A cascade controller for tracking and stabilization of wheeled mobile robotic systems

A wheeled mobile robotic system (WMR) is a kind modular robotic, nonlinear and the system subjected to nonholonomic constraints. It is impossible to obtain an exact dynamics model due to unknown parameters, unpredictable and irregular features, external disturbance. This paper proposes an adaptive robust controller to guide WMR to follow the desired trajectory. The cascade control system is applied and the influence from external disturbances, parametric uncertainties in WMR are compensated by the robust-adaptive nonlinear control law at inner loop based on certainty equivalence adaptive technique. The asymptotic stability of the whole system is analyzed by using Lyapunov theory showing that asymptotic convergence of tracking errors to the origin in presence of uncertainties and external disturbances. The simulation results demonstrate the good performance of the proposed controller for trajectory tracking.