High Performance Graphics - Improve Operator Performance
When things go wrong we rely on the operators to quickly resolve issues, they rely on good situation awareness to accomplish this. We can help operators detect and solve problems quicker by applying human factors and best practices in the control room. So many of our customers have spent a lot of time and money on alarm management, a very important aspect of situational awareness. However, they have done this without realizing that alarm problems are usually a symptom of graphic design issues. During alarm projects we often see alarms that are used to provide status information but no action is taken. They should be getting this information visually, however, they have too many screens to navigate through and no real good indication of how close an instrument is to alarming, they simply have to wait until an alarm activates and then they can start to navigate through their screens.
Unfortunately when too many alarms activate, this way of operating breaks down and this failure has a negative impact. The graphics should indicate when a problem is building, then an alarm should activate only if the operator missed it for some reason, as back up. Think of a pilot, navigating through the sky with several instruments that are scanned on a regular basis like speed, altitude, position, course, landmarks, fuel, time, ground, terrain, wind, and radius. He knows when to pull up, change direction and speed remaining vigilant. Pilots do not wait for an alarm to tell them the mountain is too close. Is the job of a pilot any more important than that of an operator?
Before the DCS, operators had a great way to stay in the loop, by scanning instruments that were grouped together based on the way the process interacted, alarms were hard wired and expensive but they were very important and not ignored, real estate was limited but the panel walls were designed for operating objectives and tasks. When the DCS was introduced graphics were designed based on P&ID's and several hundred of them were designed for each operator. They did the best they knew how and the graphics evolved over time but very few companies have spent the time and money to apply human factors to the design. There were no guidelines to follow and color was used to represent many different things, shapes, and lines became cluttered, confusing, and crowded.
Most graphics do a good job of providing data, but it can be overcrowded, very small, lots of color, text, and drawings. You could be trained to know what each value should be, and you could scan the graphic and many others just like it during a 12 hr shift looking for issues, but these types of graphics lead to fatigue, missed events, and force an operator to rely on alarms to alert of a problem. There is no way you can see where these values have been and where they are going without trends. It's almost impossible to predict or prevent issues from happening. When we use these techniques, operator training is mostly focused on understanding the graphics and memorization, when we use human factors operator training is mostly based on understanding the equipment behavior and the process, this allows the operators to be more in tune with quality and safety. The idea is to remove data and provide the operator with information using ergonomic objects.
As DCS vendors evolved, they introduced new tools to design graphics, using 3-D images. The DCS vendors used these capabilities to sell more systems. Unfortunately this made it even worse for the operators. Things starting flashing, popping off the screen, interactive flames representing the flare, but the most important information to the operator is the data. It's very hard to read, you have to look at each value to determine whether things are good or not, you could do this if you were trained on the process but how would you do it effectively if you had 200 graphics to go through? We see these at trade shows all the time. New graphic interface, easily drag and drop objects, easily duplicate screens. The DCS vendors understand that when you design graphics this way, you will have to create hundreds of them so they make it easier for you to copy them and customize them. That is not what we need, we need fewer graphics, designed based on task and objectives, that show the operator when a problem is building and exactly what to focus on to solve the problem. Look at your own screens, identify what the operators really use, you might be shocked to find out that only 10% of the screen is actually being used and it's usually not the most dominant information on the screen.
When we perform an HMI gap analysis for our customers, we almost always find this situation. We ask the operators to simulate a very serious situation. When they point it out on the screen, it's often a where's Waldo scenario. When it should be the exact opposite, abnormal situations should be the most obvious thing on the screen. If the plant was going to start to shut down in 15 seconds, and you had to search through screens like this, your stress level would be very high. Graphics must provide information but when something abnormal is happening, the graphics should make it obvious to the operator, we should not make an already stressful situation worse or impossible.
Use color wisely, limit the number of colors you use, and define each colors purpose within your HMI philosophy. So many people have misunderstood the human factors associated with color and how we see color. We have seen some customers that were proud to show us their high performance graphics, what they actually did was change their backgrounds to grey, but the shade of grey they used was not selected based on the lighting in the control room, they kept all the colors they were using, and did not do anything else. Hey, we have grey backgrounds, we have ASM style graphics. Wrong. The grey background is only about 1% of what high performance graphics include. If you don't incorporate all of the fundamentals and design techniques, the graphics will likely fail and operators will eventually reject them. The use of color, to indicate information, must be consistent throughout all graphics and all control rooms. It's common to move operators from one control room to another. From one console to another. Consistency in the design is a key element to success.
