A Novel Measurement Model of Twisted String Actuating System

Twisted string were used in constructions, military, and other areas applications. Such twisted string actuation impression allows the install of simple mechanism, intrinsic compliance, low weight, cheap, and high transmission ration. Nowadays, twisted string actuators (TSA) have been confirmed to be an efficient illumination for generating linear motion with huge tensile force. Thus, the main goal of this proposal is concentrated on deign of mobile platform based on Twisted String Actuator (TSA) to meet low cost and simple structure demand request. A string pair is linked in parallel and attached to the servomotor, and the other end to the payload to be actuated. The rotation intruded to the strings by the servomotor diminishes their length, producing a linear motion at the payload side. Moreover, a thin film potentiometer is equipped to measure the actuation elongation. However, in case of the presence of several unmodeled effects such as the string friction and radius variation due to elasticity, specific consideration has been given in confirming the robustness of the control system against measurement noise and parameter uncertainties. Hence, the new measurement methodology which takes into account fiber tension compensation terms is proposed for modify the positioning tasks. Experimental results confirm that such design is reliable and possesses low implementation cost.