Adaptive output tracking of nonlinear systems in general lower-triangular form

This paper investigates the problem of adaptive output tracking for a class of nonlinear systems in general lower-triangular form, which not only encompasses some important lower-triangular systems, but also expands the normal lower-triangular form to a more general case. The systems are classified into two cases: polynomial lower-triangular form and function lower-triangular form. Based on Lyapunov stability theory and modified power integrator approach, the adaptive controllers are designed to ensure the global stability property and practical output tracking. Examples and simulations are provided to show the effectiveness of design method.