Twisted String Actuation Systems: A Study of the Mathematical Model and a Comparison of Twisted Strings

This paper presents an improved mathematical model of a twisted string transmission system. The proposed mathematical model has been validated experimentally and provided a better match with the practical data in comparison with the conventional model. Translational transmission systems based on twisted strings coupled with electric motors can compose light-weight, compact, and mechanically simple actuators that can be used in various robotic applications. An extensive experimental study on the performance of different types of strings during twisting is presented. The drawbacks and advantages of each type of strings, along with some of their properties, are discussed.