Dynamic simulation of tetrahedron-based Tetrobot

Highly redundant parallel manipulators are gaining increased attention due to their capability to meet demands of strength, rigidity, kinematic structure, dexterity, reconfigurability, and fault tolerance. Most previous research has considered the kinematic resolution of highly redundant parallel manipulators, and the dynamic resolution of redundancy has not yet been studied for these systems. This paper presents the dynamic simulation of a highly redundant parallel manipulator called Tetrobot, a class of modular reconfigurable robotic systems. The modular concept is applied to formulate the kinematic and dynamic equations of motion. In this modular approach, kinematic and dynamic solutions are obtained for Tetrobot mechanisms by propagation through the structures. Results show that the pseudoinverse solution which minimizes the norm of acceleration may introduce stability problems, and the null space vector which avoids joint limits is required to ensure stability