Composition of the electronic control part of the 4WS system

Sensors

In the 4WS system, the sensor mainly detects the vehicle's motion state and generates corresponding electrical signals to transmit to the ECU. The ECU performs corresponding data analysis and calculations based on the received electrical signals and generates corresponding control signals.

4.1.1 Front and rear wheel angle sensors

The front and rear wheel steering angle sensors are installed near the wheels of the front and rear wheel steering mechanisms of the vehicle. The front and rear wheel steering angle sensors do not contact the wheels and are non-contact Hall element sensors. The function of the front and rear wheel steering angle sensors is to detect the instantaneous deflection angle of the front and rear wheels of the vehicle in real time.

4.1.2 Vehicle speed sensor

The vehicle speed sensor uses a photoelectric sensor, which is installed near the speedometer. It is used to detect the vehicle's speed, transmit the detected speed information to the four-wheel steering ECU in the form of a pulse signal, and input the same information into the automatic transmission ECU in the form of an electrical signal.

4.1.3 Vehicle yaw rate sensor

A body yaw angular velocity sensor is installed on the body at the center of mass of the vehicle. The main working content of the sensor is to detect the angular velocity of the body yaw when the vehicle is turning, and output the detected body yaw angular velocity to the ECU in the form of an electrical signal. After analysis and calculation by the ECU, the corresponding control model is output to achieve real-time control of the body's yaw stability when the vehicle is turning.

4.2. Electronic Control Unit

The electronic control unit is ECU, which is a unit in the vehicle electronic control system that performs analysis and calculations and outputs control signals to corresponding components. In the 4WS system, ECU also analyzes and calculates the UI vehicle motion signal and outputs corresponding control signals to control the stepper motor action.

4.3. Stepper Motor

The advantages of using a stepper motor as a digital control motor are: the angular displacement of the stepper motor is proportional to the number of input pulses, and the follow-up is good; the dynamic response ability is strong and it is easy to achieve forward and reverse rotation, speed change, start and stop; the structure is simple and durable; the anti-interference ability is strong, etc. The rear wheel steering mechanism is controlled by the stepper motor and outputs the corresponding angle and torque after receiving the control command of the ECU to control the steering of the rear wheel. The stepper motor is the rear wheel drive actuator in the four-wheel steering system.

4.4. Rear wheel steering transmission mechanism

The rear-wheel steering transmission mechanism varies according to the structural form of the vehicle model. It can use a traditional steering mechanism form or be personalized according to the suspension and steering requirements of a specific vehicle model.