Integration of Prescribed Performance With Control Barrier Functions for Attitude Control and Allocation With Reaction Wheels

For an attitude control system, the control law determines the required torque command to achieve desired orientation, while control allocation translates these actions into specific commands for the actuators. This article presents a novel method for managing both complex state and physical constraints at the control allocation level. Such a method is distinctly different from traditional designs at the control law directly, therefore enhancing practicality and flexibility. Specifically, a physics-based control barrier function (CBF) is constructed by analyzing prescribed performance constraints and attitude motion, addressing the shortcomings of traditional methods related to numerical singularities and excessive control torques. The CBF is seamlessly integrated into the quadratic programming problem of control allocation, enabling the allocator to filter commands from control laws to ensure compliance with constraints from both prescribed performance requirements and the reaction wheel (RW) speed. In addition, a modified PD+ controller tailored for RW-actuated systems is introduced, incorporating the speed of RWs to achieve high-precision attitude tracking. The theoretical foundations of the proposed methods are proven, and their effectiveness and superiority are demonstrated through extensive simulations.