JPH05105055A - Travel controller at braking - Google Patents

Abstract

PURPOSE:To control both symmetrical wheels so as to make them brakeable at the shortest distance independently even in a split road surface as well as to prevent any unwilling yaw moment in a vehicle from occurring too. CONSTITUTION:A vehicle is provided with a target yaw rate operational means 90 calculating a target yaw rate for doing an optimum behavior in the vehicle, from a steering angle and a car speed, a real yaw rate measuring means measuring a real yaw rate of the vehicle, a yaw rate deviation operational means operating a deviation between the target yaw rate and the real yaw rate, two wheel steering gears 100, 21 regulating the steering angle of a wheel (a front wheel or rear wheel) so as to bring this yaw rate deviation into zero, and two antiskid devices 70, 40 regulating the braking force of each wheel of both symmetrical ones in an independent manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device for shortening the braking distance of a vehicle and ensuring steering stability during braking, and can be applied to a vehicle having a brake.

[0002]

2. Description of the Related Art Conventionally, an anti-skid device has been developed for adjusting a wheel slip ratio to shorten a braking distance. In the anti-skid device disclosed in Japanese Unexamined Patent Publication No. 61-244649, at least two control modes corresponding to high and low friction coefficients are preset in order to shorten the braking distance regardless of the friction coefficient of the road surface. The depressurization time T1 is measured, and the brake pressure is controlled in a mode applied to a low friction coefficient road surface when T1 is long and in a mode applied to a high friction coefficient road surface when T1 is short.

Here, when the left and right wheels are traveling on a road surface having a low friction coefficient (low μ), one wheel (for example, right wheel)
Becomes a high μ road surface, and the other wheel (left wheel)
When the vehicle runs on a low μ road surface as it is, the pressure of the right wheel brake is increased, the braking force of the right wheel is increased, the traveling direction of the vehicle is deflected to the right, and the steerability of the vehicle is impaired. In order to deal with this, it is detected that the friction coefficient of the road surface on which the left and right wheels are traveling is different, it is recognized that it is a split road surface, and the braking force of the wheel on the high μ side is detected when traveling on the split road surface. A technique for suppressing a drop and a yaw moment generated in a vehicle has been developed and is disclosed in Japanese Patent Application Laid-Open No. 1-249558.

Further, when the generation of the yaw moment is suppressed as described above, the braking force of one wheel is reduced, so that the braking distance is extended. Therefore, the braking distance is short, and
It is required to suppress the generation of yaw moment.
Japanese Patent Application Laid-Open No. 02-254051 discloses that when traveling on a split road surface during braking, the normal control and the control based on the vehicle speed are switched depending on the locking tendency of the wheels on the high μ side. Techniques for controlling wheels are disclosed,
The balance between ensuring steerability and shortening the braking distance.

[0005]

However, in the prior art, in any case, on a split road surface, high μ
The braking force on the road surface side must be reduced, and the braking distance becomes longer than when braking is performed on a road surface having a uniform friction coefficient for both wheels.

In view of the above, it is an object of the present invention to control the left and right wheels independently on the split road surface so that the braking can be performed at the shortest distance, and to suppress the undesired yaw moment of the vehicle.

[0007]

Means used in the present invention for solving the above-mentioned problems include a target yaw rate calculating means for calculating a target yaw rate for optimal behavior of a vehicle from a steering angle and a vehicle speed. An actual yaw rate measuring means for measuring an actual yaw rate of the vehicle, a yaw rate deviation calculating means for calculating a deviation between the target yaw rate and the actual yaw rate, and a wheel steering device for adjusting a steering angle of a wheel so that the yaw rate deviation becomes zero. The vehicle is provided with an anti-skid device that adjusts the braking force of the left and right wheels independently.

[0008]

According to the above means, even if the friction coefficient of the road surface is different between the left and right wheels during braking, the braking force is adjusted independently for each wheel to reduce the braking distance. Here, when the friction coefficients of the road surfaces of the left and right wheels are different, the vehicle tries to deflect. Therefore, a yaw moment is generated in the vehicle. The actual yaw rate measuring means measures the actual yaw rate of the vehicle generated by this yaw moment. on the other hand,
The target yaw rate calculation means calculates the yaw rate for performing the optimum behavior of the vehicle, and uses this as the target yaw rate. In the wheel steering system, the steering angle of the wheels is adjusted so that the deviation between the target yaw rate and the actual yaw rate becomes zero. Therefore, the steering of the vehicle will behave optimally. Therefore, the vehicle can be steered according to the steering of the driver and the braking distance can be minimized.

