Study On The Innovation Of Lower-Mobility Serial-parallel Mechanism Based On Movement Function

Serial-parallel mechanism has an optimistic application prospect as a very important branch of parallel mechanism . It not only have the advantages of high rigidity , high precision, but also large motion space. Nowadays, many experts are researching on parallel mechanism, and propose some methods to synthesis parallel mechanism . Actually, some of the mechanism can't applied in practise, because they can't meet the needs of kinematics characteristics or mechanical conditions.Aimed at these problems ,this thesis based on screw theory , study on the motion principle of parallel mechanism and analyse the connections between branch chain force and branch constrained force , Propose a novel serial-parallel mechanism innovation method based on application circumstance.Firstly, study on the mechanism screw motion , propose mechanism synthesis method under the equivalent design principle. Fingd out necessary conditions of parallel mechanism motion.Build up mechanism force analyse model, propose cuting down initiative branch constrained forces method ,and adding virtual constraints and append guide branches methods to optimize mechanism configuration.In this paper ,apply a concrete example 3T-1R serial-parallel mechanism to validate this innovation method ,an choose out the fine mechanism Configuration.