Advanced controls for web handling: Ready for production?

Abstract

The science of web handling has numerous control challenges. Longitudinal control is especially challenging because the machine is a distributed, high order, tightly coupled flexible system. Advanced controls were developed in the last few decades, and have been widely applied in several fields, most notably aeronautics, robotics, navigation, and extremely large-scale high-value industrial processes, such as petroleum refining. There have been numerous advanced web handling control strategies papers previously presented at this conference. However, there are few implementations of advanced controls in commercially available web handling equipment.

The Proportional-Integral-Derivative (PID) controller was originally developed in the 1920's. The PID controller dominates web handling controls to this day; virtually all web handling is controlled by variations of the PID algorithm. While an optimized PID controller can perform well, there are superior control algorithms that have higher performance and more flexibility, but they have yet to displace even a small number of PID systems.

While this paper is fundamentally on control topics, this presentation is targeted towards a general web handling audience; a general broad overview will be presented. This paper will provide a brief history of control, emphasizing the role of PID in industry. It will illustrate some of the circumstances that have limited the adoption of advanced web handling control strategies, and propose potential solutions to increase the rate of adoption of advanced web handling controls. In addition, several high value web handling problems that may greatly benefit from these strategies will be discussed.