[0009]

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

FIG. 1 shows a block diagram of a first embodiment of the present invention. A brake device having wheel cylinders 14 to 17 is attached to each of the front right wheel 10, the front left wheel 11, the rear right wheel 12, and the rear left wheel 13. The wheels are braked by supplying hydraulic pressure to the wheel cylinders 14 to 17.
The hydraulic circuit 40 is connected to the wheel cylinders 14 to 17 via pipes 28 to 31. The hydraulic circuit 40 changes the master cylinder 27 according to the amount of depression of the brake pedal 26.
At the same time as supplying the hydraulic pressure generated at the wheel cylinder to the wheel cylinder, the hydraulic pressure is adjusted according to an instruction from the anti-skid control device 70. The hydraulic circuit 40 and the antiskid control device 70 constitute an antiskid device.

A front wheel steering rod 18 is connected to the front right wheel 10 and the front left wheel 11 as described above.
The front wheels are steered in accordance with the lateral movement of 8. The front wheel steering rod 18 is connected to the front wheel steering device 20. The front wheel steering device 20 laterally moves the front wheel steering rod 18 according to the rotation of the steering wheel 22. Therefore, the steering wheel 22 can be steered by rotating the steering wheel 22 to change the angle of the front wheels. A power steering mechanism may be added to the front wheel steering device 20.

A rear wheel steering rod 19 is connected to the rear right wheel 12 and the rear left wheel 13, and the rear wheel steering rod 1 is connected to the rear wheel steering rod 1.
The rear wheels are steered in accordance with the lateral movement of 9. The rear wheel steering rod 19 is connected to a rear wheel steering device 21. The rear wheel steering device 21 laterally moves the rear wheel steering rod 19 in response to an instruction from the rear wheel steering control device 100. The rear wheel steering device 21 and the rear wheel steering control device 100 constitute a wheel steering device.

The vehicle is provided with an arithmetic unit 90 for processing information common to a plurality of control devices mounted on the vehicle. The anti-skid control device 70 and the rear wheel steering control device 100 exchange information with the arithmetic unit 90.

A plurality of sensors are provided on the vehicle. The yaw rate sensor 23 measures the actual yaw rate γ generated in the vehicle and sends the information to the antiskid controller 70. The front wheel steering angle sensor 24 measures the rotation angle of the steering wheel 22 and sends information to the arithmetic unit 90 as a front wheel steering angle amount δf. The rear wheel steering angle sensor 25 is used for the rear wheel steering rod 1.
The moving amount of 9 is measured, and information is sent to the rear wheel steering control device 100 as the rear wheel steering angle amount δr. In addition, various sensors are mounted on the vehicle.

FIG. 2 is a control block diagram of this embodiment.
The anti-skid control device 70 is provided on each wheel in addition to the yaw rate sensor 23 described above, and a wheel speed sensor 34 for measuring the rotational speed of the wheel, and an acceleration for measuring the lateral and longitudinal accelerations of the vehicle. A brake switch 36 for detecting depression of the sensor 35 and the brake pedal 26 is connected. In addition, a motor 43 described later
a and the solenoid valves 52 to 59 are controlled. The anti-skid control device 70 internally calculates the maximum vehicle body speed VS1 and sends the maximum vehicle body speed VS1 information to the arithmetic unit 90. Further, information on the measured actual yaw rate amount γ is used as the rear wheel steering control device 10
Send to 0. Arithmetic unit 90 calculates a target yaw rate amount gamma ^*, and sends the target yaw rate amount gamma ^* to the anti-skid control unit 70 and the rear wheel steering control device 100.

Next, an anti-skid device for performing anti-skid control will be described. FIG. 3 shows a hydraulic circuit of the antiskid device. This hydraulic circuit is almost the same as the hydraulic circuit of the conventional anti-skid circuit. The two pipes 32 and 33 are connected to the master cylinder 27. The pipe 33 is connected to the pipe 28 via the pressure increasing solenoid valve 52 and the check valve 44, the pipe 28 is connected to the wheel cylinder 14 of the front right wheel 10, and is connected to the drain 51 via the pressure reducing solenoid valve 56. ing. Further, the pipe 33 is connected to the pipe 31 via the pressure increasing solenoid valve 55 and the check valve 47, the pipe 31 is connected to the wheel cylinder 17 of the rear left wheel 13, and is connected to the drain 51 via the pressure reducing solenoid valve 59. Has been done. The pipe 32 is connected to the pipe 29 via the pressure increasing solenoid valve 52 and the check valve 45, the pipe 29 is connected to the wheel cylinder 15 of the front left wheel 11, and the drain 50 is connected via the pressure reducing solenoid valve 57. There is. Further, the pipe 32 is connected to the pipe 30 via the pressure increasing solenoid valve 54 and the check valve 46, the pipe 30 is connected to the wheel cylinder 16 of the rear right wheel 12, and is connected to the drain 50 via the pressure reducing solenoid valve 58. It is connected. Each check valve returns the hydraulic pressure to the pipe 32 or 33 when the internal pressure of each wheel cylinder becomes higher than the pressure in the pipe 32 or 33, and functions to prevent the brake from being overly effective. Solenoid valves 52, 53 for increasing pressure,
54 and 55 communicate with the passage in a normal state, and switch to a state where the passage is closed by energization.

