JPS61205560A - Rear wheel steering controller for vehicle - Google Patents

Abstract

PURPOSE:To perform turning or course change under high speed travelling quickly and stably by deciding whether the steering wheel is operated quickly or slowly under high speed travelling and differentiating the steering angle between the front and rear wheels. CONSTITUTION:A microcomputor 26 is provided with a car speed signal from car speed sensor 24, a front wheel steering angle signal from steering angle sensor 25 and a front wheel steering speed signal from a differentiator 31. Then the car speed is compared with a predetermined speed to decide whether it is high speed travel or low speed travel. Upon decision of high speed travel, the front wheel steering speed is compared with a predetermined speed to decide whether it is steered for the purpose of turning or course change. Upon decision that it is steered for turning, the microcomputer 26 will set to the first steering angle ratio thus to function an actuator 19 and to position the fulcrum 18a of a rolling lever 18 to provide the first steering angle ratio. While upon decision that it is steered for course change, it is set to second steering angle ratio larger than the first steering angle ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vehicle equipped with a front wheel steering mechanism and a rear wheel steering mechanism. The present invention relates to a rear wheel steering control device for a vehicle that controls wheels in the same phase.

[Prior art]

Conventionally, this type of control device controls the turning angle of the rear wheels to be in phase with the turning angle of the front wheels when the vehicle is running at high speed to adjust the turning radius of the vehicle, as shown in Japanese Patent Application Laid-Open No. 59-81263. The idea is to make it larger.

With this configuration, it is possible to stably perform gentle turns and lane changes of high-speed vehicles.

[Problem that the invention seeks to solve]

However, in the conventional device described above, the ratio of the rear wheel steering angle to the front wheel steering angle (hereinafter simply referred to as steering angle ratio) is uniquely set according to the vehicle speed value, so this set steering angle ratio is If it is large, the turning radius of the vehicle becomes too large and the steering performance of the vehicle turning at high speed deteriorates. Furthermore, if the set steering angle ratio is small, the turning radius of the vehicle becomes small, making it difficult for a vehicle traveling at high speed to change lanes quickly and stably.

In order to solve the above problem, the present invention automatically distinguishes between steering for turning, in which the steering wheel is operated slowly, and steering for changing lanes, in which the steering wheel is operated quickly, while driving at high speed, and each type of steering is different. The present invention aims to provide a rear wheel steering control device for use in front and rear wheel steered vehicles, which allows a vehicle running at high speed to quickly and stably turn and change lanes by setting the angle ratio. .

[Means for solving problems]

In solving this problem, the structural features of the present invention, as shown in FIG. 1, include a front wheel steering mechanism 1 for steering the front wheels;
In a vehicle equipped with a rear wheel steering mechanism 2 that steers rear wheels in accordance with front wheel steering of the front wheel steering mechanism 1, a vehicle speed detection means 3 that detects vehicle speed and a front wheel steering mechanism that detects a front wheel steering angle are provided. a steering angle detecting means 4; a front wheel turning speed detecting means 5 for detecting a front wheel turning speed; and a control value for controlling the rear wheel turning angle to be in phase with the front wheel turning angle when the detected vehicle speed is high. When the front wheel steering angle is less than a predetermined angle, a first control value is calculated;
When the detected front wheel turning angle is larger than a predetermined angle and the detected front wheel turning speed is larger than a predetermined speed, a second control for controlling the rear wheel turning angle in the same phase direction as the front wheel turning angle compared with the first control value. A calculation means 6 that calculates the value, and a control signal representing the first control value or the second control value are transmitted to the rear wheel steering device trR2.
This is because an output means 7 is provided for controlling the rear wheel steering angle by outputting an output to the rear wheel steering angle.

[Effect]

In the present invention configured as described above, the front wheel steering angle detection means 4, the front wheel turning speed detection means 5, and the calculation means 6 set the steering angle ratio of the vehicle running at high speed to a small value when the front wheel steering angle is small. In addition, when the front wheel steering angle and front wheel steering speed are large, the steering angle ratio of the vehicle running at high speed is set to be large, so when the vehicle running at high speed turns, the steering angle ratio of the vehicle is small. This setting improves steering performance, and when the vehicle changes lanes, the steering angle ratio of the vehicle is set to a large value so that lane changes can be made quickly and stably.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Fig. 2 shows a front wheel steering mechanism A, a rear wheel steering mechanism B, and an electric control device C of the mechanism B of a vehicle to which the present invention is applicable. There is.

