operability of the steered wheels FW1 and FW2 during emergency steering such as danger avoidance is improved, and the steering is performed. Ensure the transmission rigidity of the system.

If the steering speed | dθh / dt | is constant, the differential gain D is set to be small in a region where the vehicle speed V is low, so that the generation of vibration in the steering wheel 10 is suppressed. In a region where the vehicle speed V is high, the differential gain D is set to be large, and the road surface reaction force is accurately transmitted to the steering wheel 10 to improve the steering feeling.

In the block diagram of FIG. 6, the sum AL
L2 was obtained as ALL2 = | dθh / dt | + β1, and based on the map shown in FIG. 7, the angle deviation | e |
The correction value β2 is set according to the total value ALL2.
2 = | dθh / dt | + β1 + β2. Accordingly, in a situation where the steering torque acting on the steering wheel 10 is very small, the generation of the vibration in the steering wheel can be further suppressed.

[0055]

According to the first aspect of the present invention, the control gain is set to a small value in a region where the control deviation is small, and the control gain is set to a large value in a region where the control deviation is large. Since the control gain setting means is provided, it is possible to sufficiently suppress the occurrence of vibration when the steering wheel is released, and to increase the transmission rigidity of the steering system during steering when the control deviation is large, thereby giving a good steering feeling.

According to the vehicle steering control device of the second aspect, the control gain setting means for setting the control gain to a small value in a region where the vehicle speed is low and setting the control gain to a larger value in a region where the vehicle speed is high. As a result, vibration of the steering wheel due to idling vibration during stopping can be suppressed, and at high vehicle speeds, the transmission rigidity of the steering system is increased to accurately transmit road surface reaction force to the steering wheel, improving steering feeling at high speed driving Can be done.

According to the vehicle steering control device of the third aspect, the control gain is set to a small value in a region where the steering speed is low and to a larger value in a region where the steering speed is high. Since the means is provided, it is possible to suppress the vibration of the steering wheel at the time of minute steering and to improve the responsiveness of the steered wheels at the time of sudden steering such as danger avoidance.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a vehicle steering control device according to an embodiment.

FIG. 2 is a flowchart showing a process executed by the steering control device.

FIG. 3 is a map that defines a relationship between a vehicle speed V and a transmission ratio G;

FIG. 4 is a block diagram showing a setting process of a proportional gain P;

FIG. 5 is a map that defines a relationship between a steering speed | dθh / dt | and a correction value α2.

FIG. 6 is a block diagram illustrating a setting process of a differential gain D;

FIG. 7 is a map defining a relationship between an angle deviation | e | and a correction value β20.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Steering handle, 20 ... Input shaft, 30 ... Transmission ratio variable mechanism, 31 ... Motor (actuator), 40 ... Output shaft, 70 ... Steering control device.

Continued on the front page (72) Inventor Morihiro Matsuda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Masahiko Shindo 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Invention Person Ryoichi Katsumata 1 Toyota Town, Toyota City, Aichi Prefecture F-term in Toyota Motor Corporation (reference) 3D032 CC08 CC22 DA03 DA04 DA23 DB11 DC01 DC03 DD01 DD06 EA01 EB04 EB30 EC22 EC31 GG01

Claims (5)

[Claims] 1. A vehicle steering control device for performing vehicle steering control, comprising: a transmission ratio variable means driven by an actuator to change a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel. And control means for performing drive control of the actuator, the control means comprising: a target turning state of the steered wheels based on the transmission ratio and a steering state set according to a traveling state of the vehicle. A target turning state setting means for setting a control gain, a gain setting means for setting a control gain, a control deviation which is a difference between the target turning state and an actual turning state, and a control set by the gain setting means. Control amount setting means for setting a control amount for the actuator in accordance with a gain, wherein the control gain setting means sets the control gain to a small value in a region where the control deviation is small. The control deviation is a vehicle steering control device for setting the control gain to a larger value in a large area. 2. A steering control device for a vehicle that performs steering control of a vehicle, the transmission ratio varying means being driven by an actuator to change a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel. And control means for performing drive control of the actuator, the control means comprising: a target turning state of the steered wheels based on the transmission ratio and a steering state set according to a traveling state of the vehicle. A target turning state setting means for setting a control gain, a gain setting means for setting a control gain, a control deviation which is a difference between the target turning state and an actual turning state, and a control set by the gain setting means. Control amount setting means for setting a control amount for the actuator in accordance with a gain, wherein the control gain setting means sets the control gain to a small value in a region where the vehicle speed is low; The vehicle steering control apparatus for setting the control gain to a larger value in a high region. 3. A steering control device for a vehicle for performing steering control of a vehicle, the transmission ratio varying means being driven by an actuator to change a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel. And control means for performing drive control of the actuator, the control means comprising: a target turning state of the steered wheels based on the transmission ratio and a steering state set according to a traveling state of the vehicle. A target turning state setting means for setting a control gain; a gain setting means for setting a control gain; a control deviation which is a difference between the target turning state and a turning state of a steered wheel; and a control deviation set by the gain setting means. Control amount setting means for setting a control amount for the actuator according to the control gain, wherein the control gain setting means sets the control gain to a small value in a region where the steering speed is low. The steering speed is a vehicle steering control device for setting the control gain to a larger value in a high region. 4. The vehicle steering system according to claim 1, wherein the target steered state is a target steered angle of the steered wheels, and the steered state is an actual steered angle of the steered wheels. Control device. 5. The vehicle steering system according to claim 1, wherein the target turning state is a target turning speed of the steered wheels, and the turning state is an actual turning speed of the steered wheels. Control device.