Application And Research Of Electronic Control Four-wheel Steering Technology

Four-wheel steering (4WS) technology is that introducing a certain corner of therear wheel in the car steering, in order to enhance the driving safety and handingstability when the car at high speed, and improve the vehicle maneuverability under thelow-speed. After the research and analysis of the control strategy, control methods andcurrent situation about4WS both home and aboard, the integrated rear wheel steeringmechanism can’t meet the four wheel steering center to a point in both high-speed andlow-speed rotation, which not only adds abrasion to the tire, but also worse the stabilityin the high speed turning. So considering the four-wheel steering vehicle with two rearwheels independent steering, the matching design of rear wheel steering mechanism isproposed. To make the rear wheels have steering function, this study has modified therear suspension of test car, finished the parts processing and finite element analysis forthe key parts. According to the needs of control to the4WS, a circuit board of controlsystem based on ARM7series of LPC2148has been developed, which has completedthe schematic diagram, PCB design, circuit board welding work and hardwaredebugging. The paper has established a three degrees of freedom dynamic model andkinematic model of the rear wheel steering system for the four-wheel steering vehicle,Simulinked the Four-Wheel steering model at high speed and the rear wheel steeringcontrol. Studied the multi-mode control strategy for4WS, and found the best angle ofrear wheel at the specified speed and front wheel steering angle and the PID parameters，and designed the control method based on the simulation. The program has transplanteduC/OS-II real-time operating system, and divided the system task and design, whichintroduced the tasks scheduling and the priority and execution cycle of each task indetail, gave the running flow chart and related program design of the task. The articlehas mainly introduced the acquisition signal task with the sensor, motor control tasks,the execution algorithm of SD card storage. It has explained in detail of the motorcontrol task, and emphasized the RS485communications between the controller anmotor drive function, specific to the work process and communication protocol, inaddition, the module program debug and related experiment has been done.