Kinematic Analysis and Gait Planning of a Novel Rigid–Flexible Coupling Rolling Mechanism

A novel rigid–flexible coupling rolling mechanism is proposed, which is composed of three planar 3R branched chains, two triangular flexible joints and three flexible cables. The degrees of freedom and kinematics of the rigid–flexible coupling rolling mechanism are analyzed, and the relationship between the input parameters and the rolling velocity is obtained. The projection of the CoM (center of mass) workspace of the mechanism is solved by the equivalent planar mechanism method. Two kinds of motion modes are designed for the mechanism: one is the star gait rolling mode, and the other is the deformable triangular prism rolling mode. In the star gait rolling mode, a rolling gait with minimum impact is designed. The motion mode of the deformable triangular prism includes creeping motion and rolling motion, which combines the advantages of the two kinds of motions to improve both motion efficiency and motion accuracy. Finally, a prototype is developed, and the rolling motion of the mechanism is verified.