Two New Nonlinear Modeified Adjustment Laws for Variable Structure and Compound Robust Adaptive Control. Higher Relative Degree Case

摘要

An extension of two modified update laws for variable structure and compound adaptive control is presented in this paper. The extension concerns variable structure and compound adaptive control of plant model with relative degree greater than one. For that an augmented error synthesis is need as an identifier error. The proposed modifications are presented at the level of parameter update laws, in both components of compound control. The closed loops have well robustness qualities to bounded adaptive control a k-sigmoid function has been used in parameter update laws for allleviating chattering. No any prior information is need about the norm of the controller parameters or the upper bound of the disturbances. Lyapunov functions are used to proof global stability of the adaptive loops. Simulation results, for an unstable plant model of relative degree two, are presented.