Satellite Sun-Safe Controller Design Based on Super-Twisting Disturbance Observer With Interval Analysis

Abstract

This article investigates a satellite sun-safe controller based on a super-twisting disturbance observer (STDO) with interval analysis. First, a variable gain sliding mode control (SMC) algorithm is proposed to ensure that the satellite can achieve a fixed-axis rotation and sun-pointing attitude. The controller gains are adjusted according to the disturbance estimation value and the interval of the disturbance estimation error. The important feature of the adaptation algorithm is in non overestimating the values of the control gains. To achieve the purpose of non-overestimating, a STDO is constructed to estimate the unknown disturbance. Additionally, the interval of the disturbance estimation error is obtained by interval analysis to update the controller gain in real time. Then, the stability and convergence of the closed-loop system, including the variable gain sliding mode controller and the super-twisting observer, are verified by using the Lyapunov theory. Finally, hardware-in-the-loop (HIL) experimental results demonstrate that the proposed method not only performs better in terms of convergence and accuracy than the state-of-the-art sun-safe controller design method but also achieves more negligible chattering in the presence of disturbance torque compared to the fixed gain SMC method.