Abstract: The current gravity compensation methods for the truss hinges of large-scale space deployable mechanism are usually complicated,time consuming and poor accuracy.For this reason,an advanced microgravity assembly method assisted by collaborative robot was proposed to overcome the shortcomings of the existing methods.The architecture and process of microgravity assembly system were proposed.Visual Guidance combined with bounded deviation joint path planning method was used to realize the fast automatic grasping of truss hinge.Then,the kinematics model of the robot based on D-H was constructed,and the Newton-Raphson iterative method was used to realize the on-line compensation of pose error.The equivalent model of gravity compensation was constructed,and the impedance control method based on inner loop position control was used to realize the automatic and stable gravity compensation process.The experimental results showed that the position accuracy of the proposed method met the assembly requirements of the truss hinge component and realized the gravity compensation process in critical damping state,which provided theoretical basis and technical support for high precision assembly and gravity compensation of key components of large space deployable mechanism.

Key words: collaborative robot, space deployable mechanism, microgravity assembly, measurement assisted assembly, critical damping

摘要： 针对大型空间展开机构桁架铰链装配中重力卸载过程复杂、需手工反复调整、装配精度一致性差的难题,提出一种采用协作机器人辅助的桁架铰链微重力装配方法。首先提出协作机器人辅助的微重力装系统架构和工艺流程;然后利用视觉引导结合四元数有界偏差关节路径规划法,实现桁架铰链的快速自动抓取;构建基于D-H法的机器人运动学模型,并利用牛顿—拉夫森迭代法在线补偿位姿误差,提高机器人在桁架铰链装配中的绝对定位精度;最后构建桁架铰链的重力卸载等效模型,并利用基于内环位置控制的机器人阻抗控制方法,实现桁架铰链的自动平稳重力卸载。实验表明,该方法的位姿精度满足桁架铰链装配要求,并可使桁架铰链以临界阻尼形式进行平稳重力卸载,为大型空间展开机构关键组件高精度装配和重力卸载提供理论依据和技术支持。

关键词: 协作机器人, 空间展开机构, 微重力装配, 测量辅助装配, 临界阻尼