Satellite Attitude Fault Tolerant Control Based On LPV Model

Faults of attitude control systems especially actuators and sensors occur more often comparing with other satellite on-orbit faults.It is meaningful to study satellite attitude fault tolerant control.The dynamics model of this problem is highly nonlinear and the system parameters vary in a large range.Linear Parameter Varying(LPV)system reflects time varying and nonlinear characteristics by varying parameters and it is suitable for a time-varying system with parameters changing in a large range.In this paper,robust gainscheduled fault tolerant controllers based on LPV model are designed for satellite attitude control system with the actuator multiplicative faults.The main contents include the following sections.The satellite attitude dynamics system is built with the dynamics and kinematics equations.According to the characteristics of the actuator faults,the faults are classified and different fault models are set up.Robust gain-scheduled PID fault tolerant controller is investigated.The affine parameter dependent uncertain LPV system is built for satellite attitude control with actuator multiplicative faults and the fault tolerant control is designed,which ensures the closed-loop system affine quadratic stability and guaranteed cost for all scheduled parameter changes.The affine quadratic stability reduces the conservativeness of the quadratic stability control algorithm and the control with guaranteed cost makes sure the system has robust performance.Robust gain-scheduled variance fault tolerant control is proposed for satellite attitude control system with actuator multiplicative faults.The controller guarantees both the steady state variance with the upper bounds and regional constraints based on polytope uncertain LPV system.The constraints of the steady state variance make sure the steadystate performance of closed-loop system.The transient performance of the system is ensured by the regional constraints.Moreover,it is essential to research on the design of the controllers considering input constraints of actuators and optimization problems in engineering applications.So robust gain-scheduled variance optimal control with input constraints is further studied.