The front wheel steering mechanism A includes a pinion and rack mechanism 11 and a pair of left and right steering rod sections 12a and 12b connected to the rack section of the mechanism 11. The pinion and rack mechanism 11 is connected to a steering handle 14 via a steering shaft 13 at its pinion portion.
The rotational motion of the relay rod portions 12a and 12b is converted into reciprocating motion of the relay rod portions 12a and 12b. The left and right relay rods 12a and 12b are connected to left and right tie rods (not shown) and left and right knuckle arms 1.
It is connected to the left and right front wheels 16a and 16b via 5a and 15b, respectively, and steers the left and right front wheels 16a and 16b.

Rear wheel steering mechanism B includes a swing lever 18 for steering rear wheels 17a and 17b in conjunction with the steering of front wheels 16a and 16b, and a linear actuator 19 for displacing a movable fulcrum 18a of this swing lever 18. and left and right rear wheels 17a, 17b
It is equipped with a relay rod 20 that interlocks the. The swing lever 18 has a fixed point 18b to which a front connecting rod 21 connected to the knuckle arm 15a is pivoted, and a rear connecting rod 22.
When the movable fulcrum 18a is between the fixed points 18b and 18c, the fixed point 18c is rotated in the opposite direction to the fixed point 18b, and the movable fulcrum 1
When the fixed point 8a is on the opposite side of the fixed point 18b from the fixed point 18C, the fixed point 18c is rotated in the same direction as the fixed point 18b, and when the movable fulcrum 18a is on the fixed point 18C, the fixed point 1. 8c, move the movable fulcrum 1
The steering angle ratio is set depending on the position of 8a.

The linear actuator 19 includes an actuator loft 19a connected to a movable fulcrum 18a, and by moving the actuator loft 19a in the lateral direction of the vehicle body, the movable fulcrum 18a is moved in the same direction.

The relay iron 20 connects the left and right rear wheels 17a and 17b to left and right tie rods (not shown), left and right knuckle arms 23a,
The rear connecting rod 22 is connected to the left knuckle arm 23a, and the swing lever 18 swings the rear wheel 17a.

17b is being steered.

The electric control device C includes a vehicle speed sensor 24 that picks up the rotation of the output shaft of the transmission and generates a pickup signal with a frequency corresponding to the vehicle speed, and a vehicle speed sensor 24 that is attached to the steering shaft 13 and that detects the front wheels 16a.
, 16b and a front wheel steering angle sensor 25 that detects the front wheel steering angle and generates an analog signal indicating a voltage value corresponding to the front wheel steering angle, and the signals given from each of these sensors 24 and 25. A microcomputer 26 calculates a target steering angle ratio by executing a program to be described later based on the microcomputer 26, a differential amplifier 27 drives and controls the linear actuator 19, and detects the moving position of the linear actuator rod 19a, that is, the current position of the movable fulcrum 18a. and a position sensor 28 that generates an analog signal indicating a voltage value corresponding to the current steering angle ratio set by the swing lever 18.

The microcomputer 26 includes a read-only memory (ROM) 26a that stores a program corresponding to the flowchart shown in FIG. 3, a central processing unit (CPU) 26b that executes this program, and variables and flags necessary for this program. Writable memory for temporary storage
(RAM) 26c, an input/output interface (Ilo) 26d for exchanging data with an external circuit, a read-only memory 26a, a central processing unit 26b, a writable memory 26C, and an input/output interface 26d.
It consists of a bus 26e that commonly connects the two. The input/output interface 26d includes a waveform shaper 29 that converts the pickup signal from the vehicle speed sensor 24 into a rectangular wave signal and supplies the vehicle speed signal to the microcomputer 26.
An analog-to-digital converter (A/D converter) 30 converts the analog signal from the front wheel steering angle sensor 25 into a digital signal and supplies the front wheel steering angle data to the microcomputer 26; A differentiator 31 differentiates the wheel turning angle data and supplies front wheel turning speed data indicating the front wheel turning speed to the microcomputer 26, and converts the digital signal indicating the target steering angle ratio calculated by the microcomputer 26 into an analog signal. Convert to differential amplifier 27
A digital-to-analog converter (D/A converter) 32 is connected to the first input terminal 27a of the converter.

The differential amplifier 27 has a first input terminal 27a connected to the position sensor 28, and has a first input terminal 27a and a second input terminal 27b.
The actuator rod 19a is driven so as to displace the movable fulcrum i8a until both voltage values applied to the fulcrum i8a match. This allows the swing lever 18 to set the target steering angle ratio.

