四自由度对称并联机器人结构综合方法

利用螺旋理论,分析了少自由度并联机构中支链运动螺旋系与动平台约束螺旋系的关系,列举了五阶运动螺旋系的支链类型,在此基础上提出了一种四自由度对称并联机器人结构综合的方法,并利用该方法针对动平台3转动1移动的运动特征要求,进行了结构综合,得到多种具有对称结构的四自由度并联机器人机构类型.结果表明:少自由度并联机构的运动与约束通过螺旋数学模型来表达简单直观,便于机构的型综合;同时该方法针对给定动平台的运动特征,可以方便快捷地进行对称结构的型综合,有利于少自由度并联机器人机构的结构创新,为少自由度并联机构的优化设计奠定了基础.

Structural synthesis method for 4-degrees-of-freedom symmetrical parallel manipulators

Based on screw theory, the relationship between motion screw system of limbs and constraint screw system of moving platform were analyzed. All possible 5-order motion screw systems of limbs’ structures were enumerated, and then a systematic method was presented for structural synthesis of 4-DOF (4-degrees-of-freedom) parallel manipulators with symmetrical structure. According to their motionproperty, using this method, a serial of manipulators with 3-translation and 1-rotation mobility that had different structures were gotten. Results show that method has simple expression form for structural synthesis of lower mobility parallel manipulators relying on the relationship between motion and constraints that both have the screw models for easily analyzing. Results also show that the method can be easily applied for structural synthesis, and can be efficiently and fleetly used for structural synthesis of symmetrical mechanisms based on the given motion property of moving platform. It establishes the foundation for optimizing design for lower mobility parallel manipulators.