Further, the pressure reducing solenoid valves 56, 57, 58 and 59 close the passage in a normal state and switch to a state where the passage is opened by energization. Therefore, when the solenoid valves are not energized, the pipe 32 and the pipes 29 and 30 are in communication with each other, and the pipe 33 and the pipes 28 and 31 are in communication with each other. When the brake pedal 26 is depressed, the master cylinder 27 increases the hydraulic pressure in the pipes 32 and 33. This increase in pressure is transmitted to the wheel cylinder of each wheel via the check valve, and brakes the rotation of each wheel 10-13. Therefore, in the state where each solenoid valve is not energized, the braking force works according to the degree of depression of the brake pedal 26.

An output end of a pump 43 is connected to the pipes 32 and 33. As described above, the pipe 32 or 33 is connected to the wheel cylinder when the solenoid valves are not energized. When the motor 43a connected to the pump 43 is driven, the pressure in each wheel cylinder can be increased through each pipe. By driving the pump 43, even if the pressure in each wheel cylinder is once released while the brake pedal 26 is being depressed, the pressure in the wheel cylinder can be increased again. Here, when the pressure increasing solenoid valve 52 and the pressure reducing solenoid valve 56 are driven, the pressure increasing solenoid valve 52 is closed, the pressure reducing solenoid valve 56 is opened, and the oil in the wheel cylinder 14 is discharged to the drain 51. Therefore, by driving the solenoid valves 52 and 56, the pressure in the wheel cylinder 14 of the front right wheel can be weakened. The same applies to the other wheels, and by driving the respective pairs of solenoid valves 53 and 57, solenoid valves 54 and 58, and solenoid valves 55 and 59, the wheel cylinders of the front left wheel, the rear right wheel, and the rear left wheel, respectively. The pressure inside the tank can be weakened. As described above, the braking force of each wheel can be adjusted by controlling the energization of the pump and each solenoid valve and adjusting the pressure in the wheel cylinder. The motor 43a for driving the pump 43 and each electromagnetic valve are driven by the anti-skid control device 70. Check valves 48 and 49 are connected between the pipes 32 and 33 and the drains 50 and 51. The check valves 48 and 49 serve to return the hydraulic pressure of the drain to the pipes 32 and 33 when the pressure of the drain increases.

Sensors 60 to 63 are provided on the respective wheels. This sensor detects the state of each wheel and sends the detected information to the anti-skid controller 70. As shown in the block diagram of FIG. 2, in the embodiment of the present invention, the sensor mounted on each wheel is the wheel speed sensor 34 as described above. The wheel speed sensor 34 is a sensor for detecting the rotation speed of each wheel, and outputs a pulse-shaped wheel speed signal SP according to the rotation speed of the wheel for each wheel.
The anti-skid control device 70 receives a signal from the sensor and drives the motor 43a and the solenoid valves 52 to 59 according to the control shown by the block diagram of FIG.

As shown in FIG. 4, the anti-skid control device 70 includes a wheel speed / acceleration / estimated speed calculation unit 71, a control start / end determination unit 72, a motor control unit 73, a maximum vehicle body speed calculation unit 74, and a subtraction unit. 75, integrating unit 76, maximum deceleration calculating unit 77, target slip ratio calculating unit 78, slip ratio component calculating unit 79, G component calculating unit 80, control mode setting unit 81
And a solenoid valve control unit 82. Wheel speed / acceleration /
The estimated speed calculation unit 71 calculates the rotation speed and acceleration of the wheels of each wheel and the speed of the vehicle body. The control start / end determination unit 72 determines whether or not to perform the anti-skid control and whether or not to end it. The motor control unit 73 controls the rotation of the motor to generate hydraulic pressure in response to the execution of the anti-skid control. The maximum vehicle body speed calculation unit 74 calculates the maximum vehicle body speed VS1. The maximum deceleration calculation unit 77 calculates the maximum deceleration G. The target slip ratio calculator 78 calculates the target slip ratio of the wheels. The slip ratio component calculator 79 and the G component calculator 80 calculate a slip ratio component and an acceleration component for setting the control mode. The control mode setting unit 81 determines the control mode of each wheel from the slip ratio component and the acceleration component. The solenoid valve control unit 82 operates the solenoid valve of each wheel according to the obtained control mode, controls the pressure increase / decrease of the wheel cylinder, and adjusts the slip state of the wheel. Each of the above control units includes a maximum vehicle speed calculation unit 74, a maximum deceleration calculation unit 77, and a control start / end determination unit 7.
The control is independently performed on each of the front right wheel, the front left wheel, the rear right wheel, and the rear left wheel except for the motor control unit 73 and the motor control unit 73.

The details of each control unit will be described below.

