Eclipse: an Overactuated Parallel Mechanism for Rapid Machining

This paper describes the design, construction, and experimental results of the Eclipse, a novel 6 d.o.f. parallel mechanism designed for rapid machining. The Eclipse is designed to be capable of performing 5-face machining while retaining the advantages of high stiffness, high accuracy, and compact size characteristic of parallel mechanisms. We describe the kinematic structure of the Eclipse, including computational procedures for the forward and inverse kinematics, as well as results of workspace, stiffness, and singularity analysis. The Eclipse has 8 actuators. The overactuation is necessary in order to eliminate kinematic singularities present in the internal workspace of the mechanism. Experimental results obtained with a prototype capable of machining plastic stock are described. We conclude with a summary of what we believe are some of the critical issues in designing parallel mechanism-based machine tools.