A Digital Twin-based condition monitoring system to detect and resolve web slip at traction rollers in a web processing machine

Slippage of web material over rollers is an undesirable phenomenon in web processing applications, causing damage to the web material. This leads to compromised quality and increased waste. While web slippage is commonly observed at high web speeds due to air entrapment on freely rotating rollers, it also occurs at lower web speeds at the traction rollers, which are designed to drive the web through the machine. Installing web speed sensors to detect such web slippage on multiple traction rollers in large-scale web processing machines is expensive. This work presents a novel Digital Twin methodology for online condition monitoring and fault detection to identify web slip at the traction rollers. The Digital Twin uses the contact forces between the web and the traction roller to detect web slippage, greatly reducing the need for web speed sensors and thereby cutting costs and time. Additionally, in response to detected web slip, the newly proposed Digital Twin further acts to resolve the slip. Experimental results demonstrate the effectiveness of the Digital Twin in detecting and resolving web slippage on three different web materials. • Web slip is shown to occur in web processing machines under low web tension and during accumulator operation. • Contact forces are cost-effectively measured from the servo motors to detect web slip. • A digital twin reflecting changing system conditions enables accurate online web slip detection. • The friction coefficient identified on one roller can be used to detect web slip on other identical rollers under different operating conditions. • Detecting web slip online enables immediate control feedback to resolve it.