Research On Control Strategy Of Four Independent Steering For Electric Vehicle

The 4WIS (four wheel independent steering by wire) electric vehicle is a new type of vehicle receives wide attention and in-depth study because of its independently controlled by the steering angles of the four wheels, which can improve the stability and maneuverability of the vehicle. As the core of the four wheel independent steering by wire, steering control has become a hot research topic. Based on the zero sideslip angle control as the goal, aiming at four steering motors coordination control problem of electric vehicle, proposing the 4WIS multi motors c,oordinated control strategy based on rotate speed as control variable, to achieve reasonable distribution of rotate speed of the stepper motor, the main research contents are as follows:(1)The research status of the 4WIS electric vehicles are reviewed, expounds the significance of the establishment of new steering structure, large angle steering four bar linkage mechanism kinematics model, to verify the feasibility of mechanism in Solidworks, the vehicle in situ static steering as the steering resistance torque to select the steering motor, ensure the feasibility of 4WIS electric vehicle steering.(2) The paper introduces the allocation strategy of 4WIS electric vehicle when the steering mode is different, analyzes the principle of stepper motor speed control of the trapezoidal velocity curve; proposing the multi-motors coordinated control strategy of speed control with fixed stepper motor acceleration and deceleration time; Simulation model is built by MATLAB/Simulink according to vehicle dynamics and rotational speed control of the two-phase hybrid stepper motor combined, the simulation results show that the control strategy can realize the coordinated control of four stepper motors with different driving conditions,which proves the feasibility and effectiveness of this strategy.(3) On this basis to TMS320F28335 DSP as the control core, set up 4WIS electric vehicle steering control experiment platform. Research on UI SimpleCAN protocol to realize network communication between the central controller and stepper motor controller, the speed and angle displacement data of the steering motor are collected and processed, experimental results and simulation results show the feasibility of the control strategy.