Abstract
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.
Highlights
Controller design for nonlinear systems to ensure desired performance has been extensively investigated during past decade [1]–[4]
FINITE TIME STATE OBSERVER The main contribution of this section could be concluded as following theorem: Theorem 1: Modal state could be estimated within finite time under state observer (19), and its deduction is listed as follows
In this article, a finite time controller based on finite time state observer is constructed
Summary
Controller design for nonlinear systems to ensure desired performance has been extensively investigated during past decade [1]–[4]. The dual quaternion is used to describe the relative motion between satellites, the dynamic model of dual quaternion is derived and finite time sliding mode is constructed based on the fractional order feedback of dual quaternion. In finite time controller design, the singularity issue, model uncertainty and disturbance torque should be taken into consideration at the same time, but current work most focused on one or two aspects of them, the integral discussion of these aspects is still lacking. A modal state observer to estimate flexible deformation is designed in his work and the model uncertainty of flexible system is taken into consideration Based on this estimation of modal state, the term to offset disturbance brought by flexible appendages is added into attitude tracking controller. The finite-time convergence rate under flexible vibration and unknown disturbance is the main contribution of this article
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