| All kinds of electric vehicles have become the focus of research and development in various countries.The four wheel independent drive electric vehicle,the four wheel drive force can be independently controlled,and then it can make differential steering.Therefore,it has a smaller turning radius than the traditional mechanical steering vehicle,and the operation is more flexible,lightweight and more stable.The science and Technology Department of Liaoning Province Natural Science Foundation Project "four wheel independent drive electric vehicle based on EPS control research,conducted with electric power steering control,differential power steering control and differential power compensation control of four wheel drive electric vehicle research,research contents include the following aspects:(1)Modeling of four-wheel independent drive electric vehicle with EPS.Analysis of wheel motor system and electric power steering system(Electric Power Steering,referred to as EPS),the model of electric vehicle components and working principle,wheel motor model,electric power steering model is built in Matlab/Simulink module,and embedded into the Carsim vehicle model and vehicle model of four wheel independent drive electric vehicle.(2)EPS and differential power control.Under the precondition of satisfying the general vehicle’s driving stability,according to the basic requirements of the power assist characteristics,a series of basic control strategies such as basic power control,torque differential control and so on are adopted in the electric power steering control strategy.The working principle of differential power steering is analyzed.For the four wheeled independent driving electric vehicle,the four wheel drive torque can be allocated freely,and additional current is applied to the driving motor of the steering wheel,so that it has the function of differential steering.(3)The auxiliary power compensation control under the combined control of EPS and differential power.The driver’s requirement for the steering operation of the general vehicle is analyzed(i.e.,at low speed,turning light;at high speed,stable driving).Considering the inadaptability of the driver because of the discrepancy of the operation,it causes the operation error and is dangerous.In order to reduce the adverse effects of operation on the driver,compensate for the difference between the four wheel independent driving electric vehicle with differential steering function and the general vehicle operation,and build the corresponding differential power steering compensation control in the Matlab/Simulink module.(4)EPS and differential power control hardware are used in the loop experiment.The existing automobile driving simulator hardware in the loop test-bed is selected,and the corresponding typical working conditions are selected to verify the electric power steering control,differential steering control and differential power steering compensation control.Experimental results show that differential power steering can help vehicle reduce steering radius,and compensate control at lower speed helps vehicle further reduce turning radius and increase vehicle stability at high speed. |
