Comparison of Active and Passive Dancers for Periodic Tension Disturbance Attenuation in Web Processing Lines

Abstract

This thesis compares the performance of passive and active dancers in a web process line in the presence of periodic tension disturbances. A sinusoidal disturbance, injected into the web line using an eccentric roller, is attenuated using the passive and active dancers. The piston-cylinder for the passive dancer is modeled as a gas spring. The active dancer setup is fitted with a hydraulic actuator and the experiments are conducted for attenuation using PID and IMC controllers. It is seen that the passive dancer mechanism is effective in attenuating web-tension at lower disturbance frequencies. Its attenuation capabilities are limited due to the properties of its passive elements. The properties of a passive dancer can be slightly varied by varying the pressure of the gas in the gas-spring. This limitation is overcome by the active dancer with an actuator. The electro-hydraulic actuator, used in the active dancer has a high bandwidth compared to the electro-mechanical actuator. The IMC controller is found to be satisfactory in attenuating the disturbance up to a disturbance frequency of 28 rad/sec.