Prescribed Performance Fault-Tolerant Control of Nonlinear Systems via Actuator Switching
Chen-Liang Zhang, Ge Guo
Abstract
This article investigates a prescribed performance control (PPC) problem of nonlinear strict-feedback systems subject to actuator faults. By introducing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ln$</tex-math></inline-formula> -type performance functions, a constraint of output tracking error is established to prescribe the performance. Via the use of mapping and barrier error transformations, the constraint-handling issue is converted into a stabilization one of unconstrained variable. Then, an adaptive controller involving a fuzzy logic system to approximate the unknown nonlinearity is devised to stabilize the transformed variable, resulting to a universal PPC algorithm that applies to all types of asymmetric prescribed performance requirements. To prevent such requirements from being violated due to actuator faults, a novel dynamic redundancy mechanism is incorporated to implement the performance monitoring and switching from the faulty actuator to a healthy one. Two simulation examples are presented to verify the effectiveness and superiority of the proposed scheme.