Stable adaptive control for nonlinear multivariable systems with a triangular control structure

A stable adaptive controller is developed for a class of nonlinear multivar iable systems using nonlinearly parametrized function approximators. By uti lizing the system triangular property, integral-type Lyapunov functions are introduced for deriving the control structure and adaptive laws without th e need of estimating the "decoupling matrix" of the multivariable nonlinear system. It is shown that stability of the adaptive closed-loop system is g uaranteed, and transient performance is analytically quantified by mean squ are and L-infinity tracking error bound criteria.