Bidirectional elbow exoskeleton based on twisted-string actuators

In this paper, a bidirectional elbow exoskeleton device based on rotational twisted string actuators is proposed. A novel actuation mechanism incorporating antagonistic motors is proposed and its kinematic model is presented along with its experimental evaluation. Two antagonistic actuation mechanisms provide the motion of the forearm link in both directions thus allowing to position the forearm precisely even in the presence of such disturbances as friction, external forces, and at different positions of the upper arm link. In addition, we propose a method to control the antagonistic exoskeleton based on the actuators kinematics. The developed twisted strings-driven elbow exoskeleton can be effectively used in a variety of haptics, teleoperation, and rehabilitation applications.