In the wheel speed / acceleration / estimated speed calculation unit 71, the wheel acceleration DVW of each wheel, the wheel speed VW of each wheel, and the estimated vehicle body speed VS0 of each wheel are calculated as the wheel speed sensor 34 of each wheel.
It is calculated from the wheel speed signal SP from. Wheel acceleration DVW
Is the rotational acceleration of the wheels.

The wheel speed VW is the rotational speed of the wheel. The estimated vehicle speed VS0 is the speed of the vehicle body at the position where the wheel is attached. The wheel speed VW is obtained from the cycle and the wheel diameter by measuring the cycle of the pulsed wheel speed signal SP. The wheel acceleration DVW is obtained by differentiating the wheel speed VW. The estimated vehicle speed VS0 is obtained from the wheel speed VW in consideration of the turning state of the vehicle.

In the control start / end judging section 72, the brake output BK of the brake switch 36 and the estimated vehicle body speed VS0.
Also, the control start and end of the control is determined by receiving the control mode of each wheel described later. When the brake switch is on and the estimated vehicle body speed VS0 is within a predetermined value, it is determined whether control is started. Further, it is determined that the control ends when the pressure increasing mode ends for each wheel.

The motor control unit 56 receives a signal from the control start / end determination unit 72, rotates the motor 43a with the control start determination, and rotates the motor 43a with the control end determination.
Stop 3a.

The maximum vehicle body speed calculator 74 sets the maximum value of the estimated vehicle body speed VS0 of each wheel as the maximum vehicle body speed VS1. The maximum vehicle speed VS1 obtained is the rear wheel steering control device 1
Sent to 00.

The subtraction unit 75 obtains a yaw rate deviation Δγ which is a deviation between the target yaw rate amount γ ^* obtained from the arithmetic unit 90 and the actual yaw rate amount γ measured by the yaw rate sensor 23. In the integrating unit 76, the absolute value of the maximum vehicle body speed VS1 and the yaw rate deviation Δγ obtained are integrated to obtain a value | Δγ | · VS1.

The maximum deceleration calculation unit 77 receives the acceleration GX in the front-rear direction and the acceleration GY in the left-right direction and obtains the maximum deceleration G by the equation (1).

[0029]

[Equation 1]

The target slip ratio calculator 78 calculates the value | Δγ |
-Receive VS1 and the maximum deceleration G, and calculate a target slip ratio. Details of the target slip ratio calculator 78 are shown in FIG.

The acceleration G calculated by the maximum deceleration calculation unit 77 is given to the ΔG calculation unit 83, and the previous acceleration value G
By subtracting t−1, the acceleration increment ΔG can be obtained.

The ΔS calculator 84 obtains the slip ratio increase ΔS from the acceleration increase ΔG based on the graph shown in FIG. This target slip ratio S01 is obtained by adding the slip ratio increase ΔS and the target slip ratio S0t-1 obtained last time.

The slip ratio limiting unit 86 obtains the gain α from the value | Δγ | · VS1 based on the graph shown in FIG. 8 and multiplies the target slip ratio S01 by the gain α to obtain the target slip ratio S0. The target slip ratio S0 decreases as the maximum vehicle body speed VS1 increases and as the absolute value of the yaw rate deviation Δγ increases. Therefore, when the steering of the driver and the actual turning state of the vehicle match, control is performed so that the aforementioned slip ratio becomes maximum, and when the steering of the driver and the actual turning of the vehicle deviate from each other. The target slip ratio is controlled to be lowered in order to increase the cornering force.

In the above process, when the deceleration increases with time, ΔG has a positive value and ΔS also has a positive value, so the target slip ratio increases. Therefore, the slip amount of the wheels increases and the deceleration of the vehicle is suppressed. Further, when the deceleration decreases with time, ΔG becomes a negative value and ΔS also becomes a negative value, so the target slip ratio decreases. Therefore, the slip amount of the wheels is reduced and the deceleration of the vehicle is increased.

Therefore, if the above processing is continued, the deceleration becomes the maximum value. The relationship between deceleration and slip ratio is shown in Fig. 6.
Since it is known that there is a maximum value at one point as shown by solid lines A and B, the maximum value is the maximum value of deceleration. That is, the above process is a process in which the slip ratio that maximizes the deceleration is set as the target slip ratio, except for the slip ratio limiting unit 86. On a normal road surface, μ becomes maximum when the slip ratio is about 10 to 20% as indicated by the solid line A. There is a proportional relationship between μ and deceleration.
Therefore, if the slip ratio is controlled so as to be 10 to 20%, the braking distance when the brake is applied becomes the shortest on a normal road surface. However, there is a road surface condition where the braking distance is shorter when the wheels are locked, such as a gravel road. In this case, the relationship between the slip ratio and μ is maximized when the slip ratio is 100% as shown by the solid line B. In the above control, the deceleration is controlled to be maximum even on such a road surface. By performing this control, the deceleration becomes maximum on any road surface having μ, so that the shortest braking distance can be obtained regardless of μ on the road surface.

