Genetic Algorithm Enhanced Quaternion-Based Fixed-Time Attitude Tracking Control for Rigid Spacecrafts Without Unwinding

Abstract

This article tackles the problem of fixed-time attitude tracking control of rigid spacecrafts subject to unknown inertia and external disturbances. In particular, the approach focuses on developing an anti-unwinding quaternion-based control law that is easily implementable on a real hardware. A nonsingular terminal sliding surface is proposed, from which an adaptive control law is derived that can stabilize both quaternions' equilibria without any prior knowledge of the inertia and disturbances bounds. The theory of Lyapunov is used to demonstrate that the convergence time is bounded regardless of the initial conditions. Furthermore, due to the large number of parameters involved, a genetic algorithm is utilized to tune the controller instead of a plain manual parameter search. The control scheme is validated through a processor-in-the-loop test done with an STM32 ARM-based processor in a Monte-Carlo simulation. The assessment shows promising results both in terms of short settling time and low steady state error. Not only that, but the controller outperforms other attitude stabilization strategies in execution time and FLASH memory usage.