JPH07223552A - Rear wheel steering angle controller for vehicle - Google Patents

Abstract

PURPOSE:To carry out the return to the rear wheel steering angle control by the sure following to the traveling locus when the advance/retreat of a vehicle is judged from the state where the advance/retreat of the vehicle is indistinct, by securing the small turning function through the following to the desired traveling locus, even if the indistinct state for the advance/retreat of the vehicle is included during traveling, as for a rear wheel steering angle controller through the following to the traveling locus which improves the small turning performance in the low car speed region. CONSTITUTION:The first constitution consists of a target rear wheel steering angle value calculation part 13 in the ordinary traveling which has a vehicle stop judgement part f1 and an advance/retreat judgement part f2 and calculates the target rear wheel steering angle value based on the traveling locus of the vehicle in the case where advance or retreat is judged, and a locus following type target rear wheel steering angle value calculation suspending part 14 which suspends the calculation of the target rear wheel steering angle value based on the traveling locus of the vehicle in the case where it is judged that the advance/retreat of the vehicle is not distinct. The sound constitution is equipped with an initial set part f5 for initiallizing the target rear wheel steering angle value calculation part f3 in the ordinary traveling in the case where the change to advance or retreat from the indistinct state for advance and retreat is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering angle control device for a vehicle, and more particularly to a rear wheel steering angle control device which follows a traveling locus to improve a small turning performance in a low vehicle speed range.

[0002]

2. Description of the Related Art Conventionally, as a rear wheel rudder angle control device for improving a small turning performance in a low vehicle speed range, for example, Japanese Patent Laid-Open No. 2-74
The one described in Japanese Patent No. 473 is known.

In the above-mentioned conventional publication, the front end point of the vehicle calculated from the identified vehicle model in the controller by the front wheel steering angle signal detected by the front wheel steering angle detection means and the distance signal detected by the vehicle speed sensor. A technique is disclosed in which the rear wheel steering angle is controlled so that the vehicle rear end point does not overhang the trajectory.

[0004]

However, in the above-mentioned conventional rear wheel steering angle control system, the clutch disengagement or the neutral state in the manual transmission vehicle or the neutral state in the automatic transmission vehicle is not judged, and therefore, the slope road is not performed. If the vehicle makes a reverse turn with the clutch disengaged from the stopped state, it will be mistakenly judged to be forward even though it is a reverse turn, and a large error will occur in the trajectory of the vehicle used to calculate the rear wheel steering angle. I will end up.

For example, as shown in FIGS. 14 and 15,
When the vehicle shifts from a flat road to a stop on a slope, and the clutch is disengaged while the gear position is in 1st gear from this stop, the vehicle is turned backward by turning the steering wheel to make a temporary stop on a flat road. During the transition from the state to the flat road temporary stop state, the controller erroneously determines the behavior of the vehicle as forward movement. Then, when the state is changed to the forward turning state by operating the right-turn steering wheel, the turning radius becomes large, so that the value desired by the designer cannot be obtained for the rear wheel steering angle after this misjudgment. , Turning performance deteriorates.

The present invention has been made in view of the above problems, and a first object of the present invention is to control a rear wheel steering angle by following a traveling locus to improve a small turning performance in a low vehicle speed range. The purpose of the device is to ensure a small turning performance by following a desired traveling locus even when a state in which the forward and backward movement of the vehicle is unknown is included during traveling.

The second purpose is, in addition to the first purpose, when the forward / backward movement of the vehicle is known from a state in which the forward / backward movement of the vehicle is unknown, the rear wheel steering angle control is reliably performed by following the running trajectory. It is to try to recover.

[0008]