In the above processing, the acceleration measured by the acceleration sensor is controlled to be maximum. However, a value obtained by differentiating each wheel body speed VS0 may be used as an acceleration value instead of the acceleration measured by the acceleration sensor. Further, μ between the road surface and the wheel is the acceleration G and the load F.
Can be obtained from Therefore, the same result can be obtained by obtaining μ of each wheel from the load and acceleration and controlling so that the obtained μ becomes maximum. When the load changes for each wheel, it is preferable to perform control in consideration of the load.

Returning to FIG. 4, the description will be continued. The obtained target slip ratio is sent to the slip ratio component calculator 79. The slip ratio component calculator 79 calculates the slip ratio component DINDXS based on the equation (2).

[0038]

[Equation 2]

IVW is an integral value of the wheel speed VW. In this equation, (VS0-VW) / VS0 is the actual slip ratio. The slip ratio component DINDXS is sent to the control mode setting unit 81. Slip rate component DINDXS
Is basically a value obtained by subtracting the actual slip ratio from the target slip ratio S0 and is corrected, and represents the slip ratio deviation.

The G component calculator 80 subtracts the predetermined value G0 from the wheel acceleration DVW to obtain the G component DXNDDXG. G
The component DINDXG is sent to the control mode setting unit 81.

The control mode setting unit 81 receives the slip ratio component DINDXS and the G component DINDXG and sets the control mode. There are three control modes, pulse increase, pulse decrease, and sudden decrease. As described above, when the pressure increasing electromagnetic valves 52 to 55 are opened, the wheel cylinder is increased in pressure to increase the braking force, and when the pressure reducing electromagnetic valves 56 to 59 are opened, the wheel cylinder is reduced in pressure and the braking force is decreased. In the pulse pressure increasing mode, the pressure reducing solenoid valve is closed and the pressure increasing solenoid valve is duty-controlled to adjust the pressure. The braking force is controlled to be increased by adjusting the period and the pressure increasing time that is the time for opening the pressure increasing electromagnetic valve. In the pulse pressure reducing mode, the pressure increasing solenoid valve is closed and the pressure reducing solenoid valve is duty-controlled to adjust the pressure reduction. The braking force is controlled to be reduced by adjusting the cycle and the decompression time that is the time for opening the decompression solenoid valve. In the rapid decrease mode, the pressure increasing solenoid valve is closed and the pressure reducing solenoid valve is opened to rapidly reduce the wheel cylinder internal pressure. The control mode setting unit 81 sets these control modes and, at the same time, sets the pressure increasing time and cycle in the pressure increasing mode and the pressure decreasing time and period in the pressure decreasing mode according to a predetermined map. The setting of each mode is performed according to the map shown in FIG. Basically, this map is set so that as the slip ratio increases, the pulse increases, then decreases, then decreases sharply, and as the acceleration decreases, it increases, decreases, and decreases rapidly. ing. That is, when the G component is zero, the slip ratio deviation between the target slip ratio and the actual slip ratio is slightly increased when the pulse is zero, and the pulse decrease and the sudden decrease are performed as the slip ratio deviation increases. In this state, a map is set up so that when the deceleration G is large, the pulse is increased, and when the deceleration G is small, the pulse is decreased. Therefore, the braking force is adjusted in the direction in which the actual slip ratio matches the target slip ratio, and as a result, the actual slip ratio matches the target slip ratio. Since this adjustment is finely adjusted according to the acceleration, control can be performed quickly. The pressure increasing time, the pressure decreasing time, and the cycle are set according to the same map.

The solenoid valve control unit 82 controls the solenoid valves 52 to 59 according to the mode, pressure increase time, pressure decrease time and cycle set by the control mode setting unit 81. In the pulse increasing mode, the pressure reducing solenoid valve is closed, the pressure increasing solenoid valve is opened for the pressure increasing time, the pressure increasing solenoid valve is closed for the remaining period of time, and thereafter, the pressure increasing solenoid valve is repeatedly opened and closed. In the pulse reduction mode, the pressure increasing solenoid valve is closed, the pressure reducing solenoid valve is opened for the pressure reducing time, the pressure reducing solenoid valve is closed for the rest of the cycle, and then the pressure reducing solenoid valve is repeatedly opened and closed. In the sudden decrease mode, the solenoid valve for pressure increase is closed and the solenoid valve for pressure reduction is opened.

