In this paper, the simplified electromagnetic force/torque model and coupled orbit-attitude dynamics modeling in spacecraft electromagnetic docking are investigated, and an improved sliding mode control scheme based on planned trajectory is proposed. In this scenario, the docking two spacecraft are equipped with four energized solenoids with iron cores fixed in the body frame, and small-angle hypothesis is used to derive the simplified electromagnetic force/torque model, based on which the coupled orbit-attitude dynamics equation is established. With trajectory planning of relative orbit and attitude, where the tracking process of coupled orbit-attitude is divided into three successive parts with predefined time using three characteristic time instants, a sliding mode control strategy is proposed to solve the tracking problem. Simulation results illustrate the simplification rationality of electromagnetic force/torque model, and the good tracking performance of coupled orbit-attitude tracking controller at predefined time.

本文研究了航天器电磁对接中的简化电磁力/扭矩模型和耦合轨道-姿态动力学建模，提出了一种改进的基于规划轨迹的滑模控制方案。在该场景中，对接的两艘航天器配备四个铁芯固定在机身框架内的通电螺线管，利用小角度假设推导出简化的电磁力/扭矩模型，在此基础上得到轨道-姿态耦合动力学方程成立。通过相对轨道姿态的轨迹规划，利用三个特征时刻将轨道姿态耦合跟踪过程分为三个连续的部分，并在预定的时间内，提出一种滑模控制策略来解决跟踪问题。