Modeling and control of a bidirectional twisted-string actuation for an upper arm robotic device

In this work a new model for the twisted string actuation (TSA) was proposed and results were compared to the obtained data from various strings. Moreover, a wearable device was designed and fabricated, which was actuated by TSA. Joints were actuated by two antagonistic actuators. To simulate the motion of the elbow of the robot and validate the performance of the controller, a control test bed was designed which could capture the angle of the joint as well as the conflicting error due to antagonistic actuation. A master-slave architecture was adopted to control the joint, while an activity of daily living (ADL), adopted from previous work, was set as the desired trajectory. Test results are shown.