Robust fault-tolerant tracking control design for spacecraft under control input saturation

Abstract

In this paper, a continuous globally stable tracking control algorithm is proposed for aspacecraft in the<br><br>presence of unknown actuator failure,controlinputsaturation,uncertaintyininertialmatrixand<br><br>externaldisturbances.Thedesignmethodisbasedonvariablestructurecontrolandhasthefollowing<br><br>properties: (1)fastandaccurateresponseinthepresenceofboundeddisturbances;(2)robusttothe<br><br>partial lossofactuatoreffectiveness;(3)explicitconsiderationofcontrolinputsaturation;and(4)robust<br><br>to uncertaintyininertialmatrix.Incontrasttotraditionalfault-tolerantcontrolmethods,theproposed<br><br>controller doesnotrequireknowledgeoftheactuatorfaultsandisimplementedwithoutexplicitfault<br><br>detection andisolationprocesses.Intheproposedcontrollerasingleparameterisadjusteddynamically<br><br>in suchawaythatitispossibletoprovethatbothattitudeandangularvelocityerrorswilltendtozero<br><br>asymptotically.ThestabilityproofisbasedonaLyapunovanalysisandthepropertiesofthesingularity<br><br>free quaternionrepresentationofspacecraftdynamics.Resultsofnumericalsimulationsstatethatthe<br><br>proposed controllerissuccessfulinachievinghighattitudeperformanceinthepresenceofexternal<br><br>disturbances, actuatorfailures,andcontrolinputsaturation.