Coordinated Control Of Differential And Assistant Steering For Electric Vehicle Driven By Dual In-Wheel Motors

For the purpose of reducing the exhaust emission and the dependence on non-renewable resource, new energy vehicle has got much attention. Compared with the hybrid electric vehicle, plug-in hybrid electric vehicle and pure electric vehicle,the in-wheel motor drive electric vehicle bas unique advantages in dynamic control.In this thesis, the differential and assistant steering coordinate control strategy of the electric vehicle driven by dual in-wheel motors has been researched, providing the research basis for the multi-dynamic control of the four in-wheel motor drive electric vehicle.The principle of electric differential control and assistant steering control of in-wheel motor drive electric vehicle has been analyzed. Based on the software of Car Sim and Simulink, the co-simulation vehicle model has been build. What’s more,the prototyping four in-wheel motor drive electric vehicle has been build, which is equipped with current sensor, voltage sensor, steering wheel torque and angle sensor and wheel speed sensor. The inertia navigation system is used to monitor the vehicle attitude cooperated with the high precision GPS. The vehicle control system is build based on the rapid prototyping and the vehicle CAN bus is set up to transfer data.Also, the co-simulation vehicle model has been verified through the prototyping vehicle road test.The vehicle yaw rate transmit function of steering wheel angle input at vehicle stable steering condition has been researched and the sliding model control has been used to design the electric differential control strategy, which is set to follow the ideal vehicle yaw rate. On the other hand, the PID control has been chosen to design the assistant steering control strategy to realize assistant steering, which is set to follow the ideal steering wheel torque What’s more, in the purpose of realizing electric differential and assistant steering with the same actuator, the influence factors of both electric differential and assistant steering have been analyzed and the coordinate control strategy based on the weight function of differential control and assistant steering control has been designed according to the vehicle speed. The vehicle modelsimulation and prototyping vehicle road test have been done. The simulation and road test result show that the vehicle state is stable and also there exists some assistant steering efficient under the control of the differential control system at relatively high vehicle speed. What’s more, the assistant steering system can decrease the driver steering wheel torque effectively and the vehicle state keeps stable at relatively low vehicle speed. At last, the weight coefficient of the coordinate control system changes follow the vehicle speed and the differential and assistant steering performance is well during all the speed area.