Assembly Mode Changing in Parallel Mechanisms

Parallel mechanisms usually have several direct kinematic solutions that are attributed to different assembly modes (AMs) or postures. The present investigation deals with AM changing, and shows that beside the known cusp points, it is possible to change AM by moving on a path like a ramp, while encircling an alpha-curve in the joint space. For micromechanisms, where clearances at the mechanism joints are relatively large, AM changing may also occur when approaching a direct kinematic singularity.