Suboptimal attitude control of unknown flexible space debris

Abstract

This paper introduces a suboptimal controller with guaranteed global convergence for attitude control of space debris with unknown mass and flexibility properties. The proposed output-feedback control scheme can be implemented in real-time, does not need velocity measurements, and even under actuator faults and external disturbances converges to the vicinity of an energy-optimal solution. The controller essentially modifies the active disturbance rejection control scheme with variable state-dependent gains to minimize the energy cost function based on the solution of the Riccati equation. It is especially applicable to efficient detumbling of decommissioned or dysfunctional spacecraft with flexible solar panels, antennas, and booms, using a Deorbiter CubeSat. Simulations are carried out to demonstrate the effectiveness of the proposed scheme versus proportional-derivative controllers with an extended state observer, which need a system model for assigning their gains, as well as conventional active disturbance rejection controllers.