Creating an ASM-compliant HMI goes deeper than screen color selection
Simply adopting ASM guidelines for graphics does not create an ASM-compliant HMI. Achieving that level of effectiveness involves a range of factors that address how people interact with the control system.
One of the most common misunderstandings and misapplications of the ASM Guidelines on effective console operator HMI (human-machine interface) design has been an over-emphasis on simply applying a new color palette to all the existing displays for a console position. This is often called a like-for-like HMI migration project. In such projects, there may or may not be improved display style and display layout practices, which would be consistent with the ASM Guidelines as well. One might expect such a like-for-like color palette change project to convert the display in Figure 1(A) to the one in Figure 1(B). Typically, when the DCS HMI is not based on an effectively designed display hierarchy for the console operator position's span-of-control, the result is a flat, wide DCS display system where most, if not all, displays are most accurately characterized as P&ID (piping & instrumentation diagram) detail displays. When given such a DCS display system, console operators will typically use their DCS screens as shown in Figure 2, where each individual console operator picks his or her favorite Level 3 equipment displays, along with the alarm summary display. At best, if the developer has correctly applied the guidelines on use of color and followed good display layout principles, the migrated DCS display system might have ASM-compliant individual Level 3 displays, but the DCS HMI would not be ASM compliant.
What does compliance involve?
Applying the ASM guidelines for HMI design is more than converting color palettes to a grayscale design and eliminating color for everything but alarms. In fact, the guidelines advocate effective use of color, which includes properly specified display backgrounds that are much lighter in hue than is typically in vendor-supplied HMI libraries that claim ASM compliance. However, to have an ASM-compliant HMI, the other guideline categories, in particular display types, display content, and navigation and interaction, need to be implemented as well. This would require, among other implementation details:
- Designing the display hierarchy based on major steps of operation to support operator mental models
- Designing effective Level 2 control and monitoring displays consistent with the display hierarchy so that these Level 2 displays support day-to-day operations
- Identifying the Level 1, 2, 3, and 4 display content based on requirements analyses with subject matter experts so the HMI supports proactive operator situation awareness, day-to-day monitoring and control operations, troubleshooting activities, as well as abnormal situation management
- Designing the previous navigation strategy to a method based on the redesigned hierarchy, using simple, on-screen navigation targets to support operator mental models and quick, error-free use
- Eliminating pop-up displays that cover up operating display content and instead using windows management techniques that assign different display types to specific locations and predefined sizes, and
- Providing simultaneous view of Level 1 overview displays, such as a KPI overview and trending overviews, Level 2 monitoring and control displays, faceplate(s), scratch-pad trending, and alarm summary details (Figure 3), rather than approaching the HMI design as a single screen, single display system (Figure 2).
The guidelines are about more than simply using gray backgrounds and restricting the use of color. Color was only one of 16 categories of guidelines in the original edition. The intent of the ASM HMI guidelines has always been to design an operator HMI framework that supports both proactive operator situation awareness and effective interaction. The second edition (Bullemer & Reising, 2013) shifts the emphasis strongly to the display hierarchy, its role in operator situation awareness, and its role as the basis for operator interaction and navigation. This emphasis led to the removal of the term "display" from the second edition's title to stress the holistic, Effective Console Operator HMI Design. While the ASM guidelines do address the design of individual displays, the overall HMI design framework promoted by the ASM guidelines requires multiple displays at different levels of detail on a console workstation with multiple screens and interaction devices to support the scope of the operator's job.
The recent migration to wide-aspect ratio (WAR) screens is creating opportunities to migrate more directly to an ASM-compliant HMI. In particular, if the migration project abandons the typical single-screen, single-display approach, then the extra pixels in WAR screens provides a place for the HMI to house defined locations for faceplates, trending windows, and Level 4 displays that would otherwise be a pop-up display over the full-screen operating display (Figure 4).
What's new in the second edition of the ASM Guidelines on Effective Operator HMI Design
The Abnormal Situation Management (ASM) Consortium has recently released a second edition of its ASM Guidelines document on effective display design. It has a new title, Effective Console Operator HMI Design, intended to communicate the refocus on console operators and their HMIs. The motivations for the new edition were to incorporate recent ASM Consortium research and to address misunderstandings and challenges to applying the guidelines that have surfaced in recent years.
Released at the end of 2013, and available at CreateSpace.com and Amazon.com, the second edition includes:
- A new preface that outline several common misunderstandings with the first ASM guidelines document
- A new section on HMI design philosophy, covering the overarching philosophical principles that the individual guidelines were originally intended to support
- A new appendix on an ASM-conducted case study on value proposition for adopting the ASM guidelines as a systems approach for the console operator DCS HMI
- A revamped appendix on compliance that emphasizes how to design the console operator's HMI, before concerning oneself with how to design individual displays that would have previously been considered compliant
- A reduction in guideline categories from 16 to 7 with many of the original categories being combined into a new category on lifecycle management. The seven categories are: display types; display content; navigation and interaction; display style and layout; use of color; use of symbols, lines, text, and numbers; and development lifecycle
- A reduction in total number of guidelines from 81 to 64, with 5 guidelines being removed and 12 other guidelines being combined with 9 exiting guidelines
- More than 50% of the guidelines were revised or updated
- 28 new figures, and
- 43 revised figures.