In order to achieve the above first object, the vehicle rear wheel steering angle control device according to the first aspect of the present invention is characterized by the steering wheel as shown in FIG. Front wheel steering angle detection means a for detecting the steering wheel angle or front wheel steering angle of the wheel, vehicle speed detection means b for detecting the vehicle speed, brake state detection means c for detecting whether or not the brake is operating, and transmission gears. Gear position detecting means d for detecting the position, clutch state detecting means e for detecting whether or not the clutch of the transmission is connected, the front wheel steering angle signal, the vehicle speed signal, the brake operation signal, and the gear position signal. And the clutch actuation signal are input, and the rear wheel steering angle target value is set based on the traveling locus of the vehicle front end point so that the vehicle rear end point does not project. A vehicle that follows a traveling locus including a step f and rear wheel steering angle control means h that controls a rear wheel steering angle varying mechanism g so that the actual rear wheel steering angle matches the rear wheel steering angle target value. In the rear wheel steering angle control device for vehicle, a vehicle stop determination unit f1 that inputs the vehicle speed signal and the brake operation signal to the rear wheel steering angle target value setting means f and determines whether or not the vehicle is stopped. Then, the vehicle speed signal, the clutch operation signal, the gear position signal, and the vehicle stop determination signal detected by the vehicle stop determination unit f1 are input to determine whether the vehicle is moving forward or backward. Forward / backward movement determination unit f
2, and when the vehicle forward / rearward traveling signal detected by the forward / rearward traveling determination unit f2 is forward or backward, the rear wheel steering angle target value based on the traveling locus of the vehicle is calculated from the front wheel steering angle signal and the vehicle speed signal. A rear wheel steering angle target value calculation unit f3 during traveling,
And a trajectory following rear wheel steering angle target value calculation canceling section f4 for canceling calculation of the rear wheel steering angle target value based on the traveling trajectory of the vehicle when the vehicle forward and backward signal is unknown. .

In order to achieve the second object, the rear wheel steering angle control device for a vehicle according to the second aspect of the present invention is the vehicle for the vehicle according to the first aspect as shown in the claim correspondence diagram of FIG. In the rear wheel rudder angle control device, the rear wheel rudder angle target value setting means f calculates the rear wheel rudder angle target value during normal traveling when the vehicle forward / rearward travel signal changes from unknown forward / reverse travel to forward or reverse travel signal. It is characterized in that an initial setting section f5 for initializing the section f3 is added.

[0010]

The operation of the first invention will be described.

At the time of turning, in the vehicle stop judging section f1, the vehicle speed signal from the vehicle speed detecting means b and the brake state detecting means c.
The brake operation signal from the vehicle is input to determine whether or not the vehicle is stopped, and the forward / reverse determination unit f2 determines the vehicle speed signal, the clutch operation signal from the clutch state detecting means e, and the gear from the gear position detecting means d. By inputting the position signal and the vehicle stop determination signal detected by the vehicle stop determination unit f1, it is determined whether the vehicle is moving forward or backward.

When the forward / backward traveling signal of the vehicle detected by the forward / rearward traveling determination section f2 indicates forward or reverse, in the normal traveling rear wheel steering angle target value calculation section f3, the front wheel steering angle from the front wheel steering angle detection means a. The rear wheel steering angle target value based on the traveling path of the vehicle is calculated from the signal and the vehicle speed signal, and the rear wheel steering angle control means h adjusts the rear wheel steering angle target value so that the actual rear wheel steering angle matches the rear wheel steering angle target value. The wheel steering angle varying mechanism g is controlled.

On the other hand, when the forward / rearward traveling signal of the vehicle detected by the forward / rearward traveling determination section f2 is unknown, the locus following rear wheel steering angle target value calculation canceling section f4 determines the rear wheel steering angle target based on the traveling locus of the vehicle. The calculation of the value is stopped.

Therefore, the forward / reverse traveling determination portion f2 may be used to change the vehicle speed after the vehicle is stopped, for example, in the case where the vehicle is stopped and the vehicle is stopped and the clutch position is neutral or the clutch is disengaged in the case where the vehicle is making a reverse turn while the clutch is disengaged. If it is determined that the vehicle's forward / backward movement is unknown, the calculation of the rear wheel steering angle target value based on the vehicle's running trajectory is stopped, and the vehicle's forward / backward traveling state is unknown. Even if it is included in the inside, the small turning performance by following the desired traveling locus is secured.

The operation of the second invention will be described.

After the forward / backward traveling signal of the vehicle is unknown, the locus-following rear wheel steering angle target value calculation canceling unit f4 stops the calculation of the rear wheel steering angle target value based on the traveling locus of the vehicle.
When the detection signal from the forward / rearward traveling determination section f2 is changed to a forward or backward signal, the initial setting section f5 initializes the rear wheel steering angle target value calculation section f3 during normal traveling.

