Design of safety mechanism of 3-6 parallel manipulator

A method for designing a safety mechanism of Stewart platform by optimizing the extension ratio of legs is proposed in this paper. The vertex spaces are defined as the set of vertex trajectories. Using the extension ratio of legs as the design parameters, various vertex spaces are developed when the extension ratio has been optimized. The constraint equation is constructed under the consideration of the moving platform's geometric constraints. So the problem of designing a safety mechanism which can meet the geometric constraints of moving platform would be transformed into that of the existence of a solution to the simultaneous equation in the vertex spaces. Finally, Strum theorem is employed to ensure that for any set of vertex trajectories there exist positive-real solutions which can meet the mechanism's actual constraints. Simulations indicate that the Stewart platform, which is designed by the method proposed in this paper, can not only run safely but also have the biggest workspace.