JPH03231066A - Safety device for front/rear wheel steered vehicle - Google Patents

Abstract

PURPOSE:To carry out stable traveling without giving an uneasy feeling to a driver even if anomaly is generated, by detecting the anomaly of a system, suspending the steering control for rear wheels, detecting the stable state of a vehicle, and returning the rear wheels to a neutral state. CONSTITUTION:In a front/rear wheel steered vehicle, rear wheels C are steering- controlled according to the steered state of the front wheels. In this case, a means A detects the anomaly of a system. Further, the steering control for the rear wheels C is suspended by a means B on the basis of the detected anom aly of the system. Further, a means D detects the stable state of the vehicle. The rear wheels C are returned to a neutral state by a means E on the basis of the detected stable state of the vehicle. Accordingly, even if anomaly is generated, safe traveling can be executed without giving an uneasy feeling to a driver.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a safety device for a front and rear wheel steered vehicle that controls steering of the rear wheels according to the steering state of the front wheels.

[Prior Art] Conventionally, as a safety device for such a vehicle with front and rear wheel steering, the one described in Japanese Patent Application Laid-open No. 141877/1987 is known.

This device has an electromagnetic clutch installed between the motor that steers the rear wheels and a worm reducer with a reversal efficiency of O or less, and in the event of an abnormality such as a failure of each sensor or a disconnection of the power line, the motor At the same time, the electromagnetic clutch is disengaged.

Also known is a vehicle in which the rear wheels are immediately returned to the neutral position when an abnormality as described above occurs.

[Problem to be Solved by the Invention] However, in such a conventional example, when the power to the motor is cut off and the electromagnetic clutch is disengaged, when an abnormality occurs, the rear wheel steering angle remains at that position. Since it is fixed, there is a problem in that the behavior of the vehicle becomes unstable depending on the steering state of the rear wheels, giving the driver a sense of anxiety.

Furthermore, in a vehicle that immediately returns the rear wheels to the neutral position in the event of an abnormality, there is a problem in that the rear wheel steering angle changes unexpectedly during driving, especially when turning at high speed, which is dangerous.

The purpose of the present invention is to solve such conventional problems and to avoid causing anxiety to the driver even when an abnormality occurs.
An object of the present invention is to provide a safety device for a vehicle with front and rear wheel steering, which allows safe driving.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system abnormality detection means for detecting an abnormality in the system in a front and rear wheel steered vehicle that controls steering of the rear wheels according to the steering state of the front wheels. a rear wheel steering control stop means for stopping the amount of steering of the rear wheels in response to abnormality detection by the system abnormality detection means; a vehicle stable state detection means for detecting a stable state of the vehicle; The vehicle is characterized by comprising a rear wheel neutral state return means for returning the rear wheels to a neutral state when a stable state of the vehicle is detected by the detection means.

[For production]

According to the present invention, when an abnormality in the system is detected, the rear wheel steering control is stopped and the rear wheel steering angle is fixed at that position. Then, when a stable state of the vehicle is detected, the rear wheels are returned to the neutral state.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block configuration diagram showing one embodiment of the present invention, in which A is a system abnormality detection means for detecting an abnormality in the system, and B is a steering of a rear wheel C in response to an abnormality detected by the system abnormality detection means A. amount (rear wheel steering control stopping means for stopping wholesale, D
E is a vehicle stable state detection means for detecting a stable state of the vehicle;
is a rear wheel neutral state return means for returning the rear wheels C to a neutral state when a stable state of the vehicle is detected by the vehicle stable state detection means.

Next, FIG. 2 is a system configuration diagram showing an embodiment of the present invention. In the figure, 1 is an on-vehicle battery, 2 is an ignition switch, 3 is a steering angle sensor, and a steering wheel (not shown) is connected to the steering wheel. Generates a signal proportional to the steering angle and a neutral position signal. 4 is a vehicle speed sensor that detects the vehicle speed; 5 is a brake switch that is turned on in response to depression of the brake pedal; 6 is a stop lamp that lights up when the brake switch 5 is turned on; and 7 is when a clutch is connected or disconnected from the drive system. A clutch switch is turned on, and 8 is a warning lamp.

Next, reference numeral 9 denotes a rear wheel steering actuator, and in this embodiment, a steering motor 9A for imparting a predetermined amount of steering to the rear wheels (not shown) and a steering motor 9A are used. A limiting motor 9 for driving a mechanism that reduces the applied steering amount by a predetermined ratio and limits the maximum steering angle of the rear wheels.
It is equipped with B. This restriction mechanism is explained in detail in Japanese Patent Application No. 1-275019, which was previously filed by the present applicant. Rotation amount detection sensors 9 correspond to the motors 9A and 9B and detect their respective rotation amounts.
C and 9D are provided.

10 is a control unit that sends drive signals for the steering motor 9A and the limiting motor 9B based on the input signals of the various sensors described above, and the CPU 10AI, RO
M10A, a microcomputer IOA equipped with a RAM 10A3, a power supply circuit 10B for the microcomputer 10A, a steering angle sensor 3, a vehicle speed sensor 4. An input I/F circuit 10G that converts signals from the brake switch 5 and clutch switch 7 into input signals for the microcomputer 10A, an output I/F circuit 100 to the warning lamp 8, and drives both motors 9A and 9B. A motor drive circuit 10E, a power supply circuit 10F for the motor rotation amount detection sensors 9C and 9D, an analog human power I/F circuit 10G to which analog signals of the rotation amount detection sensors 9C and 9D are manually input, and the analog human power I/F circuit 10G. A/D conversion circuit 1 that converts the signal of /F circuit 10G into digital
It consists of 0H.

