Development of Torque Control Algorithm for Skid Steering Six Wheel Drive with In Wheel Motors

Abstract

In skid steering vehicle all the wheels are non-steerable and the vehicle is turned as a result of the application of differential torque to wheels on opposite sides. For better control and performance the correct torque command should be given to each wheel so that the skid steering vehicle follow the driver intended path. The use of electric motors in each wheel instead of mechanical drives is more advantageous regarding performance because of very short response time and possibility of independent torque control. In this study first we modelled the Six Wheel Skid Steering Vehicle having 6 in-wheel motors in Simulink?? then we proposed Torque Control Algorithm. This control algorithm consists of two levels. The upper control uses two PID controllers to achieve the desired velocity and desired yaw rate which generates the torque commands for each wheel based on the desired yaw rate and desired velocity. At the lower level slip ratio controller is applied to each wheel independently as minor loop to prevent slipping. The torque commands will be overwritten of any of the wheels start slipping. This algorithm is applied to Driver-In-Loop mode using the developed 6x6 model and simulations are carried out using MATLAB Simulink??. These results show that this control algorithm can be use effectively in controlling the skid steering vehicle on different road conditions.