Global κ-exponential Tracking Control of Nonholonomic Systems in Chained-form by Output Feedback

The output tracking control problem of nonholonomic chained form systems is studied in this paper and global κ-exponential output trackers are presented without persistent excitation or not-converging to zero on reference trajectories. First, a time-varying coordinate transformation is introduced to avoid manipulating exponentially converging signals. Then, with the help of theory of cascaded systems and linear perturbed systems, global κ-exponential output trackers are successfully obtained. A new feature of the proposed controller is that the output tracking control problem of nonholonomic chained form systems is also resolvable without the popular condition of persistent excitation or not converging to zero on reference signals in the previous works. The proposed method is demonstrated and discussed by means of nonholonomic mobile robots and cars with one trailer.