The shade of grey that you use will be determined by the light that is used in the control room. The idea is to light up the control room and reduce glare. Most control rooms are unique and will use different shades of gray. Shades should be tested and discussed. In many cases we change the lighting before we go to grey backgrounds. Never use color, by itself to indicate an important status or change of events. We often see red and green all over a screen. When something changes from red to green, it is not obvious, it blends in, and goes unnoticed. When you want to get an operators attention, think of a stop sign, it uses color, shape, and text. 3 layers of contrast to make sure you see it and know what to do when you see it.
We tend to stay away from color depiction when we draw process lines, instead we use line thickness, shape, or shade to provide additional information. We want to tone down color unless we use it to pop something off the screen to catch the operators attention. This will also improve your training program. It's easier to train an operator to learn the meaning of 7 colors, 3 line shapes, and 2 shades of grey, versus 10 colors on instruments, 10 colors on lines, and 4 colors representing alarms.
If you have ever rationalized alarms and you should have a knowledge base and you should be able to right click the alarm symbol on the graphic and have access to information that could help the operator with the required action, procedures, or check list. This can be very helpful when you have new operators in training or recently out of training. In the future we might not always be able to call on the guy with 30 years of operating experience when we need help.
We often see the cut out view into the vessel but it's not obvious if it's good or bad. We like to see trends inside the vessel with an analog indicator showing what is good and what's bad. It also lets the operator know how it has been behaving, how fast it's been rising, that we are in alarm, and what the priority of the alarm is, right click on the alarm to get cause and corrective action guidance.
One of the worst things we see all the time, green is running and red is stopped. The problem is, when you have a graphic with several pumps the reds and greens do not stand out. It would be ok if you had one pump, but when you have 10 or 20 pumps, they fight for attention so the brain washes them out. If a pump stops and it's a problem it will have a colored alarm indicator next to it. If the pump is supposed to be off it should not be colored, if a pump is supposed to be running we don't need color, color is for operator attention and action not for status. We use analog and trends for status. We use shade to depict if it's running or not, and words next to it, if the pump is running the light is turned on (bright shade), if it's not running, no light (dark shade). If all is well, no action is required, no color is present, and it's still easy to see if it's running or not without reds and greens all over the screen.
We also see fancy P&ID's graphics, where they have become 3-D graphic, no performance indicators, no trends, little color but they still require a lot of mental calculation and several screens to navigate through. When you design graphics correctly, you end up with fewer screens with useful information that guide and assist the operators. It is very important to perform a task analysis during the graphic design phase.
An HMI philosophy document will contain human factors principles that will keep you from making common mistakes. This document is not specific to any DCS. It is centered around human capabilities and limitations. This document defines the methodology for each principle and should be reviewed and understood before the graphic design process starts. This document will keep the HMI designers grounded during the design stage forcing consistency, best practices, and standardization.
You should also have a style guide, a very detailed document that is used during the design stage. It is tied to a specific manufacturers DCS/PLC/or SCADA system. It will contain the object library and descriptions of all the HMI's features and functions of that system. Remember this, the philosophy doc provides the rules that should be followed when building graphics, the style guide is a document that follows the philosophy principles but it's system specific based on the technology of your system.
Everyone has level 3 and level 4's but most are missing Levels 1 and 2. Level 1, is an overview of the operators entire span of control, an image that with a quick scan will let the operator know if a problem is brewing. This is only for situational awareness not control. From there, the operator can go into the level 2 graphic to diagnose process problems.
Nova chemicals redesigned all their graphics incorporating human factors, trends, and large overview displays. With the help of the Abnormal Situation Management Consortium, they analyzed the operators ability to manage abnormal situations using their traditional graphics versus high performance graphics. They looked time to detect problems, success rate and managing the problem, and the time to complete tasks. Based on the results, Nova estimates a savings of $800,000 per year, contributed to improved situational awareness in the control room. We recommend that you start off with a High Performance HMI workshop to educate everyone involved with the process, the key is to get everyone on the same page before you introduce a culture change.