Research Of Handling And Stability Control For Four-Wheel-Drive Electric Vehicle

Four-Wheel-Drive electric vehicle(FWEV)has a lot of advantages compare to the traditional vehicle.It can omit the driving mechanism between power units and driving wheels,so that it can improve the transmission efficiency,save the space of chassis and increase the vehicle controllability.Because of these advantages,this kind of electric vehicle will be the development trend of new energy vehicles.In order to give play the advantages of FWEV,it is meaningful to propose a kind of control strategy to distribute the driving force to four driving wheels reasonably.In recent years,many colleges and companies have researched the driving force distribution control of FWEV,but most of them only considered the vehicle dynamics and didn't consider the recognition of driver's intention.Even if some researchers have focus on how to identify the driver's intention,they didn't consider how to use the results of recognition to improve the control strategy.This paper proposed a driving force distributing control strategy which considered the drive's intention to improve the stability of FWEV.This control strategy was based on the direct yaw-moment control(DYC)and it was consisted of three parts.It distributed the driving force to each driving wheel through monitoring the yaw rate and sideslip angle of vehicle.Driver's intention recognition model was built through fuzzy logic and neural network.It can recognize the accelerated intention and steering intention and correct the driving force distributing control strategy to improve the dynamic performance,flexibility and stability of vehicle.The co-simulation platform was consisted of control strategy and vehicle model.The control strategy was built using MATLAB/Simulink and the vehicle model was built using CarSim according to the parameters of a real test vehicle called "New Fire?".Co-simulation was conducted under different driving conditions to confirm the correctness and control effects of driving force distributing control strategy and driver's intention recognition model.A rear-wheel-independent-drive vehicle("New Fire ?")was reformed to a FWEV ("New Fire ?")for confirming the control effects on the real vehicle.The engine was replaced by battery and some connecting pieces were designed for fixing the in-wheel-motor and controller.The CAN communication protocol has been debugged so that the motor can work with the control strategy.Based on the simulation,rapid control prototype(RCP)test was taken.The vehicle virtual controller was built with NI cRIO and the control program was written by LabVIEW.The results show that this control strategy can distribute the driving torque to the driving wheel reasonably according to the yaw rate and sideslip angle,so that it can improve the stability of vehicle.In addition,the results of RCP test are similar to the results of simulation.So it can be proved that the vehicle model in CarSim can take place of the test vehicle,and can be used to test the control effects in some conditions more complicated.