Hybrid Mapping Method: from Human to Robotic Hands with Dissimilar Kinematics

Mapping grasps from human to anthropomorphic robotic hands is an open issue in research, because the master hand and the slave hand have dissimilar kinematics. This paper proposes a hybrid mapping method to solve this problem. In the proposed method, fingers in the master and the slave hands are divided into vital and synergic fingers according to their contribution to the grasping task. The tip of the vital finger of the master hand is first mapped to that of the slave hand while ensuring that both are in simultaneous contact with the object to be grasped. Following postural synergy theory, joints of the other synergic fingers of the slave hand are then used to generate an anthropomorphic grasping configuration according to the shape of the object to be grasped. Following this, a human-guided impedance controller is used to reduce the pre-grasping error and realize compliant interaction with the environment. The proposed hybrid mapping method can not only generate the posture of the humanoid envelope but can also carry out impedance-adaptive matching. It was evaluated using simulations and an experiment involving an anthropomorphic robotic slave hand.