Adaptive Actuator Fault Compensation and Disturbance Rejection Scheme for Spacecraft
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ISSN:1598-6446 eISSN:2005-4092 http://www.springer.com/12555
Adaptive Actuator Fault Compensation and Disturbance Rejection Scheme for Spacecraft Zhen Li and Xin Chen* Abstract: An adaptive actuator failure compensation scheme is proposed for attitude tracking control of spacecraft with unknown disturbances and uncertain actuator failures. A new feature of this adaptive control scheme is the adaptation of the failure pattern parameter estimates, as well as the failure signal parameter estimates, for direct adaptive actuator failure compensation. Based on an adaptive backstepping control design, the estimates of the disturbance parameters are used to solve the disturbance rejection problem. Without the requirement of additional fault detection mechanism, the switching function is designed to automatically locate and turn off the unknown faulty actuators by observing a control performance index. The asymptotic stability of the system output in the presence of actuator failures is rigidly proved through standard Lyapunov approach, while the other signals of the closed-loop system are guaranteed to be bounded. Simulation results verify the desired adaptive actuator failure compensation performance. Keywords: Actuator failure compensation, adaptive control, disturbance estimation, failure pattern, spacecraft, stability and tracking.
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INTRODUCTION
For the time varying and high nonlinearity of spacecraft, they are inevitably suffered from the disturbance and fault. In [1], for the uncertain inertia parameters and external disturbances, the sliding mode control (SMC) scheme is developed, realizing the stabilization of rigid spacecraft attitude manoeuver. In [2], assisted by a compensator, the stabilization of spacecraft with external disturbances is handled by the designed adaptive controller. In [3], an integrated adaptive approximation that based design that accommodates for both system and Reaction wheel fault uncertainties. The parameter jumps caused by abrupt failures is also analyzed in this paper. Reaction wheels are widely used in a spacecraft as the actuators, which are sensitive devices that are vulnerable to faults during system operations, and the actuator failures are often uncertain in time, value and pattern, which can cause loss of performance and even catastrophic instability leading to serious incidents. To improve safety and reliability of the spacecraft control system, faulttolerant control (FTC) has become increasingly important. An FTC system is capable of automatically compensating for the effects of faults and maintaining the performance of the controlled system, at an acceptable level, in the presence of faults, and has received considerable
attention from the control research community and aeronautical engineering in the past few decades. There are rich results on the application of FTC to spacecraft attitude control system design including multiple-model methods [6], fault detection and isolation (FDI) strategy [7–10], dynamic inversion [11], adaptive designs [12], fuzzy logic systems [13]
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