Therefore, the front end point locus data and the like which are stored and set at the time of turning before it is detected that the forward / backward movement is unknown are cleared, and a new data is created from the beginning. The influence on the wheel steering angle control is eliminated.

[0018]

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

First, the structure will be described.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which the vehicle rear wheel steering angle control device of the embodiment is applied.

In FIG. 2, the embodiment apparatus comprises a steering angle sensor 1 (corresponding to the front wheel steering angle detecting means a) for detecting a steering wheel steering wheel angle or a front wheel steering angle, and a vehicle speed sensor 2 for detecting a vehicle speed (vehicle speed detection). (Corresponding to the means b), a brake switch 3 (corresponding to the brake state detecting means c) for detecting whether the brake is operating, and a gear switch 4 (corresponding to the gear position detecting means d) for detecting the gear position.
And a clutch switch 5 (corresponding to the clutch state detecting means e) for detecting whether or not the clutch of the transmission is disengaged, a steering angle sensor 1, a vehicle speed sensor 2, a brake switch 3, a gear switch 4, a clutch switch 5
Detected front wheel steering angle signal θ, vehicle speed signal V, brake actuation signal SB, gear position signal SG, clutch actuation signal S
The rear wheel steering angle controller 6 (corresponding to the rear wheel steering angle target value setting means f) that sets the rear wheel steering angle target value δ _R ^* from C, and the actual rear wheel steering angle δ _R is the rear wheel steering angle target value. A rear wheel steering angle actuator 7 (corresponding to the rear wheel steering angle control means h) for controlling the rear wheel steering mechanism 8 (corresponding to the rear wheel steering angle varying mechanism g) so as to match δ _R ^* . ..

FIG. 3 is a block diagram showing in detail the contents of the rear wheel steering angle controller 6, which is a feature of the present invention.

In FIG. 3, the rear wheel steering angle controller 6
Is the vehicle stop determination unit 10 (corresponding to the vehicle stop determination unit f1)
And the forward / backward traveling determination unit 20 (corresponding to the forward / backward traveling determination unit f2),
Normal running rear wheel rudder angle target value calculation unit 30 (corresponding to normal running rear wheel rudder angle target value calculation unit f3) and rear wheel steering unknown command rear wheel steering angle command value calculation unit 40 (trajectory following rear wheel rudder angle) (Corresponding to the target value calculation suspension unit f4) and the traveling locus data initialization unit 5
0 (corresponding to the initial setting section f5).

The vehicle stop determination unit 10 is a determination unit that receives the vehicle speed signal V and the brake actuation signal SB to determine whether the vehicle is stopped.

The forward / backward judging section 20 receives the vehicle speed signal V, the gear position signal SG, the clutch actuating signal SC, and the vehicle stop judging signal SW detected by the vehicle stop judging section 10 to input whether the vehicle is moving forward or backward. It is a determination unit that determines whether the vehicle is moving forward or backward.

The rear wheel steering angle target value calculation unit 30 during the normal running
Is a rear-wheel steering angle target value δ _R1 based on the traveling locus of the vehicle based on the front-wheel steering angle signal θ and the vehicle speed signal V when the vehicle front-rear traveling signal SFB detected by the front-rear traveling determination unit 20 is forward or backward. ^This is a calculation unit that calculates ^* .

Rear wheel steering angle command value calculation unit 4 when the forward / backward movement is unknown
0 is when the vehicle forward / reverse signal SFB is unknown.
A calculation unit that stops the calculation of the rear wheel steering angle target value δ _R1 ^* based on the traveling path of the vehicle and calculates a rear wheel steering angle command value δ _R2 ^* smaller than the absolute value of the rear wheel steering angle target value δ _R1 ^*. Is.

The traveling locus data initialization section 50
Initially initializes the travel locus data set in the normal running rear wheel steering angle target value calculation unit 30 when the vehicle forward / reverse travel signal SFB changes from unknown forward / reverse travel to forward or reverse travel signal. It is a setting unit.

Next, the operation will be described.

[Rear Wheel Steering Angle Control Operation] FIG. 4 is a flowchart showing the flow of the rear wheel steering angle control operation processing performed by the rear wheel steering angle controller 6, and each step will be described below.

