基于球面五杆机构的变胞并联机构构型综合

Type Synthesis of Metamorphic Parallel Mechanism with Spherical Five Bar Linkage

提出一类基于球面五杆机构的变胞并联机构。基于具有解耦特性的球面五杆机构,应用螺旋理论综合出一类具有变胞特性的可重构混联支链,该混联支链由一个球面五杆机构和一个四自由度串联支链混联而成,应用三条相同的所述可重构混联支链构型出一类变胞并联机构。不同于现有利用约束奇异和支链奇异综合可重构并联机构的方法,提出利用球面五杆机构的解耦特性和关节锁死的方法来实现并联机构的可重构,因此该类变胞并联机构可有效避免重构过程中的约束奇异以及支链奇异。该类变胞并联机构可在一个广泛的范围内变换其工作模式和自由度,且伺服电动机均可安装在机构的固定平台。提到的方法可应用于其他基于解耦闭链的变胞并联机构构型综合。

A new family of metamorphic parallel mechanism with spherical five bar linkage is presented. Based on the spherical five bar linkage with decoupling performance, reconfigurable hybrid limbs with metamorphic performance are obtained by using screw theory. Reconfigurable hybrid limbs are obtained by integrating the spherical five bar linkage with four degree of freedom serial limbs. A class of metamorphic parallel mechanisms is constructed with three identical hybrid limbs connecting the moving platform and the fixed base. Different from the existing methods by using constraint singular configuration or self-motion of sub-chain of a leg to synthesis reconfigurable parallel mechanisms, an approach to the type synthesis of metamorphic parallel mechanism with lockable joints by using five bar linkage with decoupling performance is presented. It is found that these metamorphic parallel mechanisms do not encounter constraint singular configurations and self-motion of sub-chain of a leg during reconfiguration. It is also found that these metamorphic parallel mechanisms have the ability to change working mode and mobility in a wide range, and all servomotors can be arranged on the base. The approach can also be used for synthesizing other classes of metamorphic parallel mechanism with decoupling closed loop linkage.