Type Synthesis and Dynamics Performance Evaluation of a Class of 5-DOF Redundantly Actuated Parallel Mechanisms

This paper presents a five degree of freedom (5-DOF) redundantly actuated parallel mechanism (PM) for the parallel machining head of a machine tool. A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method. The evolutional chain and four 6-DOF kinematic chain SPS (S represents spherical joint and P represents prismatic joint) or UPS (U represents universal joint) can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms. That SPS-(2UPR)R (R represents revolute joint) redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool. All formulas of the 4SPS-(2UPR)R mechanism are deduced. The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems (ADAMS) under no-load conditions. The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed. The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.