In step 101, the vehicle speed signal V detected by the vehicle speed sensor 2 and the brake actuation signal SB detected by the brake switch 3 are input.

At step 102, it is judged from the vehicle speed signal V and the brake actuation signal SB at step 101 whether or not the vehicle is traveling.

In step 103, it is judged whether or not the vehicle has traveled a certain distance.

In step 104, the front wheel steering angle signal θ and the vehicle speed signal V are input.

In step 105, this front wheel steering angle signal θ
From the vehicle speed signal V and the vehicle speed signal V, according to the method described in JP-A-2-74473, the rear wheel steering angle target value δ _R1 ^* during normal traveling
Is calculated.

In step 106, the forward / rearward traveling unknown flag F
It is determined whether LG is FLG ≠ 1.

In step 107, the rear wheel steering angle target value δ _R ^* (= δ _R1 ^* + δ _R2 ^* for the rear wheel steering angle actuator 7 ⁾
Δ _R2 ^* = 0 during normal driving, and δ _R1 ^* = when forward / backward travel is unknown
A control command for obtaining 0) is output.

In step 108, the vehicle speed signal V, the clutch operation signal SC and the gear position signal SG are input.

At step 109, it is judged if the vehicle speed signal V ≠ 0.

At step 110, it is judged if the clutch is engaged.

At step 111, it is judged if the gear position is not in neutral. In step 112, the front wheel steering angle signal θ and the vehicle speed signal V are input.

In step 113, the rear wheel steering angle command value δ _R2 ^* is calculated based on the front wheel steering angle signal θ and the vehicle speed signal V when the vehicle is in the uncertain forward or backward direction.

In step 114, the forward / reverse unknown flag F
LG is set to FLG = 1. In step 115, the forward / backward traveling unknown flag FLG is set to FLG = 0. In step 116, the traveling locus data set in the rear wheel steering angle target value calculation unit 30 during normal traveling is initialized.

[Rear Wheel Steering Angle Control During Normal Traveling] During normal traveling, the flow proceeds from step 101 → step 102 → step 103 → step 104 → step 105 → step 106 → step 107 in the flow chart of FIG. The wheel steering angle is controlled.

That is, during normal traveling, step 10
5, the rear wheel steering angle signal θ and the vehicle speed signal V are used to limit the amount of protrusion of the vehicle rear end point to the outside of the turn based on the method described in JP-A-2-74473, that is, based on the vehicle front end point trajectory data. the calculated wheel steering angle target value [delta] _R1 ^*, in step 107, the rear wheel steering angle target value [delta] _R1
^The rear wheel steering angle is controlled so that ^* can be obtained.

Therefore, as described in Japanese Patent Laid-Open No. 2-74473, the small turning performance at the time of turning is greatly improved as compared with a vehicle which simply performs rear wheel reverse phase control, and as a result, a large living space. It is possible to realize an ultra-long wheelbase vehicle that can improve steering stability and riding comfort.

[Rear wheel steering angle control when forward / backward travel is unknown] When forward / backward travel is unknown, step 101 →
Step 102 → Step 108 → Step 109 → Step 110 (→ Step 111) → Step 112 →
The rear wheel steering angle is controlled in the flow of step 113 → step 114 → step 107.

In this control, it is judged whether or not the forward / reverse movement is unknown after it is judged in step 102 that the vehicle is stopped, and then the vehicle speed comes out even though the clutch is disengaged or the gear position is in neutral. When the determination condition (step 108 to step 111) is satisfied, it is determined that the forward / reverse traveling is unknown, and the forward / reverse traveling determination unit 20 outputs the vehicle forward / rearward traveling unknown signal SFB = 1 to the rear wheel steering angle target during normal traveling. The value is transmitted to the value calculation unit 30 and the front / rear and rear wheel steering angle command value calculation unit 40. After it is determined that the vehicle is stopped, if the vehicle speed is output but the clutch is engaged, and the forward / rearward movement of the vehicle is confirmed at a gear position other than neutral, the process proceeds from step 11 to step 103. The rear wheel steering angle control during normal traveling is performed.

When it is determined that the vehicle is not moving forward or backward, the process proceeds from step 112 to step 113. In step 113, the vehicle is moved forward or backward based on the front wheel steering angle signal θ and the vehicle speed signal V. The rear wheel steering angle command value δ _R2 ^* in the unknown state is calculated.

