Workspace of a Hybrid (Parallel-Serial) Robot Manipulator

A hybrid type manipulation system is a combination of closed-chain and open-chain mechanisms or it is a sequence of parallel mechanisms. Parallel manipulators have high stiffness and large load capacity, but suffer from a very limited workspace volume. The hybrid manipulators overcome the limited workspace of the parallel manipulators and at the same time they have high stiffness. The determination of the workspace of the hybrid manipulators is a challenging problem due to the complexity of the solutions of the kinematic problems. Workspace of parallel manipulators has been studied by several researchers (K u m a r [2]; L u h et al. [3]; M e r l e t et al. [4]). However, the determination of the workspace of hybrid manipulation systems has been presented in few papers (e.g. R i c a r d and G o s s e l i n [5]). Different types of workspaces have been used, e.g. Kumar and Waldron (K u m a r and W a l d r o n [1]) introduced the terms reachable and dextrous workspace. Since then, some more terms have been used: workspace with constant orientation, maximal workspace, inclusive maximal workspace, total orientation workspace [3].