Singularity Principle and Distribution of 6-3 Stewart Parallel Manipulator

Based on the kinematics relationship of rigid body, this paper presents a new principle and method of kinematics to analyze the singularity of Stewart parallel manipulator. We study the necessary and sufficient condition that three velocities of three non-collinear points in a body can determine a screw motion. With the condition above, the singularity loci and distribution characteristics of a 6-3 Stewart parallel manipulator for some orientations of the moving platform are studied in three-dimensional space. The singularity loci for the orientations will be a plane and hyperholic paraboloid, or three planes.