Finite-Time Control Algorithm Based on Modal State Observer for Flexible Satellite Attitude Tracking

An attitude controller with finite time convergence rate for satellite attitude tracking issue considering the flexible dynamic based on a finite time modal state observer is proposed in this article. The deformation of flexible appendages is taken into consideration and a finite-time state observer with auxiliary state to offset the initial error is proposed to get the flexible vibration estimation. The modal state and its derivative could be estimated by a full dimensional feedback observer. A finite time sliding mode based on the fraction order feedback of MRP is constructed and the finite time controller is proposed. The modal estimation is implied in controller design hence the counteraction of flexible system could be offset. System global finite-time stability is proved by Lyapunov method and the superiority is demonstrated by simulation results.