Robust Trajectory Tracking Control Design for Nonholonomic Mobile Robot (NMR)

This paper addresses the problem of trajectory tracking for kinematic model of unicycle-type nonholonomic mobile robot. These robots are difficult to stabilize and control due to their non-integrable constraints. Due to this problem, it is difficult to establish a systematic model for tracking. In this paper, the proposed controller is defined in a two-step process. First, a robust state feedback point-to-point stabilization control is designed using Sliding Mode Controller (SMC). In the second step, the controller is modified so as to address the tracking problem for the constant as well as time-varying reference trajectories. The proposed control scheme is shown to provide for desired robustness properties in presence of the parametric variations, in the region of interest. The state-feedback control scheme is then extended to output feedback by incorporating a High Gain Observer. With the help of Lyapunov analysis and appropriate simulations, it is shown that the proposed output feedback control scheme achieves the required control objectives and provides for the desired performance in the presence of parametric variations.