At the IFAC Conference on Advances in PID Control (IFAC PID’12), Emerson’s Terry Blevins presented PID Advances in Industrial Control. This conference:
…aims at gathering academic and industrial experts in the field in order to present the recent research developments in the design of PID controllers. In addition to provide the current state-of-the-art in the field, the meeting aims at providing a perspective of the future requirements for PID controllers in industry.
The last meeting dedicated to PID control was held in 2000. Technology has changed a great deal in the past dozen years, and this conference presented an opportunity to share how these technologies are having an impact on PID [proportional-integral-derivative] control. It also helps to shape some of the research that leads to innovations in process control.
Here is the abstract of Terry’s paper and presentation:
Major advances that improve control in the process industry have been made over the last ten years in the basic PID technology of modern distributed control systems. This paper addresses the impact that international standards have on control implementation and the tools utilized in industry for monitoring and commissioning PID control. Examples are used to illustrate how new technologies, such as model switching for process identification, have allowed manufacturers to introduce a new level of ease-of-use in tools developed for on-demand and adaptive tuning. This paper discusses PID modifications that improve the speed of recovery from process saturation conditions that are common in industrial applications. Also, details are provided on PID modifications that enable effective control with non-periodic measurement updates by wireless transmitters. Finally, prospective future directions for industrial PID controllers are sketched.
Terry recorded the audio of his presentation and synched his voice back to the presented slides. Here’s the fully narrated version of his presentation:
At the beginning of this 53:13 presentation, Terry highlights some of the control system changes over the past decade—smaller hardware footprints, vastly increased controller CPU power, wireless communications, and distributing I/O channel by channel from the controller. Terry notes that technology innovations are driven by focusing on solving customer issues, closing monitoring technologies developed in other industries, and following and participating in standards efforts such as IEC 61804 and ISA-88 (S88).
He highlights the important role of PID control, both single- and multi-loop, which remains the workhorse of control algorithms used in plants—around 95% of the loops. More advanced controls such as neural networks and model predictive control handle some of the remaining loops. PID has the flexibility to be applied broadly to many classes of control challenges.
I’ll highlight a few of the ideas Terry shares and where you can find them in the presentation. On slide 13 (17:50) he describes how the information in IEC 61804 function blocks including status and mode can be used to monitor the performance of the PID loops. He describes on-demand tuning on slide 16 (20:00). Adaptive tuning is highlighted on slide 17 (20:30), adaptive control on slide 18 (21:00) and recovery from process saturation on slide 19 (21:24).
The largest part of Terry’s presentation is focused on the advancements in PID control for wireless devices used in the control loop. This begins at slide 21 (27:10) and continues through the balance until the question and answer portion begins at 45:00. Terry has been doing a series of posts on this topic on his Modeling and Control blog. I summarized this series in a post, The Story behind Wireless Device Closed PID Loop Control.
If you haven’t heard Terry present and have interest in the direction of PID control, you’ll want to carve out some time to listen to his IFAC presentation.