Intelligent Fault Tolerant Control For A Class Of Uncertain Nonlinear Systems

In this thesis,for several class of nonlinear multi-agent systems with actuator failures,based on the fuzzy adaptive backstepping design method,fault-tolerant control principle and multi-agent cooperative control theory,the problem of the adaptive fuzzy fault-tolerant control design method and the stability analysis of control systems are solved.The main works are as follows:(1)The adaptive fuzzy fault-tolerant control problem is studied for a class of multi-agent nonlinear fault systems with single ‘leader' and multi ‘followers',the controlled systems contain the unknown nonlinear functions,unknown control direction,actuator bias and gain faults as well.In the control design,the controlled system with unknown function and unknown control direction are firstly processed by using the fuzzy logic system and Nussbaum gain function theory,respectively;then an adaptive fuzzy fault-tolerant control method is proposed.based on the adaptive backstepping design method and fault-tolerant control theory.By using the Lyapunov function stability theory,it is ultimately proved that all signals in the closed-loop system are uniformly bounded,and the outputs of all ‘followers' are synchronized with the output of the ‘leader'.The simulation results are provided to further validate the effectiveness of the proposed control scheme.(2)the adaptive fuzzy fault-tolerant control problem with prescribed performance is studied for a class of multi-agent nonlinear fault systems with single ‘leader' and multi ‘followers',and the controlled systems contain the unknown nonlinear functions,unknown control direction,actuator bias and gain faults as well.In the control design,the controlled system with unknown function and unknown control direction are firstly processed by using the fuzzy logic system and Nussbaum gain function theory respectively;then an adaptive fuzzy fault-tolerant control method with actuator fault suppression is proposed.based on the adaptive backstepping design method and prescribed performance control theory.By using the Lyapunov function stability theory,it is ultimately proved that all signals in the closed-loop system are uniformly bounded,the synchronization errors are always within the specified boundary as well.The simulation results are provided to further validate the effectiveness of the proposed control scheme.(3)The adaptive fuzzy output constraint fault-tolerant control design problem is studied for a class of multi-agent nonlinear faulty systems with multi ‘leaders' and multi ‘followers',the controlled systems contain the actuator lock-in-place and loss of effectiveness faults.In the control design,firstly fuzzy logic system is used to approximate unknown nonlinear function in controlled system.Secondly fault compensation method is designed.Then based on the backstepping design mehod and the barrier Lyapunov function stability theory,an adaptive fuzzy output constraint fault-tolerant control design method is proposed.By using the Lyapunov function stability theory,the stability of the closed-loop system and the convergence of the tracking error are proved ultimately.The simulation results are provided to further validate the effectiveness of the proposed control scheme.