IEEE Trans Cybern. 2021 Oct;51(10):5032-5045. doi: 10.1109/TCYB.2020.3024672. Epub 2021 Oct 12.
In this article, a neural-network-based adaptive fixed-time control scheme is proposed for the attitude tracking of uncertain rigid spacecrafts. A novel singularity-free fixed-time switching function is presented with the directly nonsingular property, and by introducing an auxiliary function to complete the switching function in the controller design process, the potential singularity problem caused by the inverse of the error-related matrix could be avoided. Then, an adaptive neural controller is developed to guarantee that the attitude tracking error and angular velocity error can both converge into the neighborhood of the equilibrium within a fixed time. With the proposed control scheme, no piecewise continuous functions are required any more in the controller design to avoid the singularity, and the fixed-time stability of the entire closed-loop system in the reaching phase and sliding phase is analyzed with a rigorous theoretical proof. Comparative simulations are given to show the effectiveness and superiority of the proposed scheme.
本文提出了一种基于神经网络的自适应固定时间控制方案，用于不确定刚体航天器的姿态跟踪。提出了一种新颖的无奇异固定时间切换函数，具有直接非奇异特性，并通过引入辅助函数在控制器设计过程中完成切换函数，避免了由误差相关矩阵的逆引起的潜在奇点问题。然后，开发了一种自适应神经网络控制器，以确保姿态跟踪误差和角速度误差都能在固定时间内收敛到平衡点附近。在所提出的控制方案中，不再需要在控制器设计中使用分段连续函数来避免奇点，并且通过严格的理论证明分析了整个闭环系统在到达阶段和滑动阶段的固定时间稳定性。给出了比较仿真结果，以显示所提出方案的有效性和优越性。
