Experiment on impedance adaptation of under-actuated gripper using tactile array under unknown environment

The experiment on impedance adaptation to achieve stable grasp for an under-actuated gripper grasping different unknown objects with tactile array is conducted. Under-actuated gripper has a wildly application in the field of space robot and industrial robot because of its better shape-adaptation. However it is difficult to achieve stable grasp owning to the uncertain properties of environment. A control strategy of adaptive matching the impedance parameters is proposed to achieve stable grasp. Firstly, the unknown objects are described as linear systems with unknown dynamics, and the parameters of the object are identified with the recursive least-squares (RLS) method through tactile sensor array. Then a desired impedance model is obtained by defining a cost function that includes the contact force, velocity and displacement errors, and the critical impedance parameters are found to minimize it. Finally, an experiment is presented and shows that the proposed impedance model can guarantee the stable grasp for various unknown objects.