Locomotion analysis and design of a triangular bipyramid rolling mechanism with two modes

Based on 3-RSR parallel mechanism, a triangular bipyramid rolling mechanism with two modes is proposed by using parallelogram mechanism folding technique. The mechanism has folding mode and mobile mode in normal position and singular position respectively. In folding mode, it gains the ability of folding by single degree of freedom, and the ability of folding makes the mechanism decreasing the storage space and acquiring the concealed ability. In mobile mode, the mechanism has three degrees of freedom which makes it rolling by deforming. The structure and the reason of freedom changing are analyzed. A prototype is manufactured to testify the feasibility of deforming method and rolling function.