Structural synthesis of a class of two-loop generalized parallel mechanisms

The conventional parallel mechanism (CPM) is characterized by connecting serial kinematic limbs or chains to the moving platform or linkage. The mobility and motion pattern of the CPM may be further constrained by adding a coupling sub-chain to serial kinematic chains. That will result in a new class of mechanisms called generalized parallel mechanisms or GPMs for short. While the systematic mobility analysis and structural synthesis of GPMs are more challenging and have rarely been studied, the application of the coupling sub-chain possesses the potential for enhanced functionality and performance. This paper proposes a novel approach for synthesizing two-loop mechanisms with coupling sub-chains that form the basic building blocks for GPMs. The screw theory based constraint synthesis method is advocated. Examples are enumerated to demonstrate the feasibility of the proposed approach.