输入饱和的航天器特征点间相对位姿全状态预设性能固定时间控制

Full-state prescribed performance-based fixed-time relative pose control for feature points of two spacecraft with input saturation

本文研究系统全状态、控制输入及响应时间受约束的航天器特征点间相对位姿跟踪控制问题,提出了一种基于非奇异终端滑模的输入饱和全状态约束固定时间控制器.首先,通过引入预设性能函数,控制器可以保证系统的瞬态和稳态性能达到全状态约束要求.其次,考虑到控制输入饱和约束和时间受限问题,提出了一种固定时间非线性饱和补偿器实时处理执行器的饱和效应,并且保证补偿器的状态在固定时间内收敛.同时,所提出的自适应律可以抑制外部干扰并保证在线估计参数的有界性.最后,基于李亚普诺夫稳定性理论证明了闭环系统的固定时间稳定性.通过航天器近距离逼近操作的仿真算例,验证了该方法的有效性.

The relative pose tracking control problem for feature points of spacecraft with constraints of full states,control inputs and response time is investigated.A full-state constrained saturated fixed-time controller is proposed based on a nonsingular terminal sliding mode.Firstly,the controller can ensure that the transient and steady state performance of the system meets the full-state constraint requirements by introducing prescribed performance function.Secondly,considering the input saturation of the systems and time constraints,a fixed-time nonlinear saturation compensator is proposed to compensate the saturation effect of the actuators,and the compensator state is guaranteed to converge in a fixed time.At the same time,the proposed adaptive law can suppress the external disturbances and ensure the boundedness of the online estimations.Finally,the fixed-time convergence of the closed-loop system states is proved based on the Lyapunov stability theory.The effectiveness of the method is verified by a numerical example of a spacecraft close-range proximity operation.