Here, the rear wheel steering angle command value δ _R2 ^* can be set, for example, by selecting one of the following three modes.

It is given by δ _R2 ^* = 0. That is, the rear wheel steering angle is maintained at the neutral position in order to prevent the vehicle from wobbling when moving backward.

Δ _R2 ^* = − C · θ (1) Here, C is a front / rear wheel steering angle ratio constant, which is set by the vehicle speed corresponding constant map shown in FIG.

This constant map corresponding to vehicle speed is a reverse phase control in which the front and rear wheel steering angle ratio is constant in order to ensure a small turning property in the extremely low vehicle speed range, and the vehicle behavior changes suddenly when the vehicle speed enters the low vehicle speed range. To prevent this, the front-rear wheel steering angle ratio that obtains the opposite phase is gradually decreased, and when the vehicle speed increases, δ _R2 ^* = 0 is set in order to prevent the vehicle from wobbling during reverse.

[0054] [delta] _R2 ^* = - given in ^{[1 {(1 + AV 2} ) L} / {(1 + A M V 2) L M}] · θ / N ... (2).

[0055] However, N; is a model car wheel base; actual vehicle of the steering ratio A; of the actual vehicle wheelbase A _M;; vehicle stability factor L model cars of the stability factor L _M. The above equation (2) is derived as follows.

[0056] steady yaw rate dψ _VS of control vehicle (4-wheel steering wheel) becomes the following equation.

D ψ _VS = V / {(1 + AV ² ) L} · {(θ / N) −δ _R } (3) where δ _R is the rear wheel steering angle.

Further, the target steady-state yaw rate dψ _MS of the model vehicle is given by the following equation.

[0059] _{dψ MS = V / {(1} + A M V 2) L M} · (θ / N) ... (4) where, matching the steady yaw rate d [phi] _VS of a four-wheel steering vehicle in a steady yaw rate d [phi] _MS of the model vehicle The rear wheel rudder angle δ _R required for this is expressed by equation (3) = (4), that is, d ψ _VS = d ψ _MS, and δ _R is δ _R2 ^* , δ _R2 ^* = [1-{(1 + AV ² ) L} / {(1 + A _M V
² ) L _M }] · θ / N is obtained.

Therefore, for example, in the case where the vehicle turns backward while the clutch is disengaged from the state where the vehicle is stopped on a slope, after the vehicle is stopped, the gear position is neutral or the clutch is disengaged and the vehicle speed is detected. If it is determined that the vehicle is not moving forward or backward, the calculation of the rear wheel steering angle target value based on the vehicle's running trajectory is stopped, so it is desirable to include a state in which the vehicle is not moving forward or backward while driving. The small turning performance is ensured by following the running locus.

That is, when the rear wheel steering angle control is executed without detecting the clutch state or the gear position, although the vehicle is reversing when the vehicle is turning backward with the clutch disengaged from the state where the vehicle is stopped on the slope, it is in reverse. By erroneously determining that the vehicle is in the forward traveling state, and using the traveling trajectory data that has been erroneously determined, the subsequent rear wheel steering angle control is performed, which adversely deteriorates the small turning performance.

[Return from control when unknown forward / reverse travel to normal control] After the control when unknown forward / reverse travel is performed, it is determined that the running state of the vehicle is forward or reverse, and the rear wheel steering angle during normal travel is determined. When returning to the control, the forward / reverse traveling unknown flag is set to FLG = 1 in step 1145 of the control when the vehicle is not traveling forward / backward, so that in the flowchart of FIG. In the control of 1, the flow proceeds from step 101 to step 106 to step 115 → step 116 → step 107.

That is, in step 115, the forward / reverse traveling unknown flag FLG is set to FLG = 0, and in step 116
The traveling locus data set in the rear wheel steering angle target value calculation unit 30 during normal traveling is initialized.

Therefore, the front end point locus data and the like stored and set at the time of turning before it is detected that the forward / backward movement is unknown are cleared, and a system for newly preparing data from the beginning is used. The influence on the wheel steering angle control is eliminated.

