An adaptive time‐varying barrier Lyapunov function‐based attitude tracking control for spacecrafts without angular velocity measurement

Abstract

AbstractIn this paper, based on a novel adaptive time‐varying barrier Lyapunov function (A‐TBLF), we propose an output feedback tracking controller for spacecrafts with adaptive time‐varying state constraints. The adaptive time‐varying barrier is adapted with the real‐time constrained state but not constant or a predefined function. It is guaranteed that the constrained state converges into the predefined domain whenever it starts. Moreover, a barrier update restart scheme is designed in the A‐TBLF method to prevent potential barrier violations. Furthermore, we consider the input explosion of the BLF‐based controller when the state is close to the barrier. A nonlinear margin function is introduced to avoid continuous input saturation, resulting in a smooth and cost‐effective control input. On the other hand, as the accurate angular velocity measurement is assumed to be unavailable, it is proposed an adaptive observer chain with finite‐time estimation to the angular velocity and the lumped disturbance. Therefore, only the attitude angle is used to design the controller and the attitude tracking error can be further eliminated. Simulation results verify the effectiveness of the proposed method, and comparative simulations show the superiorities than other control methods with time‐varying state constraints.