Experiments of fine manipulation tasks with dexterous robotic hands

In this paper, the experimental evaluation of fine manipulation tasks executed by the DEXMART Hand is presented. The robotic hand is characterized by a compliant actuation system and soft contact interfaces. The manipulation is controlled by feedback information acquired by optoelectronic tactile sensors integrated into the fingertips of the robotic hand. An impedance-like control scheme has been implemented to allow the simultaneous control of the finger positions and contact forces, thus preventing position drift caused by asymmetric force measurement between different sensors. This approach allows also to decouple the control of the normal force applied to the object to prevent slip from the control of the tangential forces applied to the object surface to perform manipulation. Moreover, the evaluation of manipulation tasks of soft objects with variable weight is presented to show the ability of the system to hold the object by applying the minimum required normal force to prevent slip. The performance evaluation has been carried out by considering fine manipulation tasks executed with a simplified setup composed by two opposed fingers, and manipulation tasks of various objects involving the whole DEXMART Hand are presented, as a demonstration of the device capabilities.