A new approach to global asymptotic tracking for a class of low-triangular nonlinear systems via output feedback

In this note, we address the problem of global output feedback tracking for a class of low-triangular nonlinear systems. Instead of using backstepping approach, we propose a novel dynamic gain scaling technique to design the output feedback controller. With a change of coordinates, a linear-like controller is constructed, which avoids the repeated derivatives of the nonlinearities depending on the observer states and the dynamic gain in backstepping approach and therefore, greatly simplifies the design procedure. It is proved that by using the new technique, global stability of the closed loop system can be guaranteed and the output tracking error converges to zero exponentially.