A Time-varying Cascaded Design for Trajectory Tracking Control of Nonholonomic Systems

This paper deals with the tracking control problem for a general class of nonholonomic dynamic systems with reference signals that may exponentially decay. By introducing a time-varying coordinate transformation and using the cascade-design approach, smooth time-varying controllers are constructed, which render the tracking error dynamics globally K-exponentially stable. Obtained result shows that the popular condition of persistent-excitation or not converging to zero imposed on the reference signals is not necessary even for the globally K-exponential tracking of nonholonomic systems. Application to the tracking control of an underactuated surface vessel validates the effectiveness of the proposed method.