The High Performance HMI Handbook and You - Part 1
ISA-101 started a standard for creating a more effective HMI (Human-Machine Interface) design philosophy. The design style known as High Performance HMI (HP HMI) increases an operator’s reaction time by highlighting only what is important while eliminating superfluous data. This is how HP HMI also improves safety and efficiency. Bill Hollifield was on the team that set up the standard, and also wrote a very in-depth book on the subject matter: The High Performance HMI Handbook, published in 2008.
At Corso Systems, we have found inspiration from this book and use it as a basis for our design approach. The book is an excellent guide for HMI design and implementation. It also describes setting up a design philosophy and style guide standard for your company. The High Performance HMI Handbook is an interesting read littered with wonderful relevant and humorous quotes. Side note: we love how easy it is to create HP HMI style graphics with the Ignition platform. Inductive Automation’s Ignition also encourages using High Performance HMI design and dedicates a wonderful section of their manual to it.
An Outline of The High Performance HMI Handbook
The book has four fundamental sections and an appendix of valuable references and guides to further your understanding. We will cover each section in separate posts.
The History and Current Status of the Industrial HMI
Fundamentals of HMI Design and Best Practices
Design and Implementation of a High Performance HMI
Control Rooms, Abnormal Situation Management, and the Future of the Industrial HMI
The History and Current Status of the Industrial HMI
This section explains why the book was written, the intended audience, and a word of warning about the inevitable debate about HMI design. From our experience at Corso Systems, there is always a balance between best practices and what the customer wants. You can provide technical data, results from human performance studies, and all the reasons why you should design an HMI in a particular way, but ultimately, customer satisfaction is key. We always work to find a happy medium so we know we are providing a better experience for the operators using our systems while also meeting the customer’s wants and needs.
History
A typical Non-High Performance HMI
This airplane cockpit instrument panel is a good example of what inspired high performance HMI (HP HMI) principles
Next, the book covers the history of HMI design from electrical control panels, DCS systems, and early computer graphics. For those of us who entered the industry after the early 2000s, it provides insights into the problems early engineers faced—and how they adapted to the changing technology.
The book also addresses one of the common persistent issues of HMI design: the P&ID (piping and instrumentation diagram) display. Depending on design needs, most P&ID type displays are cluttered and ineffective for providing necessary operational information—unless it’s made even more complex with additional layers of symbols. Often, the operator has no idea what the symbols mean, and the symbols might even be completely irrelevant for day to day operation. Used correctly, P&ID displays can be effective for creating maintenance/engineering specific views for debugging purposes.
Next, The High Performance HMI Handbook describes the cluttered graphical interfaces engineers often develop—and provides a justification for the change in HMI design. The inspiration for HP HMI came from the early avionics panels in small planes. These panels often displayed a limited number of items focused on the most important information the pilot needed to see. They were designed with low-contrast imagery with minimal color usage for important alerts and notifications, so the pilot could react quickly and properly to any impending issue. Similarly, HP HMI design limits the amount of clutter and only uses colors to represent alarms, thus creating more effective displays.
Every project usually has the argument of whether to use green and red to signify the “on or off” operational state of a machine. But, in best practice red should be used only for alarm notifications—so that the eye can catch it quickly and the operator can respond effectively. Instead of "Operating by Alarm", which is ineffective, great graphics allow operators to quickly and accurately determine when something begins to move out of the desired limits so they can act to prevent an alarm instead of reacting to it after it occurs.
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High Performance HMI Best Practices
The idea of the High Performance HMI is that it enables an operator to safely and effectively monitor and manage a process by implementing a system of best practices. HP HMI principles focus on increasing an operators situational awareness to improve their accuracy and response time. HP HMI best practices improves situational awareness by creating four distinct display levels:
Level 1 - Process Area Overview: The main overview display focuses on important items while displaying alarms and alerts in a cogent and easily determinable manner.
Level 2 - Process Unit Control: Sub-processes, variables, and control manipulation for reactions.
Level 3 - Process Unit Detail: Further detailed examination. Individual machine controls, specific alarm displays, and information details.
Level 4 - Process Unit Support and Diagnostic Display: Troubleshooting information, possibly P&ID, and anything else that is not important for operation but necessary for maintenance and management.
These best practices suggest redesigning HMIs focusing on only the most necessary and important information for the operator. The fundamental philosophy is: if you don't need to see it to run the plant, get it off the screen. Unnecessary blinking lights, colors without purpose, and other design “features” that provide distractions instead of information must be removed.
When redesigning a Human-Machine Interface (HMI), the focus should be plain, low-contrast flat imagery. Avoid animations and an overabundance of 3D style graphics. Display only the important process values and use color in a limited way to highlight abnormalities and alarm conditions.
Choose simple layouts that follow the process logically, so the operator can easily interpret the information from their screen and react in the process environment. Create a hierarchical structure to expose more detail as necessary. Lastly, minimize the number of keystrokes or actions necessary to perform a task.
7 Steps For Creating a High Performance HMI
Adopt a high performance HMI philosophy and style guide
Assess and benchmark existing graphics against the the high performance HMI philosophy
Determine the specific performance and goal objectives for controlling the process—and for all modes of operation
Perform task analysis to determine the control manipulations needed to achieve the performance goal and objectives
Design and build high performance graphics, using the design principles in the HP HMI philosophy and elements from your style guide to address the identified tasks
Install, commission, and provide training on the new HMI
Control, maintain, and periodically reassess the HMI performance
Read The High Performance HMI Handbook and You Part 2 for more about the fundamentals of HMI design and best practices. We’ll finish here with a quote from one of my favorite authors that’s quoted in the handbook, "Humans beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so." - Douglas Adams (1952-2001) For a brief overview of HMI types and design check out our Human Machine Interface (HMI) Guide.
Corso Systems can help with all aspects if your Ignition challenges. Contact us to learn more