The target yaw rate amount γ ^* used in the above-mentioned anti-skid controller 70 is calculated by the arithmetic unit 9
Calculated at 0. The arithmetic unit 90 receives the maximum vehicle body speed VS1 from the anti-skid control device 70, and
The front wheel steering angle δf is received from the front wheel steering angle sensor 24. Next, in the target yaw rate calculation unit 91, the maximum vehicle speed VS
1 and the steering angle δf, the target yaw rate γ ^*
To get

[0044]

[Equation 3]

The obtained target yaw rate γ ^* is used not only by the antiskid controller 70 but also by the rear wheel steering controller 100.
Also sent to. The details of the rear wheel steering control device 100 are shown in FIG.
2 shows. The subtraction unit 101 subtracts the target yaw rate γ ^* from the actual yaw rate γ received from the anti-skid control device 70 to obtain the yaw rate deviation Δγ. Next, a dead zone is given to the yaw rate deviation Δγ by the limiter 102. Then, the subtraction unit 103 subtracts the rear wheel steering angle value δr from the yaw rate deviation to obtain a control amount, and the motor control unit 104 according to this control amount causes the motor 1 disclosed in FIG.
11 is driven.

FIG. 11 shows a rear wheel steering device 21. In the figure,
The motor 111 rotates the pinion 112. The pinion 112 meshes with the rack 113. Therefore,
The rack 113 can be moved laterally by rotating the pinion 112. The rack 113 is fixed to the rear wheel steering rod 19. Rear wheel steering rod 19
The rear wheels 12 and 13 are steered by the lateral movement of the.

In the above embodiment, the rear wheels 12 and 1
3 is steered by the rear wheel steering device 21 and the rear wheel steering control device 100 so that the actual yaw rate matches the target yaw rate. The target yaw rate is calculated by multiplying the front wheel steering angle δf by the gain G _A in the arithmetic unit 90 and calculating the maximum vehicle speed V
It is obtained by adding the correction by S1. Therefore, when the vehicle tries to rotate in a direction different from the steering direction of the vehicle intended by the driver while the vehicle is traveling, the rear wheels are steered so as to cancel the rotation. Therefore, even if an unexpected yaw moment occurs in the vehicle when the anti-skid device independently controls each wheel, this yaw is adjusted by the rear wheel steering device side, and the anti-skid side does not respond. May be.

Normally, when the friction coefficient of the road surface is uniform between the left and right wheels, and when the front wheels are steered as shown in FIG. 13A, yaw occurs as indicated by the solid arrow. However, when driving on a split road where the right side of the vehicle is low μ and the left side is high μ as shown in FIG. (B), if the four wheels are uniformly braked, Since the braking distance of the wheels becomes long, the yaw increases as shown by the solid arrow in FIG.
In the first embodiment, in order to suppress the occurrence of this unexpected yaw, the rear wheels are steered and the yaw is corrected in the direction desired by the driver as indicated by the solid arrow in FIG. This allows
The anti-skid control device can control each wheel so that the braking distance becomes the shortest.

In the first embodiment, the slip ratio limiting unit 86 shown in FIG. 5 limits the slip ratio according to the yaw rate deviation and the maximum vehicle speed. However, this does not work sufficiently. It is provided as a backup in case yaw occurs. The limit of the force generated by the tire is that, when the load is Fz, the vector sum of the lateral force and the longitudinal force is limited by μ · Fz. Therefore, even if the performance of the rear wheel steering system is high, the lateral force generated is limited. Since the limit is small during braking, it is necessary to weaken the braking force and generate a lateral force if necessary.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a front wheel steering control device 140 and a front wheel steering device 120 are used instead of the rear wheel steering control device 100 and the rear wheel steering device 21 of the first embodiment. Front wheel steering device 120 and front wheel steering control device 140
A wheel steering device is configured by the above. Arithmetic unit 90
The configurations of the antiskid control device 70, the antiskid hydraulic circuit 40, and the like are the same as those in the first embodiment, and the same members are designated by the same reference numerals. The arithmetic unit 90
In the first embodiment, the front wheel steering angle δf is directly received from the front wheel steering angle sensor 24, but in the second embodiment, it is obtained via the front wheel steering control device 140 as shown in FIG.

The structure of the front wheel steering system 120 of the second embodiment is shown in FIG. A pinion 123 is fixed to the tip of the shaft of the steering wheel 22. The pinion 123 meshes with the rack 124. The rack 24 has an extension 122.
A fluid cylinder 125 is fixed to the extending portion 122. The steering rods 18 of the front wheels 10 and 11 communicate with the inside of the fluid cylinder 125. The fluid cylinder 125 receives hydraulic pressure from the hydraulic control unit 121. The front wheel control device 140 controls the hydraulic pressure control unit 121 to adjust the hydraulic pressure applied to the fluid cylinder 125.

FIG. 17 shows details of the hydraulic control unit 121.
A piston 130 is fixed to the front wheel steering rod 18, and divides the space inside the fluid cylinder 125 into a first chamber 131 and a second chamber 132. First chamber 131 and second
Springs 133 and 134 for biasing the piston 130 toward the center are provided in the chamber 132, respectively. The solenoid valve 129 is driven by the front wheel steering control device 140 and connects the first chamber 133 and the pump 126 and the second chamber 132 and the drain 128, or connects the second chamber 134 and the pump 126 and the first chamber 131 and the drain 128. Or whether to block communication in either case. As a result, the pressure difference inside the first chamber 131 and the second chamber 132 is changed, and the piston 130 is moved in the left-right direction. 1
An accumulator 27 stores the pressure generated by the pump 126.

