Stability Control Strategy Research And Experimental Verification Based On Four Wheel Steering Control By Wire

In recent years,with the continuous development of electronic technology,four-wheel steering(4WS)and steering by wire(SBW)technology has become the research hot spot of the automobile steering system.4WS technology is the most effective active chassis technology to improve vehicle handling stability,while SBW is the development trend of four-wheel active steering,it removed the mechanical connections between steering wheel and steering wheel parts,completely instead by the signal line and controller,and through reasonable control methods to allocate the front and rear wheel angle,so as to realize intelligent control.In this paper,the control strategy of four wheel steering by wire is studied deeply.In detail explained the process of establishing the CarSim multi-degree-offreedom nonlinear vehicle model?the 4WS two degrees of freedom vehicle model and the 4WS three degrees of freedom vehicle model,and the simulation output response of the steering wheel angle step input mode of the 4WS two degrees of freedom vehicle model?the 4WS three degrees of freedom vehicle model and the CarSim vehicle model are compared by MATLAB/simulink.Results show that the results of the 4WS two degree of freedom vehicle model and the 4WS three degree of freedom vehicle model are very close to the CarSim vehicle model,which provides a reliable theoretical basis for the design of vehicle controller.Research of the concrete derivation process of the fuzzy control method to design the variation transmission ratio and four wheel steering by wire optimal control algorithm,and simulates the 4WS variable transmission ratio optimal control vehicle model by MATLAB / simulink.The simulation results show that the four wheel steering by wire vehicle variable transmission ratio optimal control is realized in that under the premise of guarantee the car will not instability,not only possess the good flexibility at low speed and steering stability at high speed of the vehicle ideal performance,but also can guarantee under the various conditions of sideslip angle is minimizing and the Yaw rate overshoot is decreased and the settling time is shorten in transient state,ensure the vehicle driving state and safety.In order to solve the problem that four wheel steering by wire vehicle might lose its handling stability when it suffers lateral interference,the improved sliding mode 4WS controller? the double-line simulation condition and the single-point preview driver model are designed,and the control method is simulated by the driver-vehicle-road closed-loop control.The results show that the control method can effectively track the given double-line travel condition and has strong robustness to the lateral disturbance.It can be used to study the vehicle handling stability problem when the vehicle is affected by lateral interference.Finally,studied and elaborated the hardware and software design of the four wheel steering by wire vehicle.