Fuzzy Control Of Spacecraft Attitude Based On T-S Model

The spacecraft attitude control system is one of the most important subsystems ofthe spacecraft system, and is the core part of the spacecraft. The autonomousattitude control of spacecraft has very wide applications. Currently, the highdemand on the spacecraft attitude control system is particularly important in termsof spacecraft precision, long life, and high ability. The spacecraft control algorithmdesign has a direct impact on the attitude control performance. Aim at a variety ofcontrol problems of spacecraft attitude maneuver process, this thesis focuses on theattitude model establishment, control law design and control parameters selection.Accordingly, it put forward a set of feasible control law design method in order toresolve the rigid spacecraft attitude fuzzy control problem. The following works arefinished in this thesis.Firstly, spacecraft attitude control system not only satisfies a single performance,but also considers the needs of multiple control performance targets. However, thegeneral attitude control system mostly concentrates on the control system stability,and a number of performance targets are not considered simultaneously. For thisphenomenon, this thesis studies the spacecraft attitude control of multi-objectivesynthesis problems based on Linear Matrix Inequalities, for example systemstability, disturbance rejection, input constraint and decay rate. In order to achieve abetter approximation of spacecraft attitude nonlinearity, the T-S fuzzy model isconstructed. The single objective LMI is unified into an LMIs, and themulti-objective controller is designed into LMI convex optimization problem. Bythree cases contrast, the control system has a good transition process anddisturbance rejection capability.Secondly, for spacecraft attitude control, all state information is not all exactlyobtained by sensor, which makes the control performance descend. Meanwhile, thehigh-precision sensors are also very high expensive. Taking into account themoment of inertia of the spacecraft, an output feedback control method is proposedbased on the spacecraft attitude T-S uncertain fuzzy model. The quadratic costfunction with the spacecraft attitude control inputs and attitudes is as a fuzzyclosed-loop system performance, smaller upper bound is obtained. The closed-loopfuzzy system is robustly asymptotically stable for all parameter uncertainties, whichensures that the spacecraft attitude has a good transition process, but also to meetthe constraints of the spacecraft actuator output torque.In addition, the significant issue of the spacecraft control system design is safetyand reliability. So the fault-tolerant control mechanism of the spacecraft control system must be established in order to achieve the autonomous control ofspacecraft and to help it complete the scheduled mission successfully in a longerperiod of time and complex space environment. To solve this problem, this thesisstudies the design of the fault-tolerant controller under the conditions of spacecraftcontrol sensor fault and actuator fault based on the T-S fuzzy system. It proposes arobust fault estimation and compensation method for sensor failure in the presenceof disturbance. The augmented described system is constructed through the sensorfault as auxiliary state vector. By the proposed fault compensation method, thecorrect measurement information can be obtained and the system will still be able tooperate normally. And satisfied fault-tolerant controller is obtained under theconditions of an actuator fault satisfying control input constraints, the pole disk.When the actuator is fault seriously, the proposed control law is still better toachieve control of the spacecraft attitude to meet the requirements ofmulti-objective performances. Simulation tests verify that the proposed designmethod is feasiable and effective.At last, this thesis studies the fuzzy robust control system based on the T-S modelwith time-delay. Aim at delay in the control system, this thesis proposes a designmethod for state feedback controller based on T-S model. By parallel distributedcompensation strategy and applying Lyapunov function, a sufficient condition fordelay-dependent is obtained based on T-S model and converted to be expressed inthe form of LMIs. The maximum allowable time-delay in this thesis is lessconservative. This strategy is applied in spacecraft attitude control system and thefuzzy state feedback controller has good closed loop stability.