Modeling and Movement Analysis of a Parallel Torso for a Quadruped Robot

Abstract

The torso is crucial in coordinating the movement of quadruped mammals and its structural characteristics, motion modes, and motion space determine the coordination ability of the quadruped. In this contribution, a variable hinge parallel mechanism is designed to imitate the torso of animals, which is applied as a flexible element of the quadruped robot to connect the fore and hind limbs. The forward and inverse kinematics equations of parallel structures are established and the configuration characteristics are analyzed by the characteristics of inverse kinematics solutions. Taking the spatial motion range as the reference, the relationships among the various structures of the parallel mechanism platform are analyzed in detail, and then we obtained the 3-D motion space of the parallel mechanism under the fixed attitude. Finally, the influence law of each structural parameter on the motion space of the parallel mechanism is determined, which provides a theoretical basis and reference for parameter selection and structure design of similar robots.