Adaptive Controller For Simultaneous Spacecraft Attitude Tracking And Reaction Wheel Fault Detection

TL;DR

The paper addresses spacecraft attitude control under reaction wheel degradation by introducing a Lyapunov-based adaptive controller that online-estimates RW health via integral concurrent learning (ICL). The method achieves global exponential attitude tracking while adjusting RW health estimates, guaranteed after a finite excitation (FE) condition is satisfied. Stability analysis separates pre- and post-FE regimes, proving bounded parameter error and then exponential convergence of the full state. Simulations with 4–6 reaction wheels demonstrate accurate attitude tracking and online health estimation, highlighting the necessity of the ICL term for learning the RW health despite multiple faults.

Abstract

The attitude control of a spacecraft is integral to achieving mission success. However, failures in actuators such as reaction wheels are detrimental and can often lead to an early end of mission. We propose a Lyapunov-based adaptive controller that can estimate and compensate for reaction wheels degradation simultaneously. The controller incorporates an adaptive update control law with a gradient-based term and an integral concurrent learning term that collects input-output data for online estimation of uncertain parameters. The proposed controller guarantees attitude tracking and its performance is tested through numerical simulations.

Figures (10)

• Figure 1: Coordinate Systems
• Figure 2: Case 1: 4 RW's with ICL term activated.
• Figure 3: Case 1: 4 RW's with ICL term activated.
• Figure 4: Case 2: 4 RW's with no ICL term activated.
• Figure 5: Case 2: 4 RW's with no ICL term activated.