JPH11152055A - Steering device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the limitation of stabilization and control of vehicle behavior in prevention of instability of vehicle behavior in steering by outputting both control signals of the force required for steering and the vehicle braking force according to the steering dependency corresponding to the priority of steering to braking operation in a course change of vehicle. SOLUTION: As the variable having an influence on unstable vehicle behavior in steering, vehicle speed and steering torque are determined by a vehicle speed sensor 51 and a torque sensor 3, respectively, and steering angle change speed is also determined by a steering system controller 50 from the steering angle by a steering sensor 9. Further, rotating speed of each wheel 8 and friction coefficient between vehicle and road surface are determined by a wheel speed sensor 52 and a friction coefficient sensor 62, respectively. The controller 50 stores the relation between the variable and the necessity of prevention of instability of vehicle behavior, and judges the presence of the necessity of instability prevention from the determined variable before the vehicle behavior becomes unstable, and stores and controls the relation among the variable, the steering dependency, the force required for steering, and the braking force. Thus, the vehicle behavior can be stabilized by a driver's own steering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device associated with a vehicle braking system.

[0002]

2. Description of the Related Art When a vehicle spins or drifts due to excessive speed during a curve run or a driver's driving error, the vehicle can be steered according to the driver's intention. Disappears.

[0003] In order to prevent such unstable vehicle behavior such as drift and spin, techniques for controlling the braking force and the driving force of the vehicle have been developed.

However, such a conventional technique is intended to stabilize the vehicle behavior near the movement limit of the vehicle where the grip force is saturated. Near the movement limit, there is no margin in the grip force of the tire on the road surface, so there is a limit to the control of the vehicle behavior.

An object of the present invention is to provide a steering device that can solve the above-mentioned problem.

[0006]

SUMMARY OF THE INVENTION A vehicle steering apparatus according to the present invention has a steering dependence that corresponds to a priority of a steering operation with respect to a braking operation during a change of direction of a vehicle when preventing a vehicle behavior from becoming unstable during steering. Accordingly, a control signal of a force required for steering the vehicle and a control signal of a braking force of the vehicle are output. The present invention is based on the fact that the driver's steering dependence is affected by the instability of the vehicle behavior. By arranging the pylons P as shown in FIG. 4, a 3.5 m-wide running path was formed. The traveling path has a width such that only one vehicle 10 can travel, as indicated by a broken line arrow in the figure, and steering is required on the way to change the course. The distance that the course can be changed is set to 10 m. If the course change is delayed or the course change is too early, the vehicle 10 will collide with the pylon P. A running test of the vehicle 10 at a speed of 50 km / h was performed by a plurality of drivers on the running path. In order to create a situation where it is necessary to prevent the vehicle behavior from becoming unstable, a steering suppression force is applied so that the course cannot be changed during normal steering, and the steering is performed so rapidly that the vehicle behavior becomes unstable. The steering suppression force can be released only when the steering is stopped. FIGS. 5 and 6 show the results of the running test. In the figures, the mark △ indicates that the vehicle 10 can pass without falling down the pylon P, the mark ○ indicates that the vehicle 10 has stopped, This is the case where 10 collided. The horizontal axis in FIG. 5 is the maximum steering torque corresponding to the priority of the steering, and the vertical axis is the average deceleration corresponding to the priority of the braking operation. The horizontal axis in FIG. 6 is the maximum steering angle corresponding to the steering priority, and the vertical axis is the average deceleration corresponding to the braking operation priority. From this running test, the vehicle 10 has a tendency to collide with the pylon P as the steering priority for the braking operation at the time of changing the direction of the vehicle is higher, that is, as the driver's steering dependence increases. The lower the steering priority,
That is, it was confirmed that the vehicle 10 tends to stop as the driver's steering dependence decreases, and the vehicle 10 tends to pass without falling down the pylon P so that the braking operation and the steering are balanced. That is, when changing the direction of the vehicle, which of the steering and the braking operation is prioritized differs for each driver, and the higher the steering priority, the greater the steering dependency. For example, as the steering torque increases during the change of direction of the vehicle, the deceleration of the vehicle decreases, the depression force of the brake pedal decreases, and the delay of the braking operation start time from the steering start time increases, the steering dependence increases. Become. If the degree of operation dependence is too large or too small, the force required for steering the vehicle and the braking force of the vehicle become unbalanced, the vehicle behavior becomes unstable, and the vehicle attitude is controlled by the driver himself. You will not be able to do it. According to the configuration of the present invention, the force required for steering the vehicle and the braking force of the vehicle increase as the steering dependence increases, and the force required for steering the vehicle decreases as the steering dependence decreases. By reducing the braking force of
The balance between the force required for steering the vehicle and the braking force of the vehicle can be optimized. Thus, in a normal driving state before the vehicle reaches the motion limit, the driver's own steering can stabilize the vehicle behavior and improve safety.

