Workspace analysis and dimensional synthesis for a PKM with multi-motion modes

This paper examines the kinematic performance of a multi-motion-mode parallel kinematic machine (PKM) and proposes a dimensional synthesis method based on an overall kinematic performance index to meet the flexible production demands in aerospace manufacturing. Firstly, mobility analysis of the PKM in different motion modes is conducted utilizing the screw theory, followed which a unified inverse kinematic model is formulated. Then, considering corresponding constraints, the reachable workspace of the PKM is analyzed. Meanwhile, a reachable workspace volume index is defined, based on which parametric analysis is conducted. Finally, a coordinate-independent overall kinematic index considering motion modes is proposed, based on which dimensional synthesis is conducted. Results demonstrate that dimensional parameters have an important influence on the PKM’s reachable workspace and kinematic performance. This study offers a theoretical foundation for assessing performance, designing parameters, and developing prototypes of multi-mode parallel robots.