The typical six-axis industrial robot arm has three types of robot singularity: wrist singularities, elbow singularities, and shoulder singularities. A wrist singularity occurs when the axes of joints 4 and 6 are coincident. An elbow singularity occurs when the wrist center lies in the same plane as the axes of joints 2 and 3. Finally, a shoulder singularity occurs when the wrist center lies in the plane passing through the axis of joint 1 and parallel to or passing through the axis of joint 2.