High performance HMIs for increased efficiency and overall process safety
Using high performance HMIs is a powerful way to streamline how operators manage processes and allows them to react to process upsets as efficiently as possible.
Before computers were widely available in manufacturing, operator interfaces consisted of lights, rotary readouts, and control charts. These components were mounted on a wall in the control room, and required operators to physically interact with them to run the process. Early computer graphics were used to shrink the operator interface to fit on a monitor but were rudimentary and made it easy for the operators to be overwhelmed with data.
As computer graphics progressed, and the world at large became familiar with general business computing, industrial graphics followed suit, leading to the 3D rendered process environments common in most human-machine interface (HMI) marketing materials over the past few years. While these graphics look great in a brochure, they can get in an operator's way leading to confusion and additional productivity losses during process upsets.
Process control system complexity
On a parallel path to the advancements in computer graphics, process control systems have become more complex over the past few decades. The amount of data collected from a manufacturing process is constantly growing, and the industry push towards continuous improvement puts more responsibility than ever on process operators.
High performance HMIs are a relatively new design methodology designed to combat the confusion present in HMI applications with enhanced graphics by focusing on situational awareness as a primary motivator behind design decisions. Situational awareness is an operator's ability to understand the information critical to their job at any given time, derive the correct actions, and reduce information overload through the use of simplified graphics by using color and animation only to convey process upsets. The major hurdle in designing high performance HMI systems is that high performance graphics are not conventionally attractive for use as marketing collateral and are not as easy to advertise.
Sound the alarms
In non-high performance applications, normal process conditions are usually some combination of green and red for running or stopped motors, open and closed valves, etc. There might be flashing, animation to show items moving down a conveyor belt, or fans spinning. Colored lines are used to show the different process connections, usually based on the process's piping and instrumentation diagram (P&ID) drawing. When something goes wrong, there might even be a flood of alarms, leaving the operator a pile of information to sort through to find out what the problem is before they can take steps to fix the issue.
Even for someone who is familiar with the process, finding out the root cause of an upset can be a time consuming task. High performance HMI applications are designed to reduce the amount of time spent looking for the root cause. This is accomplished by simplifying the graphics, removing animations, flashing, and color under normal operating conditions. This even extends to accessibility concerns by not relying on color as the sole source of information. In the case of an alarm, different shapes and symbols can be used to indicate the equipment that is not running normally.
When a process upset occurs, the offending portion of the process can be highlighted, immediately drawing the operators attention to it, and increasing their situational awareness to reduce the amount of time it takes to troubleshoot the problem.
High performance HMIs can also be helpful under normal operating conditions by using trends embedded into process object graphics to show conditions over time. They can also use standardized scales to see if a large number of different devices with different operating ranges are in or out of spec at a glance.
High performance development
One benefit to more complex HMI architectures is the introduction of object oriented programming techniques. This approach allows developers to create templates for graphics, scripting, alarms, and communication structures. Using a template approach to developing High performance HMI applications can reduce overall conversion time by building templates for the graphics and scripting that can then be placed in the application along with parameters for each instance of the graphics. If changes need to be made to any of the objects after the application has been developed, they will automatically be applied to all of the objects, saving time and hassle during commissioning and operation.
Many companies are now implementing high performance HMI applications in their facilities. As they see gains in their process efficiency, other companies are taking note. In the past 18-24 months, the tide has started to turn, with high performance HMIs making its way back to the system vendors and is now showing up not only in marketing materials, but also the major vendors are offering graphics, scripting, and even control logic as out-of-the-box templates to further reduce the complexity and learning curve required to implement high performance HMI applications at any facility.
High performance HMI benefits
High performance HMIs are a powerful tool that can make operators more effective, reduce overall downtime and lost-time spent on troubleshooting, and reduce the stress involved in handling process upsets.
By reducing the graphic interface's complexity, high performance HMIs have the added benefit of being able to convey more information than a typical HMI application because it takes less work for the operators to get their bearings with the increased focus on situational awareness.
Alex Marcy, P.E., is the owner and President of Corso Systems, a system integration firm based in Chicago, Ill. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, firstname.lastname@example.org.
- High performance HMIs can make operators more effective, reduce overall downtime and time spent on troubleshooting.
- High performance HMIs can also be helpful under normal operating conditions by using trends embedded into process object graphics to show conditions over time.
- Many companies are implementing high performance HMI applications in their facilities as they see gains in their process efficiency.
What other applications and industries could benefit from high performance HMIs?
See additional stories from Alex Marcy linked below.