Shujian Sun

This paper 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 PrescribedPerformance Control (PPC) scheme. The APF scheme ensures safety, while the PPC scheme is employed to realize an accuracyguaranteed control. A Switched Prescribed-Performance Function (SPPF) 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 (I&I) 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.

This paper focuses on the spacecraft attitude control problem with intermittent actuator activation, considering the parameter uncertainty and external disturbance issue simultaneously. To address this problem, we propose a Composite Event-Trigger Mechanism (CETM), which consists of two state-dependent triggers governing the activation and deactivation of actuators. Subsequently, by introducing the cascaded decomposition of the Backstepping control philosophy, the designed CETM trigger mechanism is applied to the decomposed dynamical subsystem, providing a layered intermittent stabilization strategy called the Composite Event-Triggered Intermittent Control (CETIC). Moreover, the proposed CETIC framework is further extended to address exogenous perturbations by introducing the extended-state observer technique, and a Disturbance Observer-based Composite Event-Triggered Intermittent Controller (DO-CETIC) is then developed. Further, by analyzing the boundedness of the Lyapunov certificate on each inter-event time interval, a uniformly, strictly decreasing upper bound of the lumped system is then characterized, completing the proof of the system's ultimate boundedness. Finally, numerical simulation results are illustrated to demonstrate the effectiveness of the proposed control scheme.

This paper investigates the boresight alignment control problem under safety constraints and performance requirements, involving pointing-forbidden constraint, attitude angular velocity limitation, and pointing accuracy requirement. 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 (SPPF) is proposed to facilitate the integration, which monitors various constraints and further establishes compatibility between safety and performance concerns by leveraging a special PPC freezing mechanism. To further address the parameter uncertainty, we introduce the Immersion-and-Invariance (I\&I) adaptive control technique to derive an adaptive APF-PPC composite controller, further guaranteeing the closed-loop system's asymptotic convergence. Finally, numerical simulations are carried out to validate the effectiveness of the proposed scheme.

This paper focuses on the spacecraft attitude control problem with intermittent actuator activation, taking into account the attitude rotation rate limitation and input saturation issue simultaneously. To address this problem, we first propose a composite event-trigger mechanism, which composed of two state-dependent trigger that governing the activation and deactivation of actuators. Subsequently, by introducing the cascaded decomposition of Backstepping control philosophy, the designed trigger mechanism is then applied to the decomposed dynamical subsystem, providing a layered intermittent stabilization strategy. Further, the basic intermittent attitude controller is extended to a "constrained version" by introducing a strictly bounded virtual control law and an input saturation compensation auxiliary system. By analyzing the local boundedness of the system on each inter-event time interval, a uniformly, strictly decreasing upper boundary of the lumped system is further characterized, thereby completing the proof of the system's uniformly ultimately boundedness (UUB). Finally, numerical simulation results are illustrated to demonstrate the effectiveness of the proposed scheme.