[Simulation Results] Here, a simulation was performed to compare the control method of the present invention with the conventional control method. 6 and 7 are input diagrams of the simulation, FIGS. 8 and 9 are simulation result diagrams of the conventional control method, and FIGS. 10 to 13 are simulation result diagrams of the control method of the present invention.

* Vehicle specifications used for simulation Vehicle mass: 1700 kg Front wheel equivalent cornering power: 37417.7 N / ra
d Rear-wheel cornering power; 60000.0N / rad Distance from front axle to center of gravity; 1.425m Distance from rear axle to center of gravity; 1.425m Wheelbase; 2.85m Yaw moment of inertia; 2450kg m ² Vehicle Stability factor: 1.5 * 10 ^-3 Distance from vehicle front end to center of gravity; 2.295m Distance from vehicle rear end to center of gravity; 2.63m Steering gear ratio; 17.14 Distance between vehicle speed pulses; 0.07m Specifications of control target vehicle (model vehicle) Wheelbase; 2.4m Stability factor; 1.5 * 10 ^-3 * Simulation situation First, simulation situation setting is shown in FIGS. 8, 10 and 12. Thus, in a T-shaped road having a straight road having a wide road width and a slope and an intersection having a narrow road width orthogonal to the straight road, With the vehicle parked in the up direction on the slope, with the gear position in the 1st speed etc., disengage the clutch and once move to the crossroad side by backward turning, then change the direction of running direction by forward turning It is set to the situation that the vehicle runs. Then, as the simulation input, as shown in FIG. 6, a steering angle input in which a right turn steering is performed from a stopped state on a slope, and then a left turn steering is switched until the same steering angle is obtained, and as shown in FIG. The vehicle speed input is such that the vehicle turns backward on the turning steering side, stops once, and then moves forward on the left turning operating side.

* Simulation Result by Conventional Control FIGS. 8 and 9 are simulation result diagrams by the conventional control method described in Japanese Patent Application Laid-Open No. 2-74473, even though the vehicle is turning backward on the slope with the clutch disengaged. However, as shown in FIG. 9, since the rear wheel steering angle is controlled even in the reverse turning range, the rear wheels are delayed from being steered when shifting from the reverse turning to the forward turning. As shown in 8, the turning radius on the forward side is large.

* Simulation result when δ _R2 ^* = 0 when forward / backward travel is unknown FIG. 10 and FIG. 11 show rear wheel steering angle command value δ when forward / backward travel is unknown.
FIG. 11 is a simulation result diagram when _R2 ^{* is set} to δ _R2 ^* = 0, and it is determined that forward / backward traveling is unknown when the vehicle is making a reverse turn with the clutch disengaged on a slope, and as shown in FIG. 11, δ _R2 ^*
= 0, the rear wheels are steered with good response when shifting from the reverse turn to the forward turn, and as shown in FIG. 10, the turning radius on the forward side is suppressed smaller than in the case of FIG. 9. .

* Simulation result when forward / reverse is unknown δ _R2 ^* = − C · θ FIG. 12 and FIG. 13 show rear wheel steering angle command value δ when forward / reverse is unknown.
FIG. 14 is a simulation result diagram when _R2 ^{* is set} to δ _R2 ^* = − C · θ, and it is determined that forward / backward traveling is unknown when the vehicle is making a reverse turn with the clutch disengaged on a slope, and as shown in FIG.
Since δ _R2 ^* = − C · θ, the turning radius on the reverse side is suppressed to a smaller value than that in the case of FIG. 10 by the reverse-phase steering of the rear wheels in the reverse turn shape, and the vehicle position at the intersection is At a more swiveled position where a small turn is effective, and at the subsequent transition to forward turning, the rear wheels are steered with good response as in the case of FIG. 11, and as a result, as shown in FIG. The turning radius on the forward side is further reduced by the amount as compared with the case of FIG.

Next, the effect will be described.