The operation of the rear wheel steering control device used in front and rear wheel steered vehicles configured as described above will be explained using the flowchart shown in FIG.

When the ignition switch is closed to start the vehicle, the microcomputer 26 starts executing the program at step 100, and resets the mode flag MFLG indicating the lane change state of the vehicle at step 101, that is, sets it to "0". do. After the above settings, the program goes to step l.

2. Proceeding to steps 103 and 104, the microcomputer 26 outputs the data from the vehicle speed sensor 24 to the waveform shaper 2 in step 102.
The vehicle speed U is calculated based on the vehicle speed signal supplied via 9, and the calculation result is stored in the writable memory 26c. A memory 26c that can read and write front wheel turning angle data indicating the front wheel turning angle δ.
In step 104, the front wheel turning speed data indicating the front wheel turning speed a supplied from the differentiator 31 is read and stored in the writable memory 26c.

Next, in step 105, the microcomputer 26 reads the vehicle speed U from the writable memory 26c and compares this vehicle speed U with a predetermined speed uo set between low and high speeds. When the vehicle is running at a low speed, the microcomputer 26 determines rNOJ, that is, the vehicle speed U, in step 105.
It is determined that the vehicle speed is not greater than the predetermined vehicle speed U0, and the program proceeds to step 106. After the microcomputer 26 sets the mode flag MFLG to '0'' in step 106, the steering knob 107 sets the target steering angle ratio K corresponding to the vehicle speed U to the steering angle ratio characteristic shown by the solid line in FIG. This characteristic graph shows 1 for the first steering angle that controls the rear wheels from opposite phase to the front wheels as the vehicle speed increases, and when the vehicle speed is high, this first steering angle 1 for rudder angle ratio
is a value smaller than 2 for the second steering angle ratio described later. next,
The program proceeds to step 108, and in step 108, the microcomputer 26 outputs digital data indicating the target steering angle ratio K set to 1 as the first steering angle ratio to the digital-to-analog converter 32. This digital data is converted by the digital-to-analog converter 32 into an analog signal indicating a voltage value corresponding to the target steering angle ratio K, and is supplied to the first input terminal 27a of the differential amplifier 27. Since the differential amplifier 27 is supplied with an analog signal indicating a voltage value corresponding to the current steering angle ratio from the position sensor 28 to its second input terminal 27b, it controls the linear actuator 19 to adjust the current steering angle ratio to the target. The movable fulcrum 18a of the swing lever 18 is displaced until it matches the steering angle ratio. With the swing lever 18 setting the rear wheels 17a, 17b to the target steering angle ratio, when the front wheels 16a, 16b are steered, this steering force is applied to the left knuckle arm 15a, the front connecting rod 21. Swing lever 18° rear connecting rod 22, left knuckle arm 23a.

The signal is transmitted to the relay rod 20 and the right knuckle arm 23b, and the rear wheels 17a, 17b are steered to the target steering angle ratio K.

After the calculation in step 108 as described above, the microcomputer 26 returns to execute the calculation in step 102 again.
Step 102, until the vehicle speed U exceeds the predetermined vehicle speed uO.
The circular operations of 103, 104°, 105, 106, 107, and 108 are continued. In the above-described cyclic calculation, since the vehicle speed U is small and the target steering angle ratio is set to be negative, the rear wheels are controlled in the opposite phase to the front wheels, allowing the vehicle to turn in a small radius.

Above steps 102, 103, 104, 105゜106
．． During the cyclic calculation of 107 and 108, the vehicle speed U is the predetermined vehicle speed uO
If it becomes larger, the microcomputer 26 determines that it is rYEsJ in step 105, and in step 10
At step 9, the front wheel turning speed a is compared with a predetermined speed aO. This predetermined speed ao is set to a value slightly larger than 1 radian per second for normal turning, and is used to distinguish between turning and lane changing in a high-speed vehicle. If the vehicle has not changed lanes, the microcomputer 26 executes step 10.
At 9, rNOJ, that is, the front wheel turning speed a reaches the predetermined speed aO.
The program then proceeds to step 110 after determining that it is not larger than
Proceed to. At step 110, the microcomputer 26
determines whether the mode flag MFLG is "0" or not. Since this mode flag MFLG was set to "0" at step 106 during the above-mentioned cyclic calculation, the microcomputer 26 determines rYESJ at step 110, and the program proceeds to step 106. Then, the microcomputer 26 sets the mode flag MFLG to "O" in step 106, sets the target steering angle ratio K to the first steering angle ratio Kl in step 107, and sets the target steering angle ratio K to the first steering angle ratio Kl in step 108. The rear wheel steering mechanism B is set to the target steering angle ratio K by outputting digital data corresponding to the target steering angle ratio K. After setting the target steering angle ratio, the program returns to step 102, and the microcomputer 26 executes steps 102, 103, and 104.
, 105, 109, 110, 106°107.108 circular operations are executed. Through this circular calculation, the steering angle ratio is
Since the first steering angle ratio shown by the solid line in the figure is set to 1,
Even if the vehicle speed increases, the rear wheel steering angle is controlled to be in phase with the front wheel steering angle and to a small value, thereby stabilizing the straight running and cornering of the vehicle.

