Automation systems are increasingly capable of producing at faster speeds, more agility, and increased safety, but ultimately the control of these systems falls on human hands through human-machine interfaces. How an operator interacts with an HMI will dramatically affect their ability to react quickly and react properly. The repercussions of an operator behaving otherwise can be machine down, production of out-of-tolerance parts, and damage to equipment to name just a few.
Simple design considerations can be made to best facilitate the correct operator action. The principles may seem simple but the consequences can lead to increased performance from all shop floor personnel and result in significant improvements in manufacturing metrics.
Creating A Style Guide
The best way to achieve an efficient interface is to create a style guide for any future HMI development going forward. As a company's needs will vary depending on what it produces and the variety in their equipment, there is no rigid format to how much or how little should be constrained in the guide. Since the guide is to be used across any future machines, it is important to leave room for customization within the guide as well.
A properly constructed style guide should be able to enable any user to understand the how equipment is performing at any machine within their scope, regardless of its type or source (internal, system integrator, or otherwise). It's important to tailor the guide to the specific needs of the company or facility so that it can be adhered to by internal staff and any partners that the company is working with. The following are some high impact areas that we'd recommend implementing:
1. Solidify Navigation & Mandatory Screens
Creating universal methods of navigation is an easy but essential part of maintaining clarity across devices. It should be easy to transfer between screens and not get lost in a complex tiered structure.
Some information is essential no matter what the actual machine might be doing. So keeping important information near the top or another easy to spot location is always preferable. Next, outlining each screen by core function can be done.
Some examples of this could be individual screens dedicated to alarms, user access level, and a home screen. If the opportunity is there to solidify screens such as these in your style guide, it can be a good way to ensure that these areas don't drift at all from your standard.
2. Outline Colors & Symbols
As amusing as the pink selectors and in-screen scroll bars might be during the design, they likely aren't doing you any favors once they are put into operation.
Follow the processes and states that have come up in previous applications and assign them colors. It is okay to assign colors to non-closely linked functions but do not overlap important things such as giving "extend" and "retract" the same color or making "start" and "pause" similar shades of green.
Using ANSI/ISA standards for instrumentation and identification should be done wherever possible. This creates an easy look up resource for any questions and familiarizes users with a standard that is accepted nationally. Additionally, symbols can be used to convey other types of information very quickly as well. Our eye will naturally find a symbol of a house when seeking the home screen much faster than it would find the work "home" in a sea of text.
In a world of ubiquitous smart phones, we have all already been well trained to react this way. It is great to be able to continue to use this behavior in the industrial world as well.
3. Define Text Size, Fonts, & Units of Measurement
Different developers handling different systems will prioritize text font, style, and size differently. They will also be designing the HMI around a system that they already know quite well from working on the dev team. This may open them up to blind spots from a shop floor perspective. Creating a section to guide developers through the details will help them stay on track consistently. An easy example is using unfamiliar/non-standard abbreviations or forgetting to have the units of measurement for all data shown. It can be deeply frustrating to see a bunch of numbers moving on a display without any units to define their meaning.
4. Create Function Clarity & Proper Spacing
An HMI that is lacking in strong design principles can be much more easy to handle during normal operating times where quirky buttons or confusion procedures can be grumbled about, but tolerated. It is during stressful times that an HMI's design will be an important factor to either compound the problem or facilitate a smooth solution.
Taking the time to assure proper spacing my seem like a want and not a need but the user's finger combined with the display sensing accuracy can make accidental selections common if items are too close together. If things must be tight, then keep important functions far away from each other.
Maintaining a visual queue for display boxes versus entry boxes will also prove useful in quickly reducing stressful moments, as will providing a clear message of transitionary states. The states of "Starting" and "Running" mean two very different things to the workers on the shop floor.
5. Make Notes On Code Naming Conventions & Commenting
As noted above, those developing new systems are usually very informed about its workings and that can create blind spots that become issues once the handover to operations takes place. This cause and effect can also occur when the HMI code resurfaces during advanced troubleshooting, system additions, or code enhancements. These situations can occur months or even years after the initial programming and may be under the scope of a new person or department. Opening code that is well organized, utilizes comments, and stays true to the standard naming convention will cause every programmer to sign a brief of relief.
Accelerate The Process With IAS
Finding the time and resources to build an HMI standard and then deploy it across all factory equipment can be a difficult mountain to climb. IAS is able to engineer solutions that provide performance and clarity 24/7. Does some of production comprise of legacy equipment? Not to worry, IAS has extensive experience handling legacy equipment, upgrading control systems, and working with the cutting edge of what is currently available. Contact IAS today.