(1) In the rear wheel steering angle control device that follows the traveling locus in which the small turning property is improved in the low vehicle speed range, the vehicle speed signal V and the brake operation signal are set when the rear wheel steering angle target value δ _R ^* is set. Vehicle stop determination unit 10 for inputting SB to determine whether or not the vehicle is stopped, vehicle speed signal V, gear position signal SG, clutch actuation signal SC, and vehicle stop determination detected by the vehicle stop determination unit 10. The front / rear traveling determination unit 20 which inputs the signal SW to determine whether the vehicle is traveling forward or backward and the vehicle forward / reverse traveling signal SFB detected by the forward / reverse traveling determination unit 20 is a front wheel. A normal running rear wheel steering angle target value calculation unit 30 that calculates a rear wheel steering angle target value δ _R1 ^* based on the traveling locus of the vehicle based on the steering angle signal θ and the vehicle speed signal V, and the vehicle forward / rearward traveling signal SFB moves forward and backward. When you are unsure, The rear wheel steering angle target value based on the line trajectory δ
Stops calculation of _R1 ^*, a rear wheel steering angle target value [delta] _R1 ^* of the absolute value is smaller than the rear wheel steering angle command value [delta] _R2 ^* reverse unclear when rear-wheel steering angle command value calculating section 40 before calculating the, the Since the configuration is provided, it is possible to secure the small turning performance by following the desired traveling locus even when the vehicle is traveling and the state in which the forward / backward movement is unknown is included.

(2) When setting the rear wheel steering angle target value δ _R ^* , when the vehicle forward / rearward traveling signal SFB changes from unknown forward / reverse traveling to forward or reverse traveling signal, the rear wheel steering angle target value calculating section 30 during normal traveling Since the traveling locus data initializing unit 50 for initializing the traveling locus data set in step S1 is added by the initialization process, when the forward / reverse traveling of the vehicle is known from the state in which the forward / rearward traveling of the vehicle is unknown, it is possible to reliably It is possible to return to the rear wheel steering angle control by following the traveling locus.

(3) When it is determined that the vehicle is in the forward / rearward traveling state, if the rear wheel steering angle command value δ _R2 ^* is given by δ _R2 ^* = 0, the vehicle is moved backward by simple control. It is possible to prevent the vehicle from swaying at times.

(4) When it is determined that the vehicle is not in forward / rearward traveling, the rear wheel steering angle command value δ _R2 ^{* is set} to δ _R2 ^* =-C
When θ is given, the anti-phase control in which the front-rear wheel steering angle ratio is constant makes it possible to secure a small turning property in the reverse turn as shown in FIG.

(5) When it is determined that the vehicle is not in forward / rearward traveling, the rear wheel steering angle command value δ _R2 ^{* is set} to δ _R2 ^* = [1-
^{{(1 + AV 2) L} } / {(1 + A M V 2) L M}] ·
In the case of giving θ / N, by the rear wheel steering angle control that secures the turning yaw rate, it is possible to secure the small turning ability in the backward turning without feeling awkward.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

[0077]

According to the first invention of claim 1,
In the rear-wheel steering angle control device that follows the traveling locus to improve the small turning ability in the low vehicle speed range, whether the vehicle is stopped by inputting the vehicle speed signal and the brake operation signal to the rear wheel steering angle target value setting means. Before and after whether the vehicle is moving forward or backward, input the vehicle stop determination unit that determines whether or not the vehicle speed signal, the clutch operation signal, the gear position signal, and the vehicle stop determination signal detected by the vehicle stop determination unit are input. A forward / rearward traveling determination unit that determines whether the vehicle is moving forward, and when the vehicle forward / rearward traveling signal detected by the forward / rearward traveling determination unit is forward or reverse, calculates a rear-wheel steering angle target value based on the vehicle's running trajectory from the front-wheel steering angle signal and vehicle speed signal Normal-wheel rear-wheel steering angle target value calculation unit and track-following rear-wheel steering angle target value calculation that stops calculation of the rear-wheel steering angle target value based on the vehicle's traveling path when the vehicle forward / backward signal is unknown. And a discontinuation section. , The effect is obtained that also the forward-reverse is unknown states of the vehicle is included in the travel it is possible to ensure the maneuverability turning performance with the desired travel locus tracing.

According to a second aspect of the present invention, in the rear wheel steering angle control device according to the first aspect, when the forward / rearward traveling signal of the vehicle changes from an unknown forward / rearward traveling signal to a forward or reverse traveling signal, during normal traveling. In addition to the above effects, when the vehicle's forward / rearward movement is known from a state in which the vehicle's forward / rearward movement is unknown, reliable driving is ensured because an initial setting unit for initializing the rear wheel steering angle target value calculation unit is added. The effect that the rear wheel steering angle control can be restored by following the trajectory is obtained.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a rear wheel steering angle control device of the present invention.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which a rear wheel steering angle control device according to an embodiment of the present invention is applied.