In the above structure, when the steering 22 is rotated when the piston is in the neutral position, the rack 12 is rotated.
4 moves to the left and right, and the front wheel steering rod 1
8 moves to the left and right, and the front wheels are steered. Here, if a pressure difference is provided between the first chamber 131 and the second chamber 132 of the fluid cylinder 125, the front wheel steering rod 18 further moves in the left-right direction with respect to the movement of the rack 124. Therefore, by driving the solenoid valve 129 in response to the driver's steering operation, the front wheels can be further rotated and returned.

As shown in FIG. 18, the front wheel steering control device 140 includes a subtracting unit 141, a limiter 142, and a subtracting unit 143.
And a solenoid valve control unit 144. The subtraction unit 141 subtracts the target yaw rate γ ^* from the actual yaw rate γ received from the anti-skid control device 70 to obtain a yaw rate deviation Δγ.
To get Next, the limiter 14 is added to the yaw rate deviation Δγ.
2 gives a dead zone. Then, the subtraction unit 143 subtracts the front wheel steering angle value δf from the yaw rate deviation to obtain a control amount, and the solenoid valve control unit 144 drives the solenoid valve 129 disclosed in FIG. 17 according to this control amount. Therefore,
The steering angle of the front wheels is corrected with respect to the steering by the steering so that the target yaw rate γ ^* is obtained.

In the above embodiment, the front wheels 10 and 1
Reference numeral 1 denotes a front wheel steering device 120 and a front wheel steering control device 140.
Thus, the actual yaw rate is steered so as to match the target yaw rate. The target yaw rate is obtained in the arithmetic unit 90 by multiplying the front wheel steering angle δf by the gain G _A and correcting the maximum vehicle speed VS1. Therefore, when the vehicle tries to rotate in a direction different from the steering direction of the vehicle intended by the driver while the vehicle is traveling, the front wheels are steered so as to cancel the rotation. Therefore, even if an unexpected yaw moment occurs in the vehicle when the anti-skid device independently controls each wheel, this yaw is adjusted by the front-wheel steering device side, and the anti-skid side does not have to deal with it. Good.

Normally, when the friction coefficient of the road surface is uniform on both the left and right wheels, and when the front wheels are steered as shown in FIG. 19 (A), yaw occurs as shown by the solid arrow. However, when driving on a split road where the right side of the vehicle is low μ and the left side is high μ as shown in FIG. (B), if the four wheels are uniformly braked, Since the braking distance of the wheels becomes long, the yaw increases as shown by the solid arrow in FIG.
In the second embodiment, in order to suppress the occurrence of this unexpected yaw, the steering amount of the front wheels is corrected, and the yaw is corrected in the direction desired by the driver as indicated by the solid arrow in FIG. 13 (C). As a result, the anti-skid control device can control each wheel so that the braking distance becomes the shortest.

In the above-mentioned first and second embodiments, the configuration of the electronic control unit is represented by a block diagram. However, it is determined whether it is configured by software using a microcomputer or hardware by combining circuit elements. Either may be used.

In the first and second embodiments, the arithmetic unit 90 is provided independently of the front wheel steering control device, the rear wheel steering control device and the anti-skid control device, but it may be built in each control device. I don't care.

In the above embodiment, in order to further shorten the braking distance during braking, the target slip ratio in anti-skid control was determined so as to maximize μ and deceleration. The rate may be set to a predetermined value given in advance.

In the first embodiment, the steering angle of the wheels is adjusted so that the yaw rate deviation is zero by steering the rear wheels, and in the second embodiment, the steering angle of the wheels is adjusted so that the yaw rate deviation is zero by steering the front wheels. did. Further, a front wheel steering device and a rear wheel steering device may be mounted on the vehicle so that both the front wheels and the rear wheels are adjusted at the same time.

In the above, the front wheel steering control device and the rear wheel steering control device adjust the steering angle of the wheels so that the yaw rate deviation becomes zero. However, the antiskid control device is operating from the antiskid control device. Receiving the information that there is such information, the yaw rate deviation is controlled to zero when the anti-skid control device is operating, and when the anti-skid control device is not operating, for example, Japanese Patent Laid-Open No. 60-12.
Other controls such as adjusting the rear wheels to a steering angle according to the vehicle speed and the steering angle as disclosed in Japanese Patent No. 4572 may be performed.

Further, in the first embodiment, the rear wheels are steered by using the motor.
Hydraulic pressure control may be performed as disclosed in Japanese Patent Publication No.
Similarly, in the second embodiment, the hydraulic circuit is used for the front wheel steering correction. However, for example, as disclosed in Japanese Patent Laid-Open No. 2-70561, a motor is used, or the steering and front wheel steering angles are by-wire. Many modifications are possible such as forming.

