The case for more colorful HMI graphics
Although a growing number of operators and industrial engineers note a preference for high performance HMIs, i.e. HMI screens that are predominantly grayscale and only use color to highlight highlights assets or operations that need immediate attention, many industrial HMI users still prefer high-intensity HMI graphics. . Often their intention is to add a touch of realism to piping and instrumentation diagrams (P&ID) and other graphical representations in control rooms.
Such realism also allows machine builders to encode help for operators inside HMIs. As the cost of system memory continues to drop, more and more HMI manufacturers are exploiting economics to offer features such as video clip storage and playback. “Machine builders are quickly embracing this feature to integrate things like operator instructions or machine fault diagnosis videos,” said Clark Kromenaker, product manager at Omron Automation.
A touch of realism on the front faces, for example, can also increase the safety of interaction with a machine. “The operator can adjust the model displayed on the HMI of a set of smart sensors, as if he had opened the control cabinet door and made adjustments to the physical device itself,” explains Kromenaker. “Thus, such a face plate allows for more realistic virtual involvement with parts of the machine without some of the hazards that might be present if the control cabinet door were actually opened.” Such faceplates also exist for recipes and alarms.
Contrary to some operators’ preference for colorful HMI graphics, others point to studies that link improper HMI design to operator error and low productivity. Investigative agencies such as the US Chemical Safety and Hazard Investigation Board have identified HMIs as causal factors in the Texaco Pembroke, Esso Longford, and BP Texas City explosions. And a study commissioned by the US Navy found that users of simple, abstract graphics outperformed users of video game-style graphics by 70%, despite an overwhelming preference among users for the video game look.
As technology advances, it will continue to influence the appearance of HMIs. In fact, advancements in graphics engines and object-oriented engineering are behind the entire minimalist movement. “The concept of situational awareness and ‘cool’ or grayscale graphics aren’t new,” notes Roy Tanner, systems marketing manager at ABB. “In the 90s, they weren’t available on HMIs for distributed control systems. Black was the background of choice as there was no other option.
Despite the proven success of high-performance HMIs, consumer applications of graphics technology are likely to continue to dominate industrial applications and be a proving ground for industry. HMI developers are already trying to build on the experience people have with their tablets and smartphones at home. “Beyond generating a level of comfort in users, this (advanced graphical use in HMIs) can go a long way to perfecting the user experience and shortening the learning curve for machine operators,” observes Eric Reiner, specialist in the industrial PC market at Beckhoff Automation.