Next, an example of the control procedure of this embodiment having the above configuration will be explained in the third section.
This will be explained with reference to the flowchart shown in the figure.

First, the system (when wholesale starts, in step Sl,
The steering angle of the front wheels detected by the steering angle sensor 3 is read, and then, in steps S2 and S3, its steering angular velocity and steering angular acceleration are calculated. Then, in step S4, the vehicle speed detected by the vehicle speed sensor 4 is read.

In step S5, the actual steering angle of the rear wheels determined from the detected values of the rotation amount detection sensors 9C and 9D is read, and in step S6, the actual steering angle of the rear wheels determined from the detection values of the rotation amount detection sensors 9C and 9D is read, and in step S6, the actual steering angle of the rear wheels is read.
The power SII is disconnected to determine whether the B main body, motor drive circuit 10E, wiring, etc. are normal, that is, whether the system is functioning normally. Therefore, if it is determined that the system is normal, the process proceeds to step s7, where a target turning angle for the rear wheels is calculated according to the values of the above-mentioned front wheel steering angle, steering angular velocity, steering angular acceleration, and vehicle speed.

Then, in step S8, output amounts to the steering motor 9A and the limiting motor 9B are calculated based on the error between the target steering angle and the above-mentioned actual steering angle. Note that, from the viewpoint of safety, the output amount of the limiting motor 9B is set so that the maximum steering angle of the rear wheels decreases as the vehicle speed increases. Then, in step S9, the eight forces calculated in step s8 are outputted to the drive circuit 10E of the steering motor 9A and the limiting motor 9B, respectively, and the limiting mechanism is driven to a predetermined ratio state, and the rear wheels are moved to a desired position. A fixed amount of steering is applied.

Under normal conditions, the above-described control routine is executed.

By the way, if it is determined in step S6 that the system is abnormal, the process proceeds to step SIO, where the output for the above-mentioned rear wheel steering control is turned off, and in step Sll, the rear wheel steering angle is changed by turning off this output. A warning lamp 8 is lit to notify the driver that the lock has been fixed.

Then, in step S12, it is determined whether the vehicle speed sensor 4 is normal or not, and if it is normal, step S12 is performed.
Proceed to L3. In this step 13, it is determined whether the vehicle is in a stopped state using the detection result of the normal vehicle speed sensor 4. This determination is not necessarily limited to determining whether the vehicle has come to a complete stop; for example, determining whether the vehicle is traveling at a speed of 5 km/h or less. It may be set based on whether or not it is in a stable state. In step S13, if it is determined that the vehicle is not stopped and is traveling at a predetermined speed,
Returning to step SIO, wait until the vehicle reaches a stopped state or a predetermined low speed state as described above. When the state reaches a stopped state or a low speed state, the process advances to step S14, where the warning lamp 8 is flashed and the driver is informed that the rear wheels are in neutral. After informing that the state will be returned to the neutral state, the rear wheels are returned to the neutral state in step S15.This return action is performed by the steering motor 9.
A, or if the drive control system of the steering motor 9A is malfunctioning, the limiting motor 9B
The limiting mechanism may be driven so that the ratio becomes zero.

Then, in step S16, the process waits until this return operation is completed, and then the process proceeds to step S17, where the warning lamp 8 is turned on again to notify the driver that the system is in an abnormal state and to alert the driver to the need for repair. evoke

On the other hand, if the vehicle speed sensor is not normal as determined in step S12, the above-mentioned control is no longer possible, so the process proceeds to step S18, where it is determined whether the vehicle is traveling straight. Judgment as to whether or not the vehicle is traveling straight is determined based on the signal from the steering angle sensor 3, depending on whether the front wheel steering angle is in a stable state in which it remains within a predetermined small angle range from the neutral position for a predetermined period of time or not. Bye. When the vehicle is not in a straight-ahead state, that is, when it is turning, unnecessarily changing the rear wheel steering angle will make the behavior of the vehicle unstable, which is undesirable. Therefore, the process returns to step SIO and waits until the vehicle is in a straight-ahead state.

If it is determined that the vehicle is traveling straight, the process proceeds to step S19, the warning lamp 8 is blinked, and the process proceeds to step S15 described above.
In steps S20 to S22 corresponding to steps S17 to S17, the rear wheels are returned to a neutral state.

In this way, in this embodiment, the stable state of the vehicle is detected using normally operating sensors, so that detection can be performed reliably.

[Effects of the Invention] As is clear from the above description, according to the present invention, when an abnormality in the system is detected, the steering control of the rear wheels is stopped at that point, and a stable state of the vehicle is detected. Since the rear wheels are sometimes returned to a neutral state, stable driving can be performed without causing anxiety to the driver even if an abnormality occurs.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram showing one embodiment of the present invention, Fig. 2 is a system configuration diagram showing an embodiment of the present invention, and Fig. 3 is an example of a control procedure of an embodiment of the present invention. FIG. 3... Steering angle sensor, 4... Vehicle speed sensor, 9A... Steering motor, 9B... Limiting motor, 9C, 90... Rotation amount detection sensor, 10... Control unit.

Claims (1)

[Scope of Claims] 1) In a front and rear wheel steered vehicle that controls the steering of the rear wheels according to the steering state of the front wheels, a system abnormality detection means for detecting an abnormality in the system; Rear wheel steering control stopping means for stopping steering control of the rear wheels; vehicle stable state detecting means for detecting a stable state of the vehicle; and when the stable state of the vehicle is detected by the vehicle stable state detecting means, A safety device for a front and rear wheel steered vehicle, comprising: a rear wheel neutral state return means for returning the wheels to a neutral state.