Theoretical and experimental determination of dynamic friction coefficient for a cable-drum system

Abstract

Cable-drum systems are utilized to convert the rotary motion of a drum into a translational motion of a linear stage connected to the cable. These systems are preferred where low backlash and high stiffness is expected. They are commonly employed in machines like elevators, photocopy machines, printers, plotters etc. For machines having long working ranges, cable-drum systems employing a high resolution encoder offers a practical low cost alternative in position sensing. In most traditional machines and equipments, to get linear position information; potentiometers, linear encoders, laser range finders etc. are commonly used. However, these alternatives are expensive and their installation is not straight forward. Cable-drum systems are not problem free either. The problem coming from using cable-drum system as a linear position sensor grows out of dynamic friction. In this study, the change in the dynamic friction coefficient of the cabledrum system is modeled by using Euler and LuGre friction approaches. In order to see the change of the friction values, the developed model is simulated. To verify of the theoretical results, an experimental set-up is constructed. Both results are presented. It is concluded that for better positioning control change in dynamic friction coefficient during the motion should be accounted for. © Springer Science+Business Media B.V. 2010.