Means for obtaining a parameter correlated with the steering dependency, means for storing a relationship between the parameter and the steering dependency, and means for calculating the steering dependency based on the obtained parameter and the stored relationship are provided. Preferably, it is provided. According to this configuration, the behavior of the vehicle can be stabilized according to the situation that changes every moment by calculating the degree of steering dependence based on the parameter. As parameters correlated with the steering dependence, the magnitude of the steering torque, the deceleration of the vehicle, the depression force of the brake pedal, the delay of the start of the brake operation with respect to the start of the steering, and the like can be obtained. The relationship between the parameter and the steering dependency may be determined so that the steering dependency can be obtained from the parameter by following the relationship.

It is preferable to provide a means for setting the steering dependence to an arbitrary value. According to this configuration, the vehicle behavior can be stabilized according to the characteristics of the driver by setting the steering dependence to an optimal value in advance.

In the steering apparatus according to the present invention, a means for determining a variable affecting the instability of the vehicle behavior during steering and a predetermined relationship between the variable and the necessity of preventing the vehicle behavior from being unstable are stored. Means, a means for determining the necessity of preventing the vehicle behavior from becoming unstable based on the obtained variable and the stored relationship, and the variable, the steering dependence, the force required for steering the vehicle, and the braking force of the vehicle. Means for storing the predetermined relationship of the above, and when it is necessary to prevent instability of the vehicle behavior, based on the obtained variable, the steering dependence and the stored relationship,
It is preferable to include a means for outputting a control signal of a force required for steering the vehicle and a control signal of a braking force of the vehicle. According to this configuration, it is possible to optimize the force required for steering and the braking force in accordance with the degree of dependence on steering, thereby stably stabilizing the vehicle behavior. As variables affecting the instability of the vehicle behavior during the steering, for example, a vehicle speed, a steering angle, a steering angle change speed, a steering torque, and the like can be obtained. Further, a friction coefficient between the vehicle and a road surface, a wheel rotation The speed, the yaw rate of the vehicle, the lateral acceleration acting on the vehicle, and the like may be determined together, and the accuracy of preventing the vehicle behavior from becoming unstable can be improved as more variables are determined. The relationship between the variable and the necessity of prevention of vehicle behavior instability can be determined by observing the relationship, from the obtained variable, the necessity of prevention of vehicle behavior instability can be determined, The determination may be made such that the determination can be made before the vehicle behavior becomes unstable. The relationship between the variable, the steering dependence, the force required to steer the vehicle, and the braking force of the vehicle is based on the relationship, and the force required for steering the vehicle and the vehicle control corresponding to the determined variable and the steering dependence are obtained. The power may be determined, and the vehicle behavior may be stabilized by controlling the force required for steering the vehicle and the braking force of the vehicle such that the determined value is obtained. .

