Indirect adaptive fuzzy prescribed performance control of feedback linearisable MIMO non-linear systems with unknown control direction

摘要

An indirect adaptive fuzzy prescribed performance control scheme is developed for a class of uncertain multi-input and multi-output feedback linearisable non-linear systems with unknown control direction and external disturbances. The properties of symmetric matrix and hyperbolic tangent function are exploited and the predefined tracking performance boundary is used to design the adaptive fuzzy prescribed performance controller, which can avoid the possible singularity problem and calculating the inverse of matrix. A robust controller equipped with a Nussbaum-type function is constructed to compensate for the lumped errors and solve the unknown control direction problem. The proposed scheme guarantees that all the signals in the resulting closed-loop system are bounded and that the tracking errors converge to a small residual set with the prescribed performance bounds. Simulation results are used to demonstrate the effectiveness of the proposed approach.