Dynamic modelling and experimental validation of a skid-steered vehicle in the pivotal steering condition

The pivotal steering ability of a skid-steered vehicle is an important advantage compared with the steering ability of an Ackermann steered vehicle. In the pivotal steering condition, the strong non-linearity of the properties of the tyres makes prediction of the dynamic modelling and the performance difficult. For this purpose, this paper proposes an experimentally validated dynamic model to describe the motion of a skid-steered vehicle in the pivotal steering condition. The mechanical analytical model of the tyres was constructed on the assumption of an 'elliptical parabolic' contact pressure distribution. The dynamic model has nine degrees of freedom, including the longitudinal motion, the lateral motion and the yaw motion of the body and also the rotation of the wheels; the motor saturation is also considered. The analysis and experiments were based on a specific 6 × 6 unmanned skid-steered vehicle which is driven by six independent in-wheel motors, and the driving control algorithm of the vehicle was also described. By comparing the results of experiments and simulations, it was shown that the dynamic model provided an accurate prediction of the performance.