FIG. 3 is a block diagram of a main part configuration of an apparatus according to an embodiment.

FIG. 4 is a flowchart showing a flow of rear wheel steering angle control operation processing performed by a rear wheel steering angle controller of the embodiment apparatus.

FIG. 5 is a constant map diagram for setting a rear wheel steering angle command value in the embodiment apparatus.

FIG. 6 is a steering angle input diagram for simulation.

FIG. 7 is a vehicle speed input diagram for simulation.

FIG. 8 is a vehicle trajectory diagram showing a simulation result in a conventional control method.

FIG. 9 is a rear wheel steering angle diagram showing a simulation result in a conventional control method.

FIG. 10 is a vehicle trajectory diagram showing a simulation result when δ _R2 ^* = 0 when the forward / reverse movement is unknown.

FIG. 11 is a rear wheel steering angle diagram showing a simulation result when δ _R2 ^* = 0 when forward and backward movement is unknown.

FIG. 12 is a vehicle trajectory diagram showing a simulation result when δ _R2 ^* = − C · θ when forward / rearward travel is unknown.

FIG. 13 is a rear wheel steering angle diagram showing a simulation result when δ _R2 ^* = − C · θ when forward / rearward travel is unknown.

FIG. 14 is a perspective view showing a traveling locus of a vehicle under conventional control.

FIG. 15 is a plan view showing a traveling locus of a vehicle under conventional control.

[Explanation of symbols]

 a front wheel steering angle detection means b vehicle speed detection means c brake state detection means d gear position detection means e clutch state detection means f rear wheel steering angle target value setting means g rear wheel steering angle variable mechanism h rear wheel steering angle control means f1 vehicle Stop determination unit f2 Forward / backward movement determination unit f3 Normal running rear wheel steering angle target value calculation unit f4 Trajectory following rear wheel steering angle target value calculation suspension unit f5 Initial setting unit

Claims (2)

[Claims] 1. A front wheel steering angle detecting means for detecting a steering wheel steering wheel angle or a front wheel steering angle, a vehicle speed detecting means for detecting a vehicle speed, and a brake state detecting means for detecting whether a brake is operating or not. Gear position detecting means for detecting the gear position of the transmission, clutch state detecting means for detecting whether or not the clutch of the transmission is connected, the front wheel steering angle signal, the vehicle speed signal, the brake operation signal, and the gear position Signal and the clutch actuation signal to input the rear wheel steering angle target value setting means for setting the rear wheel steering angle target value based on the traveling locus of the vehicle front end point so that the vehicle rear end point does not overhang, and the actual rear wheel A vehicle according to a traveling locus following, which comprises a rear wheel steering angle control means for controlling a rear wheel steering angle variable mechanism so that the steering angle matches the rear wheel steering angle target value. In the wheel steering angle control device, the rear wheel steering angle target value setting means receives the vehicle speed signal and the brake actuation signal, and determines a vehicle stop and a vehicle stop determination unit, the vehicle speed A forward / backward movement determination unit that inputs a signal, the clutch actuation signal, the gear position signal, and a vehicle stoppage determination signal detected by the vehicle stoppage determination unit to determine whether the vehicle is moving forward or backward. When the vehicle forward / rearward traveling signal detected by the forward / rearward traveling determination unit is forward or backward, the rear wheel steering angle target value based on the traveling locus of the vehicle is calculated from the front wheel steering angle signal and the vehicle speed signal. A wheel steering angle target value calculation unit, and a trajectory following rear wheel steering angle target value calculation suspension unit that suspends calculation of the rear wheel steering angle target value based on the traveling trajectory of the vehicle when the vehicle forward / reverse signal is unknown. Specially having A rear wheel steering angle control device for a vehicle. 2. The vehicle rear wheel steering angle control device according to claim 1, wherein the rear wheel steering angle target value setting means changes the vehicle forward / reverse signal from an unknown forward / reverse signal to a forward or reverse signal. A rear wheel steering angle control device for a vehicle, further comprising an initial setting section for initializing the rear wheel steering angle target value calculation section during normal traveling.