Portable Multi-axis CNC: A 3-CRU Decoupled Parallel Robotic Manipulator

This paper presents a lower mobility parallel manipulator with fully decoupled motions. The proposed parallel manipulator has 3-DOF and can be utilized as a portable multi-axis CNC for parts assembly and light machining tasks that require large workspace and high dexterity. The manipulator consists of a moving platform that is connected to a fixed base by three pairwise orthogonal legs which are comprised of one cylinder, one revolute and one universal joint respectively. The mobility of the manipulator and structure of the inactive joint are analyzed. Kinematics of the manipulator including inverse kinematics, forward kinematics, and velocity equation are deduced. A design optimization is developed to seek the maximal workspace with particle swarm algorithm. This advantage has great potential for machine tools and coordinate measuring machine.