[0063]

According to the present invention, the vehicle can be steered according to the steering of the driver and the braking distance can be minimized.
Therefore, in order to avoid danger during sudden braking, the vehicle follows the steering well even if the steering is turned, and the braking distance does not become long.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a control block diagram of the first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram of an anti-skid hydraulic circuit according to the first embodiment of the present invention.

FIG. 4 is a block diagram of the anti-skid control device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a target slip ratio calculation unit according to the first embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the anti-skid control device according to the first embodiment of the present invention.

FIG. 7 is a graph showing the operation of the ΔS calculation unit according to the first embodiment of the present invention.

FIG. 8 is a graph showing the operation of the slip ratio limiting unit according to the first embodiment of the present invention.

FIG. 9 is a graph showing the operation of the control mode setting unit according to the first embodiment of the present invention.

FIG. 10 is a block diagram of an arithmetic unit according to the first embodiment of the present invention.

FIG. 11 is a configuration diagram of a rear wheel steering system according to a first embodiment of the present invention.

FIG. 12 is a block diagram of a rear wheel steering control device according to a first embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 14 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 15 is a control block diagram of a second embodiment of the present invention.

FIG. 16 is a configuration diagram of a front wheel steering system according to a second embodiment of the present invention.

FIG. 17 is a hydraulic circuit diagram of the front wheel steering system according to the second embodiment of the present invention.

FIG. 18 is a block diagram of a front wheel steering control device according to a second embodiment of the present invention.

FIG. 19 is an operation explanatory diagram of the second embodiment of the present invention.

[Explanation of symbols]

10 front right wheel 11 front left wheel 12 rear right wheel 1
3 Rear Left Wheel 14 to 17 Wheel Cylinder 18 Front Wheel Steering Rod 19 Rear Wheel Steering Rod 20 Front Wheel Steering Device 21 Rear Wheel Steering Device 22 Steering 23 Yaw Rate Sensor 24 Front Wheel Steering Angle Sensor 25 Rear Wheel Steering Angle Sensor 26 Brake Pedal 27 Master Cylinder 28 to 33 piping 34 wheel speed sensor 35 acceleration sensor 36 brake switch 40 hydraulic circuit 43 pump 43a motor 44-49 check valve 50, 51 drain 52-59 solenoid valve 60-63 sensor 70 anti-skid control device 71 wheel speed / acceleration / estimation Speed calculation unit 72 Control start / end determination unit 73 Motor control unit 74 Maximum vehicle speed calculation unit 75 Subtraction unit 76 Integration unit 77 Maximum deceleration calculation unit 78 Target slip ratio calculation unit 79 Slip ratio component calculation unit 80 G component calculation unit 81 Control mode Setting unit 82 Solenoid valve control unit 83 ΔG calculation unit 84 ΔS calculation unit 85 Addition unit 86 Slip ratio limiting unit 90 Calculation unit 91 Target yaw rate calculation unit 100 Rear wheel steering control device 101, 103 Subtraction unit 102 Limiter 104 Motor control unit 111 Motor 112 Pinion 113 Rack 120 Front Wheel Steering Device 121 Hydraulic Control Unit 122 Extending Part 123 Pinion 124 Rack 125 Fluid Cylinder 126 Pump 127 Accumulator 128 Drain 129 Solenoid Valve 130 Piston 131 First Chamber 132 Second Chamber 133, 134 Spring 140 Front Wheel Steering Control Device 141 Subtraction unit 142 Limiter 143 Subtraction unit 144 Solenoid valve control unit BK Brake output DINDXS Slip ratio component DXNDDXG G component DVW Wheel acceleration VW Wheel speed G Maximum deceleration GX longitudinal acceleration GY
Acceleration in the left-right direction G0 Predetermined value IVW Integral value of wheel speed VW S0, S01 Target slip rate SP Wheel speed signal VS0 Estimated vehicle speed VS1 Maximum vehicle speed ΔG Increase in acceleration ΔS Increase in slip rate Δγ Yaw rate deviation α Gain γ Actual yaw rate γ ^* Target yaw rate amount δf Front wheel steering angle amount δr Rear wheel steering angle amount

Claims (1)

[Claims] 1. A target yaw rate calculating means for calculating a target yaw rate for optimal behavior of the vehicle from a steering angle and a vehicle speed, an actual yaw rate measuring means for measuring an actual yaw rate of the vehicle, and the target yaw rate and the actual yaw rate. Braking means including a yaw rate deviation calculation means for calculating the deviation of the wheel, a wheel steering device for adjusting the steering angle of the wheels so as to make the yaw rate deviation zero, and an anti-skid device for adjusting the braking force of the wheels independently for the left and right wheels. Time traveling control device.