Research On Stability Control Of Four Wheel Independent Drive Electric Vehicle With Driver-In-Loop

Under the double oppression of energy crisis and environmental pollution,the countries around the world are promoting and developing electric vehicles vigorously.Compared to other forms of electric vehicles,the four wheel independent drive electric vehicle(4WID-EV)has become a research hotspot in the world due to its unique structure and performance.In this paper,the 4WID-EV is taken as the research object and considering the influence of driver-in-loop,the handling stability of the 4WID-EV which is running is studied and analyzed.First of all,according to the 4WID-EV structural characteristics and traditional internal combustion engine modeling experience,the vehicle dynamic simulation model is established in MATLAB/Simulink software,which includes body dynamic model,“Magic Formula” tire model and wheel motor model etc..Secondly,this paper introduces research status of directional control driver model and related theory of the preview optimal curvature driver model.Based on the disadvantage of traditional driver model-without high control accuracy,the fuzzy control theory and PID control theory are combined to apply to the driver model and a new directional control driver model was raised in this paper,and the reliability of the designed driver model is verified by the snake-form test.Then,this paper analyses the reasons of losing handing stability minutely,presents several measures to improve the vehicle handling stability,and selects DYC as the control method to improve the handling stability.Simultaneously,a hierarchical control strategy is proposed based on the idea of hierarchical double-layer architecture,the upper controller is a yaw rate and sideslip angle joint controller,which adopts the fuzzy sliding mode control strategy as closed-loop feedback controller with choosing the yaw rate and sideslip angle as the control variables based on fuzzy and sliding mode control theory to calculate the yaw moment.The lower controller is a yaw moment optimal distribution controller,which selects the least quadratic sum of the four tire longitudinal utilization rate as the objective function and chooses the adhesion characteristics of road surface and the torque peak of motor as the constraint conditions,utilizes the quadratic programming to allocate the additional yaw moment to each hub motor,the vehicle stability control of 4WID-EV is realized finally.Finally,based on the driver-vehicle simulation platform which constructed by4WID-EV dynamics model,driver model and stability control strategy,the three typicalsimulation conditions which contain the J-Turn,Fishhook and snake-form test is chosen to do vehicle handling stability simulation analysis.The simulation results show that the handling stability control based on driver-in-loop can not only improve the vehicle trajectory tracking ability,but also improve the vehicle handling stability and driving safety.