Position and force control of a robotic finger with twisted strings actuation

Actuation and control of robotic hands is one of the difficult problems in mechatronics that still needs to be solved. In this paper we present a kinematic analysis of a robotic finger that is actuated by twisted strings mechanism, which we named Twist Drive. The principle of actuation is briefly described in the paper and a structure of the developed robotic finger is presented. Forward kinematics for a finger with nonlinearly coupled joints is given. The obtained Jacobian is used in position control and in force control on the finger's tip. Experimental results are presented. Force control in two directions is successfully demonstrated.