Skid steering-based control of a robotic vehicle with six in-wheel drives

This paper describes a driving control algorithm based on a skid steering for a robotic vehicle with articulated suspension (RVAS). The RVAS is a kind of unmanned ground vehicle based on a skid steering using an independent in-wheel drive at each wheel. The driving control algorithm consists of four parts: a speed controller for following a desired speed, a lateral motion controller that computes a yaw moment input to track a desired yaw rate or a desired trajectory according to the control mode, a longitudinal tyre force distribution algorithm that determines an optimal desired longitudinal tyre force, and a wheel torque controller that determines a wheel torque command at each wheel in order to keep the slip ratio at each wheel below a limit value as well as to track the desired tyre force. Longitudinal and vertical tyre force estimators are required for the optimal tyre force distribution and wheel slip control. A dynamic model of the RVAS for simulation study is developed and validated using the vehicle test data. Simulation and vehicle tests are conducted in order to evaluate the proposed driving controller. It is found from simulation and vehicle test results that the proposed driving controller provides a satisfactory motion control performance according to the control mode.