Designing the perfect HMI (human-machine interface) for pipeline SCADA is an ongoing art, utilizing advances in technology as well as our understanding of human psyche and cognitive processing. The ideal design principles also move with what the industry sets as the primary operational goals. As the oil and gas industry zeros in on reducing pipeline accidents, HMI design focuses more and more on leak prevention and detection.
Since controllers spend hours each day watching data from dozens of pipelines stream into their centralized control room, it is critical that the HMI allows the controller to maintain situation awareness at all times. Poorly designed HMIs can interfere with a controller’s ability to quickly detect and resolve abnormal situations, which is why the American Petroleum Institute (API) is working to update guidelines on best practices for HMI display design. These changes are critical to reducing upsets, improving process efficiency and increasing productivity.
HMI displays have been greatly improved by advances in visualization design and cognitive engineering methods. Functional overview displays are becoming more popular, as operators realize the need for controllers to have improved situation awareness while monitoring overview displays.
Functional overview displays differ from schematic displays because they offer less detail, but instead use design shapes (or coding) that are designed to support situation awareness of process conditions. Coding typically includes color, shape and supporting text. Information in the new display shapes are presented so the controller can qualitatively perceive normal operating limits, alarm limits, how close the process is to its limits, and how quickly the process is moving towards or away from the limits. Schematic displays can be cognitively demanding, because controllers must judge whether an abnormal condition is occurring, whereas with a functional overview display, visual cues draw controller attention to abnormal process deviations and alarms.
Maximizing Control Room Efficiency
Often, while controllers monitor HMI displays, they are simultaneously doing other control room tasks. Their full attention may not always be on the HMI display in front of them, and when displays are crowded with details, it can be especially difficult to weed out what’s really important. HMI displays need to clearly illustrate abnormal process deviation in a streamlined way, so that controllers can have strong situation awareness of the process conditions they are observing. Without strong situation awareness, controllers spend too much time looking for abnormal conditions, which takes away from their ability to supervise and efficiently operate the pipeline.
The ASM® Consortium funded experiments to test whether functional overview displays really are more effective than schematic overview displays. The study proved that new display shapes supported qualitative perception of process conditions, which resulted in improved controller situation awareness while monitoring HMI displays.
The design of the HMI plays a critical role in a controllers’ ability to effectively operate the pipeline—particularly when detecting and resolving an abnormal situation. It is clear from the results of the experiment that the changes to HMI display are making it easier for controllers to recognize abnormal situations and maintain an increased level of situation awareness, even while simultaneously completing other tasks. This allows controllers to effectively operate the pipeline while reducing accidents—outcomes which should be every operator’s goal.
By: Kelly Doran