Adaptive actuator failure compensation for nonlinear systems with aircraft control application

In a control system, actuator failures may cause significant damaging effect on system performance or even catastrophic accidents. Actuator failure accommodation is very important especially for life critical systems. Two adaptive backstepping control schemes aimed to accommodate actuator failures, which are uncertain in time, pattern and value for nonlinear systems are studied. Firstly, a basic design scheme based on existing approaches is considered. However, when actuator failures occur, transient performance of the system cannot be adjusted through changing controller design parameters. Then a new controller design scheme based on a prescribed performance bound (PPB) which characterizes the convergence rate and maximum overshoot of the tracking error is discussed. It is shown that the tracking error satisfies the prescribed performance bound all the time. Simulation studies also verify the results that the PPB based scheme can improve transient performance compared with the basic scheme, while both ensure stability and asymptotic tracking with zero steady state error in the presence of uncertain actuator failures.Master of Science (Computer Control and Automation