Adaptive Reduced-Attitude Control for Spacecraft Boresight Alignment With Safety Constraints and Accuracy Requirements

This article investigates the boresight alignment control problem under safety and performance requirements involving pointing-forbidden constraints, attitude angular velocity limitations, and pointing accuracy requirements. Meanwhile, the parameter uncertainty issue is taken into account simultaneously. To address this problem, we propose a modified composite framework integrating the artificial potential field (APF) methodology and the prescribed performance control (PPC) scheme. The APF scheme ensures safety, while the PPC scheme is employed to realize an accuracy-guaranteed control. A switched prescribed performance function is proposed to facilitate the integration, which monitors various constraints and further establishes compatibility between safety and performance concerns by presenting a special PPC freezing mechanism. To further address the parameter uncertainty, we introduce the immersion-and-invariance adaptive control technique to derive an adaptive APF-PPC composite controller, guaranteeing the closed-loop system's asymptotic convergence. Finally, numerical simulations are carried out to validate the effectiveness of the proposed scheme.