Above steps 102, 103, 104, 105゜109
．． During the cyclic calculation of steps 110, 106, 107, and 108, when the vehicle starts to change lanes, the front wheel steering speed a becomes larger than the predetermined speed ao, and the microcomputer 26 performs step 1.
In 09, it is judged as rYEsJ and the program goes to step 1.
Proceed to step 11. When the vehicle is changing lanes, the front wheel turning angle δ becomes larger than the small predetermined angle δO, so the microcomputer 26 determines rYEsJ at step 111, moves to step 112, and changes the mode to step 112. The flag MFLG is set to 1". Setting of this mode flag MFLG means that the vehicle is in a lane change state. After setting the mode flag MFLG, the program proceeds to step 113, and in step 113, the microcomputer 26 The target steering angle ratio K corresponding to the vehicle speed U is calculated based on the steering angle ratio characteristic graph shown by the broken line in FIG. 2 indicates the second steering angle ratio that is controlled to be in phase with the vehicle speed U.
It is defined only when it is larger than o, and the first steering angle ratio is a value larger than 1.

Next, the program proceeds to step 108, and in step 108, the microcomputer 26 sets the rear wheel steering mechanism B to the target steering angle ratio K, which indicates 2 as the second steering angle ratio. After setting the target steering angle ratio, the program goes to step 1.
Returning to step 02, the microcomputer 26 returns to step 102.
,103,104゜105.109,111,112,
113 and 108 cyclic operations are performed. During this cyclic calculation, if the rotational operation of the steering wheel 14 is stopped and the front wheel turning speed a becomes less than the predetermined speed ao, the microcomputer 26 proceeds to step 109 [determined as NOJ and proceeds to step 110]. Execute the calculation. Step 11
0, the microcomputer 26 selects rNOJ because the mode flag MFLG is set to "1'" at this time.
After determining this, the program proceeds to step 111. When the vehicle is changing lanes, the front wheel steering speed a is the predetermined speed a.
Even if the angle is less than 0, the steering wheel 14 remains rotated and the front wheel turning angle δ is maintained larger than the predetermined angle δ0, so the microcomputer 26 executes step 11.
1 is determined to be rYESJ, and steps 112, 113,
108,102,103゜104.105,109,1
10,111 cyclic operations will be performed. Steps 102, 103, 104, 105, 1 as above
09°111.112,113,108 or step 1
02, 103. 104. 105. 109. 1
The steering angle ratio during the cyclic calculation of 10°111.112, 113, and 108 is set to 2, which is the second steering angle ratio shown by the broken line in Fig. 4, so the rear wheel steering angle is different from the front wheel steering angle. Control is performed to have the same phase and a large value, allowing the vehicle to change lanes quickly and easily.

Furthermore, the above steps 102, 103, 104°105.
During the cyclic calculation of 109, 110, 111, 112, 113.108, when the lane change of the vehicle is completed, the steering wheel 1
4 is returned, the front wheel steering angle δ becomes smaller than the predetermined angle δ0, and the microcomputer 26 returns to step 111.
It is determined that the result is rNOJ, and the program proceeds to step 106. In step 106, the microcomputer 26 executes “
The mode flag MFLG, which had been set to 1'', is set to 0, and steps 106, 107, 108゜102.1
03, 104, 105, 109, and 110 are executed, and the steering angle ratio is again set to the first target steering angle ratio Kl.

In the embodiment j, the front wheel turning speed is obtained by differentiating the front wheel turning angle data with the differentiator 31 connected to the analog-to-digital converter 30, but the program of the microcomputer 26 may be changed. It is also possible to calculate the front wheel turning speed a by differentiating the front wheel turning angle δ using a program inside the microcomputer 26.

