Study On Differential Assisted Steering And Torque Coordinating Control Of Four In-wheel Motors Driven Electric Vehicle

In-wheel motors driven electric vehicles are widely concerned and researched by scholars both at home and abroad because of simple vehicle structure,active chassis control,and the obvious advantages in the convenience of manipulation and wonderful future prospects.The control of wheel speed and torque is becoming a key issue when turning,because of the vehicles driven by multiple independent motors.At the same time,the stability and safety of vehicle seriously affected by the problem of partial motor failure.In order to solve these problems,based on the self-made experimental prototype vehicle,the differential assisted steering and torque coordinating control of four in-wheel motors driven electric vehicle are researched in this paper,and the main contents are as follows.(1)A differential steering control system is designed by the SMC(sliding mode control)theory.The if-else statement is used to supplement the system so that it can solve the problem of arbitrary steering of electric vehicles.The simulation of snake driving and comparison experiment of different control methods are completed.The simulation results show that the control system is able to realize the differential speed control of the wheels under the steering condition,and it does better than the PI control system.(2)The vehicle state equations of actual and expected modes are established.The controller of torque distribution is designed by applying the principle of SMC,and the snake driving simulation test is also carried out.The results show that the torques of four wheels are well controlled in the steering process,which can ensure favorable stability for the vehicle.In addition,the torque coordination control strategy of single motor failure and fault tolerance is formulated,and simulation analysis is carried out.(3)Sharp and continuous steering handling stability simulation are done.The handling stability simulation of the prototype vehicle is analyzed based on the 7-dof model.It can be seen from the simulation results that the prototype vehicle model owns remarkable stability.Then,the 3D model and entity model of prototype vehicle are designed.With the DSP as the control unit,a driving test of prototype vehicle is carried out.The test results show that the designed system can be applied to the actual prototype car and enable it to implement steering.