"When computers were first put into use in
industrial processes for the purpose of HMI they had only the most basic
graphical capabilities. Eventually the computing systems gained more and more
graphical capability and the HMI applications also
began to leverage these improvements with little thought of whether that was
the right choice to make. It has become commonplace for the HMI applications to
become a show piece that emulates the process in a very visual manner and often
that visual presentation is used to justify the automation investment to key stakeholders.
However, these very elaborate visual approaches often impair the operator’s
ability to ascertain the current situation and ultimately make key decisions to
maximize the business value of the application.
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| Figure 10 - Example of Poor Color Usage |
In Figure 10 the process is displayed with
three dimensional pipes and flanges that offer the operator no real
information, gauges with artificial glare applied, the color red has several
meanings, and a variety of other bad practices. In the version of that same
graphic shown in Figure 11, there is a much better use of color. Often people
will comment that the graphic designed for better situational awareness is
boring and the truth of the matter is that graphics that effectively
communicate the state of the process to the operator are boring. Through a
limited use of color the operator’s attention can be driven to the point in the
process that has deviated from a normal or expected state. When the system
state is completely within expected norms the process graphics should not
emphasize and draw the operator’s attention to these normal conditions as that
only serves to overload the operators attention. The utilization of animations
should be with the deliberate intent of drawing the operator’s attention and
not just to make an impressive visualization. If operators are being distracted
by spinning pumps or gradient shaded lights when they should be focusing on a
process value drifting outside of operational limits then the HMI is not likely
to result in the improved ability of achieving the business goals or safe
operation. While color should never be the only method used to communicate
a value or state it can be a very effective tool for driving the user’s attention.
To ensure an optimal HMI design it is very important to establish and strictly
utilize color standards. When designing the color standards that will be used
in the HMI application it is very important to prevent an ambiguous use of
colors. If the same color has multiple meanings then the operator will often
become confused about the information that is being communicated. A significant
concern when choosing colors is that color blindness affects as many as 8
percent of men and 0.5 percent of women. A very effective method for combating color
blindness is to leverage a variation of color saturation. While color blindness
affects the hues of the color perceived by the user these people are still
capable of discerning variations in color saturation.
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| Figure 11:Example of Better Color Usage |
When choosing a color
palette one approach is to use only grays unless an abnormal situation is to be
communicated. It is possible to use alternate colors in the palette as in shown
in Figure 12 but it is very important to ensure that the operator be able to readily distinguish a normal state
from an alarm state with no ambiguity. There is no one color palette that is universally
correct for all applications but by following these simple recommendations you
can ensure that your color palette is working for you, instead of against you”.
Source: Krajewski, John (“Situational
Awareness The Next Leap in Industrial Human Machine Interface Design”
 |
| Figure 12 - Alternate Effective Color Palettes |
Are you considering this
approach in your facility today?? Let me know in the comments section below
In the next few posts I will provide a detail
view at other tools and techniques available (actionable alarm management, and
effective design elements) to improve the operations outcomes mentioned above.
Related Links:
- Top 5 trends that currently drive the need of the modern industrial HMI application
- The Impact of Human Error in Industrial Automation
- A Results Driven Approach to improving overall HMI design
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