Global output-feedback path tracking of unicycle-type mobile robots

We present an output-feedback controller that forces the output (position and orientation) of a unicycle-type mobile robot to track a predefined path. A coordinate transformation is first derived to cancel the velocity quadratic terms. An observer is then designed to globally exponentially/asymptotically estimate the unmeasured velocities. The controller synthesis is based on Lyapunov's direct method and the backstepping technique. Our proposed controller works for both internally damped and un-damped cases. Simulations illustrate the soundness of the proposed controller.