Next, to explain another embodiment of the present invention, FIG. 5 shows part of a rear wheel steering mechanism B and an electric control device C which are a modification of FIG. 2. Parts in between are omitted, and the same parts are given the same reference numerals. The rear wheel steering mechanism B includes left and right relay rods 20a that interlock left and right rear wheels 17a and 17b.

A linear actuator 33 is provided to directly drive the actuator 20b. The left and right relay rod parts 20a and 20b include left and right tie rods (not shown), left and right knuckle arms 23a,
Rear wheel 17a via 23b.

17b, and steers the rear wheels 17a and 17b in conjunction with each other. The electric control device C includes a position sensor 34 that detects the movement position of the right relay rod 20b and generates an analog signal indicating a voltage value corresponding to the current rearward steering angle, and a differential amplifier 35 that drives and controls the linear actuator 33. ing. The differential amplifier 35 has its first input terminal 35a inputted with an analog signal indicating a voltage value corresponding to the target rear wheel turning angle, and this analog signal and its second input terminal 35b are supplied from the position sensor 34. The linear actuator 33 is controlled according to the voltage difference with the analog signal. Note that the remaining parts of the front wheel steering mechanism A and the electric control device C are the same as those shown in FIG.

In the case of this modification, the analog signal supplied to the first input terminal 35a of the differential amplifier 35 corresponds to the target rear wheel turning angle, and this target rear wheel turning angle is shown in FIG. is output at step 108 of the flowchart. That is, the program executed by the microcomputer 26 is partially changed, and in step 108 the microcomputer 26 reads out the front wheel steering angle δ stored in step 103 and calculates this front wheel steering angle δ and the target steering angle ratio K. The multiplication result is outputted to the digital-to-analog converter 32 as a target rear wheel turning angle. The remaining operations of this other embodiment are the same as those of the previous embodiment. As described above, according to this other embodiment, the swing lever 18, front wheels 16a, 16b, rear wheels 17a, 17b, etc.
There is no need for a mechanism to connect the two.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to the configuration of the invention described in the claims, FIG. 2 is a schematic diagram of a vehicle showing the first embodiment of the invention, and FIG. 3 is a diagram showing the operation of the microcomputer shown in FIG. FIG. 4 is a characteristic graph showing the steering angle ratio with respect to vehicle speed, and FIG. 5 is a schematic diagram showing a second embodiment of the present invention. Explanation of symbols 11...Pinion and rack mechanism, 12a. 12b, 20, 20a, 20b--Relay o7, 1
4... Steering handle, 16a, 16b... Front wheel, 1
7a, 17b... Rear wheel, 18... Rocking lever, 19
．． 33... Linear actuator, 21... Front connecting rod, 22... Rear side connecting rod, 24... Vehicle speed sensor, 25... Front wheel steering angle sensor, 26... Microcomputer, 27. 35... Differential amplifier, 28
゜33...position sensor, 31...differentiator. Applicant Toyota Motor Corporation Representative Patent Attorney Teru Hase - Figure 3 Figure 4 Figure 4 T-No I5 Proceeding Amendment (Voluntary) 1 Death April 19, 1960 1, Indication of Case 11m 60 Years Patent Application No. 45637 lrg entrance
Year No. 2,
Name of the invention: Dual-use rear wheel steering control device 3, relationship with the case of the person making the amendment Patent Applicant Address Name (Name) (320) Yota Motor Co., Ltd. Ryoshin Building Telephone Nagoya <052>583-1261 No. 6, drawings subject to correction. 7. Contents of correction The three beams in the drawing will be corrected as shown in the attached sheet. 8. List of attached documents

Claims (1)

[Claims] In a vehicle equipped with a front wheel steering mechanism that steers a front wheel, and a rear wheel steering mechanism that steers a rear wheel in accordance with the front wheel steering of the front wheel steering mechanism, a vehicle speed detection means that detects a vehicle speed; Front wheel turning angle detection means for detecting a wheel turning angle; Front wheel turning speed detecting means for detecting a front wheel turning speed; and when the detected vehicle speed is high, the rear wheel turning angle is controlled to be in phase with the front wheel turning angle. A first control value is calculated as a control value when the detected front wheel turning angle is less than a predetermined angle, and a first control value is calculated when the detected front wheel turning angle is larger than a predetermined angle and the detected front wheel turning speed is larger than a predetermined speed. computing means for calculating a second control value for controlling the rear wheel steering angle in the same phase direction as the front wheel steering angle in comparison with the control value; 1. A rear wheel steering control device for a vehicle, comprising: an output means for controlling a rear wheel steering angle by outputting the output to a mechanism.