Connecting Assembly Modes for Workspace Enlargement

This paper introduces an approach for increasing the useable workspace by realizing a continuous motion between different assembly modes. The workspace envelope is defined as the set of all elements of all workspaces of the different assembly modes. For a planar PRRRP parallel manipulator with 2 DOF this definition is explained. The crossover poses from one assembly mode to another are given by different singular configurations. Using the planar manipulator and its workspace and singularities, different methods are developed how a continuous motion from one assembly mode to another, i.e. passing the singularities, can be realized. Finally a prototype of the PRRRP parallel manipulator is presented on which the described approach could be implemented. First experiments prove the principle.