Based On The Traditional Front Steering Structure Of Four-wheel Steering Control Research

The technology of four-wheel steering is to control the input of the rear angle withthe collected information of vehicles when running. The technology had graduallybecome one of the important research focus on the modern automobile since thetechnology can improve the handling stability and maneuverability on vehiclesignificantly. In the near future, the four-wheel steering system will be more and morewidely used in all kinds of cars, and in the article, it mainly studied the steering mode ofthe four-wheel steering, which has a certain practical significance in promote thedevelopment of the four-wheel steering.In the paper, it established a SIMULINK model of three-degree-of-freedom (lateral,yawing and roll)linear system of four-wheel steering in MATLAB, described the designprocess of steering mode controller about the4WS system, and it took use of the part offuzzy model to set up the judge mechanism of the steering mode in four-wheel steeringsystem, deduced and established the resolve model of the rear wheel angle in differentsteering modes, combined it with the switch mode controller, tested and verified therationality of the steering mode control strategy by simulation.In order to verify the steering mode control strategy further, a car Honda accordCB3had been transformaed into four-wheel steering and a hardware platform of thecontroller had been designed, that had been composed a experience platform of4WSsystem in car.In the paper it expressed the detail idea to realize the control of the steering modeon4WS system, which concluded the scheme of steering swich4WS, the scheme ofdrive moto control both under the2WS and4WS, the signals collection of varioussensors and the storage of the data, all have been described in the form of flow chart.Considering directly run the whole control system with a bare-metal could have somedisadvantages, the experiment transplanted the μC/OS-II real-time operating system,divided the task, allocated the priority in detail, and realized the control strategy byprogramming on the LPC2148.In the part of real experiment, the article had decribed the control scheme of thesteering mode under the condition of realistic test car and the verified experiment. First,test the steering response and the angle on both of the front and rear wheels, which canmake sure the coordinate of the sofeware and hardware control platform. Second, sincethe real test car which had beed transplanted only in the part of rear wheels, the frontwheels was still in the law of geometric constraints under2WS, based on that the article deduced the relationship of the four wheels. Finally, the paper had designed threegroups of experiments to verifiy the steeing mode control of the4WS system under thedifferent conditions of the vehicle speed and the angle of outside front wheel.