Output feedback attitude control of flexible spacecraft under actuator misalignment and input nonlinearities

The attitude tracking control problem of flexible spacecraft subjected to parameter uncertainties, time-dependent external disturbances, actuator input nonlinearity, and input actuator misalignment is investigated in this paper. Explicitly, the proposed strategy addresses the input actuator misalignment and dead-zone issues that increase the controller design difficulties. Initially, a new second-order sliding mode observer (SoSMO) using an extended state approach is developed by adding a correction function to improve observer performance to estimate unwanted system perturbations. Then, a distinct SoSMO-based integral-type sliding mode control (ISMC) structure is designed in a unified manner to guarantee the asymptotic stability of the closed-loop system. Comparative numerical simulations under input actuator misalignment, the dead-zone nonlinearity, external disturbance, and inertia uncertainty are performed to illustrate the effectiveness of the proposed controller.

Automated summary

This paper investigates the attitude tracking control problem of flexible spacecraft under parameter uncertainties, time-dependent external disturbances, actuator input nonlinearity, and input actuator misalignment. The proposed strategy addresses the input actuator misalignment and dead-zone issues, and a new second-order sliding mode observer (SoSMO) using an extended state approach is developed to estimate unwanted system perturbations. A distinct SoSMO-based integral-type sliding mode control (ISMC) structure is designed to ensure the asymptotic stability of the closed-loop system. Comparative numerical simulations are performed to demonstrate the effectiveness of the proposed controller under various uncertainties and disturbances.