Greg: The operator is on a moment-to-moment to basis, making sure the process is safe, reliable and productive. It appears to me that the operator interface developed for the original distributed control systems in the 1970s did not improve much for the next 20 years. If anything, they were going in the wrong direction and getting too colorful and complicated, providing distractions rather than a clear path to the operator task needed. Fortunately, there's been a significant effort starting about 20 years ago and including research by the Center for Operator Performance (COP), an alliance of academia, process manufacturers and automation suppliers. Most important, there is now a practical guide via the ANSI/ISA-101.01-2015 standard, “Human Machine Interfaces for Process Automation Systems.” This standard has considerable synergy with ANSI/ISA-18.2-2016, “Management of Alarm Systems for the Process Industry.” These standards are critical for improving the performance of operators, enabling them to better do the tasks needed for abnormal conditions, operational states and production objectives, increasing process safety, efficiency and capacity. The implications extend well beyond the displays to training and control system configuration besides the operator interface. All automation professionals should take advantage of ISA Standards. ISA members can view a standard for free online by clicking on “View ISA Standards: A Member Benefit,” and logging in with the email and password for their ISA membership account.
Stan: In the June 2016 “Control talk,” we were fortunate to have Nick Sands, DuPont Technology Fellow and ISA Fellow, help us understand important aspects of the ISA Standard on Alarm Management. We build on this need to help the operator by getting input from Bonnie Ramey, DuPont senior process control engineer and expert in human-machine interface (HMI).
Greg: What is a high-level view of what the ISA standard on HMI does?
Bonnie: It might be easier to first understand what the standard doesn’t do. It doesn’t give specifics for colors or shapes or tools. ISA-101 is not about the details of a display. What it does do is provide guidance for the entire HMI lifecycle, from design to operation. This includes general principles, display types, display hierarchy and user interaction. The lifecycle is different than that described in ISA-18.2 for alarm management and ISA-84.01-2004 for safety instrumented systems (SIS). In the HMI lifecycle, building the displays comes after understanding the user requirements, and developing the system standards to meet those requirements. The system standards are the HMI philosophy, style guide and toolkit. The ISA101 committee has started on technical reports that will provide more detailed guidance on developing an HMI philosophy and how to apply the standard to mobile devices.
Stan: What are some of the challenges in applying ISA-101?
Bonnie: I see two challenges. Using the standard to create an HMI philosophy, for example, is just as tricky as actually making the conversion of the graphics in the control room. In our business, we have many different control rooms with many different levels of automation. Gathering the control engineers together to develop an HMI philosophy, and agree to designs for the console, the displays and the HMI system itself takes a lot of time and energy. So of course, the control engineers face that time and discipline challenge. Just as tricky, though, is getting the end user operators to accept the change from what they’ve always had to the something new. Change is hard. Even though the goal is to enable more effective safety, quality, productivity and reliability in the operation of the process, people are always hesitant to accept it simply because they do not want to change anything. At our site, I have trained more than 50 operators on the migration from “free form” to applied HMI design, and I found that 99% of the operators understand and accept the value of the change once they are trained on working examples in their areas. So, it’s all fear and worry about change until the training happens.
Greg: In some COP studies I participated in, we were surprised how, with better HMI design, people with no experience in the process or the automation system could do as well or better than the most experienced operators.
Bonnie: We've seen the same thing here. For example, we have a batch process operation onsite where there's little to no advanced automation. Each step of the process is controlled by automated sequences. Operators have a graphic view of the process, but instead of controlling flow valves or pumps like most chemical process operators, these operators merely use pushbuttons to stop and start various stages of the batch process. As such, their graphics are quite simple, so that area was where we first migrated to graphic displays that used our new design guide. After these same batch operators completed the training on the new displays and features in the HMI, I was able to walk them over to one of the most advanced control-oriented panels on the site, and ask them to identify the highest priority alarm in that process (a process that they had never seen before). Each of these operators was able to navigate to the highest priority alarm, and tell me the corrective actions necessary to mitigate the consequence. Because the console design, system design and display style guides followed our own HMI philosophy in both control rooms, every one of the batch operators could perform the corrective action as well as the most seasoned operators in the advanced process. A well designed HMI should make it that easy for even the newest operator to retrieve help or supporting information for the task at hand. This improved HMI, coupled with operator training, promotes quicker understanding, and simplifies tasks to enable new operators to perform just as well as seasoned operators. This is extremely important considering the aging nature of our workforce and the need for new operators to be effective from the “get-go” with minimal experience in the particular process and control room.
Stan: What are tell-tale signs of a poor HMI design?
Bonnie: Poor HMI design includes a dark room with Christmas-tree graphics showing lots of colors, ornaments, blinking lights and constant noise. We have a control room on-site that is laid out into three different process control centers for three different processes. Process A is in the darkest part of the room. The ceiling light bulbs have been removed so the operators have a better view of the 10 screens with black-background graphics. The graphics have a rainbow of colors, not only to indicate different process lines (like water versus steam, for example), but also the same color that's used to indicate the highest-priority alarm is used throughout these black graphics to indicate that a field device is off or closed. Blinking lights indicate rotating equipment. The alarm is sounding every minute or two, the list of alarms is multiple pages, and the silence button is still employed as the operator keeps one hand on the keyboard throughout the entire shift. Walk 10 feet to the right into Process B: better lighting, gray graphics, no noise, no blinking, no problem. The operator sits at a table a few feet away from the console. The alarm page has a handful alarms, and when new alarms come in, the first button pushed is a navigation button to allow the operator to orient the alarm in the process. If necessary, a button appears on each graphic to allow the operator to distinguish process lines from service lines to help orient them. Acknowledging the alarm only happens after the operator has popped up the additional help. Move 10 feet more to the right and you walk into the “mix.” Process C is struggling to accept the change. Half of the graphics are gray; half are black. Half of the graphics use the alarm colors solely for alarms; half of the graphics still use that primary red to indicate that a pump is off, whether it's supposed to be off or not. Not only is finding alarms tricky in this control room, but finding devices is just as tricky since the old graphics have no logical, left-to-right flow standard. So in the same room, you witness the good, the bad and the ugly. The tell-tale signs of poor HMI design are everywhere. It’s up to the control engineer to make standards part of the design, and implement those standards as a part of the never-ending goal of improving operator excellence, uptime and quality.