新型SSRMS构型可重构空间机械臂的运动学奇异性分析

Kinematic Singularity Analysis of a Novel SSRMS-type Reconfigurable Space Manipulator

大型化、多样化和高精度化的在轨建造任务日趋增多,对舱外作业空间机械臂的能力提出了新的需求。传统SSRMS构型空间机械臂虽然被广泛地应用于在轨服务,但是其具有针对于特定任务设计的结构特点,限制了单个机械臂执行不同种类任务的能力,难以适应未来在轨任务复杂化发展的应用需求。为此,提出了一种新型的具有两个被动式伸缩臂杆的SSRMS构型可重构空间机械臂,并对其运动学奇异性进行了深入分析。首先,通过介绍新型机械臂的结构特点及可重构原理,总结了此类机械臂的工作性能优点,证明了其具备在未来的复杂在轨任务中扮演重要角色的潜力。然后,建立了新型机械臂分别在自由空间操作和重构操作时的微分运动学方程,通过对微分逆运动学方程的分析确定出了包含运动学奇异条件的雅可比矩阵。接着,提出了一种简单可靠的运动学奇异性分析方法,在雅可比矩阵中求解得到了新型机械臂的全部运动学奇异条件。最后,以新型机械臂为例进行了实验验证,结果表明:奇异条件不仅能够正确的确定出新型机械臂的奇异位形,而且在机械臂执行操作任务时可作为先验条件指导机械臂的避奇异运动控制,为操作任务的可靠执行提供了有力保障。

With the increase of large-scale,diversified,and high-precision on-orbit construction tasks,new demands on the capabilities are put forward for extra-vehicular space manipulators.Although the traditional SSRMS-type space manipulator is widely used in on-orbit services,it has task-specific structural characteristics that limit the ability of an individual manipulator to perform different types of tasks.Thus,the traditional manipulator has difficulty meeting the demands of the complicated development of future on-orbit tasks.To this end,a novel SSRMS-type reconfigurable space manipulator with two passive telescopic links is proposed,and its kinematic singularities are analyzed in depth.First,the advantages of the work performance for the new manipulator are summarized by introducing its structural characteristics and reconfigurable principle.They proved that the new manipulator has the potential to play a vital role in future on-orbit tasks.Then the differential kinematics equations of the new manipulator in free space operation and reconstruction operation are established,respectively,and the Jacobian matrix that contains kinematics singular conditions is obtained by analyzing the differential inverse kinematics equations.Next,a simple and reliable kinematic singularity analysis method is proposed,and all kinematic singularity conditions of the new manipulator are obtained by analyzing the Jacobian matrix.Finally,the new manipulator is taken as an example,verification experiments are carried out.The results show that the singularity conditions can not only correctly determine the singularity configuration but also serve as an a priori condition to guide the singularity avoidance motion control when the manipulator performs the operation task,providing a powerful guarantee for the reliable implementation of the operation task.