A Type Synthesis Method for Parallel Mechanisms Based on SAKCs

摘要

Extending Assur's kinematic chain (AKC) principle of the planar mechanisms to space parallel mechanisms, this paper studies the composition principle based on the space Assur's kinematic chain (SAKC) as well as the type synthesis method based on SAKCs for the parallel mechanisms (PM). First of all, a new expression for the PM composition based on SAKC is proposed, which has clearer physical meaning; Secondly, according to the principle of composition and the formula for calculating the value of the coupling degree k, 53 types of SAKCs with coupling degree k = 0-3 and the basic loop v = 1-5, as well as their analytical expressions, are presented. Also it is found that these SAKCs can express 40 types of SAKC structures which are the basic unit of PMs. Finally, a general and practical method for type design of PM is presented regarding SAKCs as the composition units and meeting the position and orientation characteristics (POC) set as the design goal. One example is illustrated.