空间机械臂末端柔性捕获机构动力学与控制优化

Space manipulator, which plays an important role in on-orbit servicing missions such as docking and transporting, is an essential instrument for space programs. A capture mechanism is mounted on the end of a space manipulator. With this mechanism, target objects can be captured, locked, unlocked and released by the space manipulator. Successful capture of the target is a key step in an on-obit servicing mission. To meet the requirement of kinds of space missions, capture mechanisms are often designed with complex geometric shaped rigid parts and large-deformation flexible cables. Due to the complexity and the large-deformation characteristics, there are still some challenges need to be overcome in efficient and high-precision dynamics modeling and control optimization of a capture mechanism. In this research, flexible multibody dynamics and contact theory are used to develop an efficient model of a capture mechanism, and experiments are designed to validate the proposed model. Based on the simulation model, control optimization will be conducted to get better capture results. The research of this project can lay a foundation for on-orbit servicing and promote the aerospace engineering development of China.

空间机械臂是开展载人航天活动必不可少的工具，在航天器在轨服务过程中起着至关重要的作用。机械臂末端捕获机构安装在空间机械臂的末端，能够实现对合作目标的捕获和锁定，同时能完成对目标的解锁和释放等功能。末端捕获机构对目标载荷的成功抓捕是空间机械臂完成在轨任务的关键。为满足空间机械臂在轨工况全覆盖的设计要求，末端捕获机构通常设计有复杂几何外形的刚性导向机构和大变形绳索组成的软捕获机构，由于机构的复杂性和柔性大变形特性，对末端捕获机构的建模仿真和控制优化在保真度和运行效率上都存在非常大的挑战。本申请项目面向我国航天未来发展重大需求，采用多体动力学和接触力学相关理论对机械臂末端捕获机构进行动力学建模，充分考虑机构中大变形部件和刚性部件与目标载荷的接触特性，并且开展相关实验验证，并根据仿真结果对捕获策略进行控制优化研究，为航天器在轨服务提供一定的理论支撑，并寄望于研究成果能够促进我国航天事业的发展。

柔性捕获机构是空间站核心舱机械臂的关键部件，其捕获动力学分析是典型的多体动力学问题。建立在轨捕获过程中精确高效的动力学模型，对航天器工程和空间科学都有重要的意义。本项目围绕空间机械臂的柔性捕获机构动力学与控制优化问题进行了研究，研究了捕获过程中的软捕获、拖动、锁紧等关键步骤的动力学问题。建立了（1）柔性钢丝绳索与刚性捕获杆对接模型；（2）复杂几何外形的刚性导向机构接触动力学模型；（3）末端执行器与机械臂任务联合仿真动力学模型。在项目进展过程中结合载人航天任务，建立了地面弹簧悬吊试验，并与地面验证任务的测试数据进行了对比，验证了模型的准确性。在仿真模型基础上，结合在轨实际任务规划，开展了千余种不同初始条件下的任务仿真分析工作，结合仿真结果，针对悬停飞行器捕获和舱外爬行两种工况进行了分析，对捕获拖动策略及参数提出了可靠的建议，有力保障了核心舱机械臂的研发和在轨任务设计工作，为机械臂在轨服务提供了重要的理论支撑。该项目其它研究成果属于基础理论研究成果，如接触碰撞建模和机械臂柔性关节特性的辨识等，这些成果为相关工程学科提供了重要的理论支撑。