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

A rack and pinion type electric power steering apparatus 1 for a vehicle shown in FIG. 1 has an input shaft 2 connected to a steering wheel H, and a torque sensor 3
And an output shaft 4 which is connected to the output shaft 4. The input shaft 2 and the output shaft 4 constitute a steering shaft that transmits torque applied for steering by a driver to wheels. Its output shaft 4 is a universal joint 5
And a wheel 8 is connected to a rack 7 that meshes with the pinion 6. When the steering torque is transmitted to the rack 7 via the steering wheel H, the input shaft 2, the torque sensor 3, the output shaft 4, and the pinion 6, the vehicle is steered by the movement of the rack 7.
A steering angle sensor 9 is attached to the input shaft 2. In this embodiment, the front wheels are steered, but the front and rear wheels may be steered.

A bevel gear 12 is fitted around the output shaft 4 and a bevel gear 15 meshing with the bevel gear 12 is provided.
Is rotationally driven by the actuator 13. Thereby, the actuator 13 generates a torque that is added to the torque applied by the driver.

A braking system is provided for braking each wheel 8 of the vehicle. That is, the brake pedal 16
The master cylinder 17 generates a braking pressure corresponding to the pedaling force of the vehicle. The braking pressure is amplified by the braking pressure control unit 18 and distributed to the brake devices 19 of the respective wheels 8, and the respective brake devices 19 apply a braking force to the respective wheels 8. The braking pressure control unit 18 is connected to a brake controller 60 constituted by a computer. A sensor 52 for individually detecting the rotational speed of each wheel 8 and a sensor 61 for individually detecting the braking force of each wheel 8 are connected to the brake system controller 60. The brake system controller 60 amplifies and distributes the braking pressure according to the rotation speed of each wheel 8 detected by the wheel speed sensor 52 and the feedback value from the braking force detection sensor 61. The control unit 18 is controlled so that the braking force of each wheel can be individually controlled.
The braking pressure control unit 18 is connected to the brake pedal 16.
Even when the operation described above is not performed, the built-in pump can generate the braking pressure.

The torque sensor 3 detects a torque transmitted from the input shaft 2 to the output shaft 4, that is, a steering torque transmitted by the steering shaft. The torque sensor 3 is connected to a steering system controller 50 constituted by a computer. The steering system controller 50 is connected with the steering angle sensor 9, the actuator 13, the vehicle speed sensor 51, the friction coefficient sensor 62 for detecting a friction coefficient between the vehicle and the road surface, and the brake system controller 60.

As variables affecting the instability of the vehicle behavior during steering, for example, the vehicle speed is obtained by the vehicle speed sensor 51, the steering angle is obtained by the steering angle sensor 9, and the steering torque is obtained by the torque sensor 3. The steering angle change speed is determined by the steering system controller 50 from the steering angle determined by the steering angle sensor 9, the rotation speed of each wheel 8 is determined by the wheel speed sensor 52, and the friction coefficient sensor 62 determines the distance between the vehicle and the road surface. Is determined.

The steering system controller 50 includes:
The relationship between the variable and the necessity of preventing the vehicle behavior from becoming unstable is stored. By observing the relationship between the variables and the need to prevent vehicle behavior instability, it is possible to judge the necessity of vehicle behavior instability prevention based on the obtained variables. The determination may be made such that the determination can be made before the vehicle behavior becomes unstable. This relationship can be determined by experiment. Based on the stored relationship and the obtained variable, the steering system controller 50 can determine the necessity of preventing the vehicle behavior from becoming unstable. For example, as shown in FIG. 2, the relationship between the tire slip angle and the cornering force is linear while the tire slip angle is small, but deviates from the linear relationship when the tire slip angle is large, so that the vehicle behavior becomes unstable. Therefore, the tire slip angle is obtained from the variable, and when the tire slip angle becomes equal to or larger than the set value, it is determined that it is necessary to prevent the vehicle behavior from becoming unstable. The relationship between the variable and the tire slip angle can be determined by experiments.

The parameters correlating to the steering dependence corresponding to the priority of the steering operation with respect to the braking operation when changing the direction of the vehicle include, for example, the steering torque, the deceleration of the vehicle, the depressing force of the brake pedal 16, the braking force with respect to the starting time of the steering. A delay at the start of the operation is required. The pedaling force of the brake pedal 16 is determined by the detection value of the braking pressure detection sensor 64, the steering start time is determined by the detection start time of the steering angle sensor 9, and the brake operation start time is determined by the detection start time of the braking pressure detection sensor 64. Can be.

