Research On Electrcal Differenntical Of Four Wheel Independent Drive Vehicles

In order to deal with the global Energy crisis and environmental pollution,distributed electric vehicles with independent four-wheel drive have gradually become one of the research hotspots in the electric vehicle industry.The output control of four-wheel independent distributed drive electric vehicle to the driving wheel is completely different from that of traditional Internal combustion locomotive,so it is necessary to study the problem of four-wheel shaftless electronic differential control.This project conducts research from the following aspects:The vehicle model with seven degrees of freedom and its simplified model are established and modeled in Simulink,which provides the basis for the research of electronic differential.A vehicle state parameter observer based on extended Kalman filter is established to estimate the key state parameters of the vehicle in real time,such as longitudinal speed,yaw rate and so on.The simulation results show that the observer can accurately estimate the parameters under the test conditions.A layered electronic differential control method is designed.The lower layer is the fourwheel differential planning module,aiming at reducing drag between wheels.Based on the quadratic programming theory,combined with the influence of tire lateral force on the steering differential yaw moment of the whole vehicle,the four-wheel differential planning is carried out with "tire load rate" as the optimization objective,and the inter wheel differential strategy based on slip rate is designed as the supplementary control method when the lateral acceleration is too large;The upper layer is the expected generalized force tracking module.Aiming at the vehicle stability,the parameter self-tuning sliding mode control method proposed in this paper is used to calculate the generalized force of the plane motion target of the whole vehicle based on the proposed inter axle differential parameters and inter wheel differential parameters.The joint simulation experiment based on Car Sim/Matlab and the real vehicle experiment based on distributed drive electric vehicle platform show that under different working conditions,the parameter self-tuning sliding mode control algorithm proposed in this paper can make the increasing trend of vehicle centroid sideslip angle and yaw rate smaller and the falling response faster;At the same time,the differential programming algorithm proposed in this paper can also keep the "tire load rate" in a low range,which proves that the proposed algorithm can reduce the drag between wheels while maintaining the vehicle stability.