Development and kinematics/dynamics analysis of novel hybrid hand with flexible coupling chain

摘要

Abstract Robot hands are essential components of robots; however, the hand of more complex spatial mechanisms with coupling chains is rarely proposed. This paper proposes a hybrid hand with three underactuated finger plane limbs connected by a flexible closed-loop chain. The degree of freedom (DOF) of the hybrid hand is equal to the number of motors before grasping the object. When the contact force appears between the fingertips and the object, the flexible linkages deform, allowing the hybrid hand to maintain adaptability during contact. As the three fingers make contact with the object, the hybrid hand forms a closed-loop chain with the object, ensuring that the overall DOF remains consistent with the number of motors. Firstly, the hybrid hand’s structural characteristics and DOF are analyzed. Secondly, the kinematics of the hybrid hand are derived, and the relationships among the spring deformation, the kinematics of the fingertip and the input of the hybrid hand are obtained according to the geometric constraints. Thirdly, based on the kinematic results and the principle of virtual work method, the coupling dynamics formula of the hybrid hand is established, and the relationship between the dynamic driving force, dynamic constrained force, spring force and the force acting on the object is solved. Finally, the simulation model of the hybrid hand is constructed in MATLAB to validate the theoretical solution, and the merits of the hybrid hand were confirmed by prototype experiments. This paper aims to support a theoretical foundation for the intelligent control of novel hybrid hands.