The steering system controller 50 stores the relationship between the parameter and the steering dependency, and calculates the steering dependency based on the obtained parameter and the stored relationship. The greater the steering torque is, the smaller the deceleration of the vehicle is, the smaller the depressing force of the brake pedal 16 is, and the greater the delay between the start of the steering operation and the start of the brake operation is, the greater the steering dependence is.

The steering system controller 50 includes:
A predetermined relationship among the variables, the steering dependence, the force required for steering the vehicle, and the braking force of the vehicle is stored. The relationship between the variable, the steering dependence, the force required to steer the vehicle, and the braking force of the vehicle follows this relationship, and the force required to steer the vehicle and the vehicle control corresponding to the determined variable and the steering dependence are obtained. The power is determined, and by controlling the force required for steering the vehicle and the braking force of the vehicle such that the determined value is obtained, the behavior of the vehicle can be stabilized.
This relationship can be determined by experiment.

The steering system controller 50 includes:
An input device 7 for setting the steering dependence to an arbitrary value
0 is connected, and the steering dependence can be set to an arbitrary value by an input operation by the operator. The input device 70 can be constituted by, for example, a keyboard. The input value of the steering dependence is stored by the steering system controller 50. Also, the input device 7
From 0, the selection signal of the steering dependence can be input to the steering system controller 50 by the operation of the operator,
It is possible to select which of the value set by the input device 70 and the value automatically set by the calculation by the steering system controller 50 as described above as the steering dependence.

The steering system controller 50 includes:
Based on the obtained variables, the steering dependence, and the relationship between the stored variables, the steering dependence, the force required for steering the vehicle, and the braking force of the vehicle, the values were determined when it was necessary to prevent the vehicle behavior from becoming unstable. A vehicle steering force and a vehicle braking force corresponding to the variable and the steering dependence are obtained. The control signal of the force required for steering the vehicle is output to the actuator 13 so that the obtained value is obtained, and the control signal of the braking force of the vehicle is output to the brake controller 60. As a result, the actuator 13 is controlled so that the deviation between the detected steering torque and the torque corresponding to the required steering force becomes zero. The braking force detection sensor 61
Each braking device 19 is controlled so that the deviation between the braking force of each wheel 8 detected by the vehicle and the obtained braking force becomes zero.
Is controlled. By controlling the torque and the braking force applied by the actuator 13, the greater the steering dependence, the greater the force required for steering the vehicle and the greater the braking force of the vehicle. That is, the driving force of the actuator 13 is reduced. Further, the smaller the steering dependence, the smaller the force required for steering the vehicle and the smaller the braking force of the vehicle. That is, the driving force of the actuator 13 is increased. Thereby, the balance between the force required for steering the vehicle and the braking force of the vehicle is optimized.

FIG. 3 is a flowchart showing a control procedure of the above system. First, the steering system controller 50
The brake controller 60 reads the data detected by each of the sensors (step 1).

Next, as described above, based on the determined variable that affects the instability of the vehicle behavior during steering,
It is determined whether it is necessary to prevent the vehicle behavior from becoming unstable (step 2).

If it is not necessary to prevent the vehicle behavior from becoming unstable, the steering system controller 50 controls the actuator 13 to apply a normal steering assist force in accordance with the detected steering torque and vehicle speed (step 3). ).

If there is a need to prevent the vehicle behavior from becoming unstable in step 2, the input device determines whether or not to use a value automatically set by the steering system controller 50 as the steering dependence. The determination is made based on the selection signal input from 70 (step 4).

In step 4, when a value that is automatically set as the steering dependence is used, the steering dependence is calculated based on the parameters obtained as described above and the stored relationship, and the calculated value is used as the steering dependence. (Step 5).

