一种远中心并联机构运动学与性能分析

Kinematics and Performance Analysis of a Parallel Manipulator with Remote Center of Motion

由固定移动副驱动的并联机构具有刚度好、精度高等优点,适合应用于外科手术领域。微创穿刺活检等手术要求机器人可驱动手术器械绕远端固定点转动。提出了一种2PURR-PUR远中心并联机构,采用螺旋理论分析了机构的自由度,确定了其运动特性。机构可执行绕远端中心的两个转动运动和一个通过该中心的移动运动。建立机构的位置模型,得到了位置逆解表达式。通过速度分析建立了雅可比矩阵,并得到了机构的奇异位形。机构具有逆解奇异和正解奇异。分析机构的工作空间。基于运动/力传递性能方法,分析机构的性能指标,绘制工作空间内的性能分布图,对机构进行了尺度优化。提出的远中心机构可用于穿刺活检、近距离放射治疗、冷冻手术等单一微小创口的外科手术。

Parallel manipulators actuated by fixed linear actuators have the merits of high stiffness and high accuracy,which are very welcome in surgery field.Surgical operations such as minimally invasive biopsies require the robots have the ability to perform rotations around a fixed remote center.A 2PURR-PUR parallel manipulator with remote center of motion is proposed with its mobility and motion characteristic verified using screw theory.The manipulator can perform two rotational motion around a remote center and a translational motion through that center.Position model of the manipulator is established and inverse position solutions are obtained.Jacobian matrix is derived based on the velocity analysis,which is further used in singularity analysis.It is demonstrated that the parallel manipulator has inverse singularities and forward singularities.Workspace of the manipulator is determined.Using the method of motion/force transmission,the local transmission index of the manipulator over its workspace is sketched.Dimensional optimization is carried out.The proposed parallel manipulator with remote center of motion can be applied in minimally surgical operations with single incision such as invasive biopsies,brachytherapy,and cryotherapy.