Development of an haptic interface based on twisted string actuators

In this paper, a cable-driven haptic interface able to move in the six-dimensional space, suitable for applications in various robotic scenarios is presented. The device takes advantage of four force-controlled twisted string actuators to generate a linear force along the three Cartesian space dimensions while providing a considerable force-weight ratio and low inertia. The system consists of a frame fixed to the ground, where the twisted string actuation modules are arranged, and by a mechanical interface devoted to the physical connection of the actuators with the forearm of the human operator. This mechanical interface allows to secure the forearm of the user while leaving to her/him the freedom to use the hand to accomplish other tasks, such as teleoperating a robotic gripper. The four twisted string actuators allow to control the three linear DoF of the haptic interface, allowing both Cartesian position and a force regulation. Both the design, the simulation and the preliminary implementation of the haptic interface are presented in this work.