航天器有限时间饱和姿态跟踪控制

针对刚体航天器系统,对存在模型不确定性、外界干扰力矩和控制器饱和等条件下的姿态跟踪控制问题进行了研究。首先,考虑未知模型不确定性和外界干扰,且总干扰上界为未知常数,结合快速非奇异终端滑模、快速终端滑模趋近律以及辅助系统构造了基本的鲁棒有限时间饱和控制器,并通过辅助系统直接补偿了控制器饱和;其次,针对系统总干扰具有多项式上界的情形,进一步结合自适应控制算法,对其上界函数中的未知参数进行在线估计,并设计了自适应有限时间饱和控制器。同时,基于Lyapunov稳定性理论证明了所提出控制算法的有限时间收敛特性。最后,通过数值仿真验证所提出控制算法的控制效果,在两种控制器作用下姿态的跟踪精度分别为5×10-5和1×10-5,证明了所提出控制算法的有效性。

Finite-time saturated attitude tracking control for rigid spacecraft

This paper investigates the robust finite-time attitude tracking control problem for rigid spacecraft in the presence of the modeling uncertainty, the external disturbance and actuator saturation. Firstly, based on fast non-singular terminal sliding mode (TSM) surface, fast TSM reaching law, and auxiliary system, an basic robust finite-time saturated controller is designed that takes into account model uncertainties and external disturbances with constant upper bound. A modified auxiliary system is proposed to compensate the actuator saturation effect. Secondly, for the situation that the total disturbance of the system has polynomial upper bound, an adaptive control algorithm is used to online estimate the involved unknown parameters, and an adaptive finite-time saturated controller is designed. Lyapunov stability theory is employed to prove the finite-time stability of the proposed controllers. Simulation results show that the attitude tracking control precisions by the two controllers achieve 5×10-5 and 1×10-5, respectively, verifying the effectiveness of the proposed controllers.