摘要：In this thesis, the robust fault-tolerant flight control design approaches for a small unmannedvehicle are investigated.Based on Safety, reliability and acceptable level of performance ofdynamic control systems are the major keys in all control systems especially in safety-criticalcontrol systems.A controller should be capable of handling the disturbance and uncertaintiesimposed to the controlled process.The main works are listed as follows:
(1) Study of the actuator fault detection and isolation.Fault observer design for the UAV'sActuator System.We design a set of observer-based residuals to generate the residuals whichare sensitive to the faults, and the isolation of the faults.Scheme for the detection andisolation of actuator fault in linear systems is proposed.An unknown input observer isconstructed to generate residual signals which will deviate in characteristic way in presenceof actuator faults, in such a way the transfer from the disturbances to the residuals is zero andthe transfer from the faults to the residuals allows fault isolation.
(2) Robust PID controller design for UAV system.Describe the PID controller design foran UAV flight control system.We will focus on these main points: pole placement theory,the control design and stability response, model reduction techniques to enhance theperformances and robustness of PID controller.The PID-based control design for UAV's flightcontrol system is used to present the control design for the attitude loop which can make theflight dynamics to track a given reference.The design scheme provide pitch design of anUnmanned Aerial Vehicle
(3) Fault tolerant tracking control design with transient performance deals with a robust
prescribed performance control (PPC) technique for nonlinear UAV systems with unknowndynamics and uncertainties.Prescribed performance function (PPF) is integrated into thecontrol design, such that both the steady-state and transient control performance can bequantitatively studied and strictly guaranteed.For any a priori known initial state condition,bounded signals in the closed loop, as well as prescribed performance for the output trackingerror, we propose a systematic control design procedure, where the proportional-like controlsare obtained by using the transformed tracking errors with PPF.Eventually extensivesimulations are conducted based on linear and nonlinear UAV to validate the convergenceperformance and the robustness of the investigated control method.