In step 4, when the value automatically set as the steering dependency is not used, the value set as the steering dependency by the operator is read by the input device 70, and the value is set as the steering dependency (step 6). ).

After setting the steering dependence in step 5 or 6, the steering system controller 5
0, as described above, determines the force required for steering the vehicle and the braking force of the vehicle corresponding to the determined variable and the steering dependence, and determines the force required for steering the vehicle so as to reach the determined value. A control signal is output to the actuator 13, and a control signal of the braking force of the vehicle is output to the brake controller 60. Thereby, the vehicle stabilization control is performed by optimizing the balance between the force required for steering the vehicle and the braking force of the vehicle (step 7).

The above control is repeated until the engine of the vehicle stops (step 8).

According to the above configuration, the force required for steering the vehicle and the braking force of the vehicle increase as the steering dependence increases, and the force required for steering the vehicle and the vehicle braking force decrease as the steering dependence decreases. By reducing the braking force, the balance between the force required for steering the vehicle and the braking force of the vehicle can be optimized. Thus, in a normal driving state before the vehicle reaches the motion limit, the driver's own steering can smoothly stabilize the vehicle behavior and improve safety. By obtaining the degree of steering dependence based on the parameters, it is possible to stabilize the vehicle behavior according to the situation that changes every moment. Further, by setting the steering dependence to an optimal value in advance, the vehicle behavior can be stabilized according to the characteristics of the driver.

The present invention is not limited to the above embodiment. For example, the steering device is not limited to the rack and pinion type, but may be a ball screw type. Further, the actuator, the type of the speed reducer of the actuator, and the connection position of the actuator to the steering mechanism can be arbitrarily set.

[0032]

According to the present invention, by stabilizing the vehicle behavior smoothly by the driver's own steering, safety,
A steering device for a vehicle that can improve the steering feeling can be provided.

[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 diagram showing a relationship between a tire slip angle and a cornering force.

FIG. 3 is a flowchart showing a control procedure of the steering device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a running test of a vehicle.

FIG. 5 is a diagram showing the relationship between the maximum steering torque and the average deceleration indicating the results of a vehicle running test.

FIG. 6 is a diagram showing the relationship between the maximum steering angle and the average deceleration, showing the results of a vehicle running test.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 rack and pinion type electric power steering device 3 torque sensor 8 wheels 9 steering angle sensor 13 actuator (electric motor) 18 braking pressure control unit 19 brake device 50 steering system controller 51 vehicle speed sensor 52 wheel speed detection sensor 60 brake system controller 61 braking force Detection sensor 62 Friction coefficient sensor 64 Braking pressure detection sensor 70 Input device

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B62D 119: 00

Claims (4)

[Claims] 1. A control signal of a force required for steering a vehicle according to a steering dependence corresponding to a priority of a steering operation with respect to a braking operation during a change of direction of the vehicle when preventing the vehicle behavior from becoming unstable during steering. A vehicle steering device that outputs a control signal of a vehicle braking force. 2. A means for obtaining a parameter correlated with the steering dependency, a means for storing a relationship between the parameter and the steering dependency, and a means for calculating a steering dependency based on the obtained parameter and the stored relationship. The vehicle steering apparatus according to claim 1, comprising: 3. The vehicle steering apparatus according to claim 1, further comprising means for setting the degree of steering dependence to an arbitrary value. 4. A means for determining a variable affecting the destabilization of vehicle behavior during steering, means for storing a predetermined relationship between the variable and the need to prevent destabilization of vehicle behavior, Means for determining the necessity of preventing the vehicle behavior from becoming unstable based on the variables and the stored relationships, and a predetermined relationship between the variables, the steering dependence, the force required for steering the vehicle, and the braking force of the vehicle. And a control signal for controlling the force required for steering the vehicle and a control signal for controlling the braking force of the vehicle based on the determined variable, the steering dependence, and the stored relationship when the vehicle behavior is to be prevented from becoming unstable. A steering device for a vehicle according to any one of claims 1 to 3, further comprising: