Dynamic modeling and trajectory tracking control of unmanned tracked vehicles

Abstract

Tracked vehicles have inherent advantages over wheeled vehicles, as the former provide stable locomotion on loose and uneven terrain. However, compared with the latter, the slippage generated due to the complex, nonlinear track-terrain interactions during skid-steering to follow a curve, brings about difficulties preventing the accurate prediction of their motions. The key to improving the accuracy of trajectory-following is the “proper” motion control methodology that can accurately factor-in the slippage behavior. In this paper, the authors propose a novel approach to the dynamic modeling and motion control of tracked vehicles undergoing skid-steering on horizontal, hard terrain, under nonholonomic constraints. Due to the skew-symmetry property of nonholonomic mechanical systems, the control methodology is established using the backstepping method based on a modified Proportional–Integral–Derivative (PID) computed-torque control. A key element in the control strategy proposed here is the reliable estimation of the pose – position and orientation – of the vehicle platform and its twist—point velocity and angular velocity. It is assumed that the vehicle is suitably instrumented to allow for accurate-enough pose and twist estimates. Validated via a numerical example, the proposed controller is proven to be effective in controlling an unmanned tracked vehicle.