绳系拖拽系统半物理仿真实验装置设计与控制

为有效清除太空垃圾，模拟空间中对废弃卫星的回收过程，采用半物理实验技术对绳系收放装置进行地面试验考核，验证绳系收放控制系统的性能。半物理仿真是一种通过实物或物理模型与数学模型相结合进行仿真的技术，通过地面半物理仿真实验对空间任务进行先验，大大减少了空间实验的成本，可有效指导空间任务的设计与控制。首先，对绳系卫星拖拽过程进行动力学建模，明确了拖拽过程的任务目标，确立了绳系拖拽半物理系统的机械组成。其次，设计了全物理仿真单元为被动加载单元，卫星质量采用等效惯量转台模拟。然后，为模拟目标在绳系拖拽作用下的动力学状态，仿真加载单元由半物理仿真方式设计。最后，针对实际试验过程中存在的张力测量误差扰动，设计了基于模型预测控制的控制策略，为了对拖拽过程的张力和绳长精确控制，实验使用双闭环电机联合控制，通过模型预测控制的方式联合张力位置双电机仿真。结果表明，基于模型预测控制的张力误差精度为5%,从而验证了绳系收放控制系统对拖拽过程的控制有效性。

Design and control of semi-physical simulation device for tether dragging system

To remove space garbage effectively and simulate the recycle process of abandoned satellites in space, we conducted ground test assessments on dragging retractable device by means of semi-physical experimental technology to verify the performance of the dragging system. Semi-physical simulation is a technology that uses physical objects or a combination of physical models and mathematical models for simulation. Ground-based semi-physical simulation experiment can be a priori study for space tasks, which can greatly reduce the cost of space experiments and effectively guide the design and control of space tasks. First of all, the dynamics modeling of the dragging process of tethered satellite was carried out, the mission goal of the dragging process was clarified, and the mechanical composition of the semi-physical dragging system was established. Secondly, the full physical simulation unit was designed as a passive loading unit. The satellite mass was simulated by using an equivalent inertia turntable. Then, the simulation loading unit was designed by a semi-physical simulation method to simulate the dynamic states of the target under the dragging action of the tethering system. Finally, in view of the disturbance of tension measurement error in the actual test process, a control strategy based on model predictive control was designed. To accurately control the tension and tether length of the dragging process, the experiment adopted double closed-loop motor joint control and combined tension position dual motor simulation through model predictive control. Results show that the tension error accuracy of model predictive control was 5%, which verifies the effectiveness of the tether retracting control system on the dragging process.