Experiment on Impedance Adaptation for an Under-Actuated Gripper Grasping an Unknown Object with Tactile Sensing

This paper presents an experiment on impedance adaptation for an under-actuated gripper grasping an unknown object. Under-actuated gripper has broad applications in the field of industrial robotics and on-orbit services because of its better self-adaption. However, subject to uncertain characteristics of the object, it is difficult for an under-actuated gripper to achieve stable grasp. To address this problem, this paper develops impedance adaptation for an under-actuated gripper manipulation with the tactile sensing. A cost function that measures the contact force, velocity and positioning errors of the contact point is defined and the critical impedance parameters are determined that minimize it; this adaptation is feasible for an under-actuated gripper to guarantee a stable grasp without requiring information on the object dynamics. Finally, an experimental setup is established to verify the validity of the proposed method. The experimental results demonstrate that the under-actuated gripper can stably grasp an unknown object.