Differential Drive Collaborative Steering Control Of Articulated Vehicles With Four Motor-driven Wheels

At present, with the intensification of environmental issues and energy crisis HEV and EV have got widely development.The articulated vehicles with four motor-driven wheels also have been extensively developed.Hydraulic steering system which had the problems of high energy consumption and slow response was commonly used by articulated vehicles.To solve these problems a differential drive collaborative steering control algorithm which exerted different drive torque to the two front wheels was proposed in this paper.The dynamic equations of the vehicle,the kinematics of articulated steering and steering torque resistance were analyzed in theory based on the research actuality of articulated steering vehicles by this paper.The vehicle model has been built with ADAMS and the hydraulic steering system with AMESim to carry out the co-simulation,the experimental articulated wheelloader driven by hub motors has been constructed to verify the viability of differential drive collaborative steering. Simulation and test results show that it was effective to improve the velocity of steering response and reduce the energy consumption of hydraulic steering system by exerting different drive torque to the two front wheels when cornering.Then the differential drive collaborative steering control algorithm was built with Simulink based on fuzzy self-tuning PID controlling.Also the vehicle model and the hydraulic steering syetem were imported to Simulink to verify the control algorithm.The input signals of the differential drive collaborative steering control system were the difference and the change rate of this difference between the desired yaw velocity and the actual yaw velocity.The output signal was the differential torque exerted to the two front wheels.Then the output torque was imported to the motor controller.The motor controller caltulated the current wheel slip rate and export them to every drive wheel to keep the slip rate in optimal slip ratio.Finally the simulation tests for the differential drive collaborative steering control strategy are conducted,and the results proved it was effective to improve the velocity of steering response and reduce the energy consumption of hydraulic steering system by exerting different drive torque to the two front wheels when cornering.