Friction compensation and virtual force sensing for robotic hands

This paper presents the latest results in the development of the low-level controller of the robotic hand UBH-IV (University of Bologna Hand, version IV). In particular, the friction effects acting at joint level have been rendered by means of a LuGre-like model and a procedure for the identification of the friction model parameters is described. With the aim of providing an online estimation of the effects due to the interaction of the robotic hand with the environment, a controller able to evaluate the overall external torque acting on the finger joints and to discern between friction and torques generated by the external interaction force without using direct measures of the contact forces is proposed. The identification and control tests are carried over on an experimental setup composed by a single finger phalanx, manufactured with the same material and techniques of the hand itself.