JPH0584573U - Failure detection device - Google Patents

Abstract

(57) [Summary] [Objective] An object of the present invention is to provide detection of an encoder failure that is difficult to distinguish from normal operation. [Structure] In a four-wheel steering system including a steering wheel steering angle sensor, a rear steering angle sensor, a wheel speed sensor 5 for both rear wheels, a control unit 8 and a motor actuator 6, the rear wheel speed is always the same when going straight. Therefore, even if either of the front and rear wheel snake angles rolls, software that determines that the rear wheel speed is the same is added to prevent abnormal operation.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a four-wheel steering vehicle for an automobile, and more particularly to failure detection.

[0002]

[Prior Art]

 In the conventional four-wheel steering, the control unit calculates the optimal rear snake angle based on the signals from the encoder attached to the vehicle handle post and the speed sensor attached to the rear wheel, and the rear axle is adjusted accordingly. The motor actuator set to is operated and the feedback control is performed by the signal from the encoder set in the motor actuator.

By the way, by detecting with the software of the control unit, a short circuit to the body or the battery line, noise mixing due to disconnection, etc., it is possible to prevent serious failures such as self-steering in advance. There is.

[0004]

[Problems to be solved by the device]

 However, in the conventional system, it is difficult to detect normal operation, and it will be impossible to detect missing teeth in the encoder, improper mounting of the encoder pulser, etc. For example, when the encoder is not firmly fixed to the rotating shaft and rotates while slipping appropriately, it is not possible to obtain the number of pulses according to the amount of rolling of the rear, and the slip amount is not constant. , The number of pulses when going straight → rolling and the number of pulses when rolling → going straight do not match. For this reason, the wheels will not run straight and will be crab-running, or the difference between the target and the actual snake angle will be large when there is a large amount of slip, and the motor will generate excessive output, resulting in self-steering in the event of a bad situation. There were some problems such as the possibility. Therefore, it is an object of the present invention to provide a failure detection device that can detect an encoder failure that is difficult to distinguish from normal operation.

[0005]

[Means for Solving the Problems]

 Therefore, the present invention solves the problem by adding judgment software to the software of the control unit in order to achieve the above-mentioned object.

[0006]

【Example】

 Next, an embodiment of the present invention will be described with reference to FIGS.

Next, the operation will be described. Figure 2 shows the front and rear corners under normal conditions.

In the figure, 1 is a front wheel, and 2 is a rear wheel. A front wheel (front wheel) 1 is steered by a steering wheel 3, and an incremental type encoder 4 is arranged on a steering shaft. A wheel speed sensor 5 is provided on the rear wheel (rear wheel) 2. A motor actuator 6 is arranged on the rear axle, and an echoda 7 is set on it. Reference numeral 8 denotes a control unit, which calculates an optimum rear snake angle based on signals from the encoder 4 and the wheel speed sensor 5 to operate the motor actuator 6, and is feedback-controlled by a signal from an encoder 7 in the actuator. First, A is a straight traveling state under normal conditions. At this time, the front and rear wheels are in a straight traveling state, and the rear wheel speeds are the same. Next, B shows the case where the steering wheel turns around on a curve or the like. Due to the difference in the inner wheels, VRL is lower than VRR.

Next, FIG. 3 shows the front and rear states at the time of abnormality, but when C is straight ahead, VRL and VRR are the same even if the front and rear wheels may have different snake angles. In addition, when D turns, VRL becomes lower than VRR as in the normal state.

As described above, the rear wheel speeds are normal and are the same regardless of whether they are abnormal when traveling straight, or at different speeds when rolling. In the present invention, this point is used to determine that the sensor is abnormal if the rear wheel speed is the same even if the front wheel or the rear wheel is rolling. FIG. 4 shows a flowchart relating to this.

In the figure, first, it is determined whether the rear wheel speeds are the same. If they are not the same, it means that the vehicle is in the meandering state. Next, it is judged whether the front and rear are traveling respectively by the snake angle data from the encoder, and it is normal when traveling straight ahead and behind. On the other hand, if the vehicle is not traveling straight ahead, it will be considered as a failure, but if it fails immediately, it will be easily affected by noise and so on.

[0012]

[Effect of the device]

 As described above, the present invention has made it possible to make a judgment even for a failure that could not be judged until now, and has the result of preventing abnormal operation of the 4WS system and improving the safety.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

[Fig. 2] Normal state diagram

[Fig. 3] State diagram at the time of abnormality

[Fig. 4] Flow chart

[Explanation of symbols]

 1 Wheel (front wheel) 2 Wheel (rear wheel) 3 Steering 4 Encoder 5 Wheel speed sensor 7 Encoder 8 Control unit

Claims (1)

[Scope of utility model registration request] 1. An incremental type encoder mounted on a steering wheel and a rear actuator to generate a signal according to movement of an axle, and a wheel speed sensor mounted on each wheel to generate a signal according to its speed,
A control unit for calculating a snake angle of a rear wheel from a wheel speed sensor, and a motor actuator for controlling the rear wheel by the control unit, wherein the control unit is provided with software for determining failure detection. Failure detection device.