Does your human-computer interface correctly conform to the principles of human factors engineering?

Does your human-computer interface correctly conform to the principles of human factors engineering?

Does your operator interface terminal cause you pain? I'm not referring to mere disappointment and frustration due to its inability to function properly. I'm talking about real, tangible pain, like any real computer terminal, where an HMI encounters health and safety-related usage issues. When working with HMIs, proper ergonomics isn't generally a primary concern for engineers; however, neglecting ergonomic principles leads to increased operating costs, not to mention eye strain, wrist strain, and sprains.

What is ergonomics? There are many definitions, but essentially it is a rigorous science. Microsoft's Encarta encyclopedia defines ergonomics as: "The science of designing machine products and systems with the aim of maximizing safety, comfort, and efficiency for the people who use them." The Board of Certification in Professional at Ergonomics ( BCPE) calls it "knowledge about a range of things to consider when designing, including human capabilities, limitations, and characteristics." Regardless of the definition, ergonomics plays a crucial role in every HMI application, influencing how operators use the product effectively. More importantly, it addresses injuries caused by non-compliance with ergonomic principles; furthermore, workplace ergonomic injuries can be the root cause of costly employee claims and lost work time.

Ergonomics has its own variations

Ergonomic challenges can arise in various ways for HMI products, including, but not limited to, musculoskeletal and visual difficulties. Bill Martin , Product Manager for PanelView Plus 700/1500 at Rockwell Automation, says, “For HMI devices, there are two ergonomic considerations: glare-resistant screens and easy-to-use buttons. Devices like glare-resistant covers reduce eye strain and are easy to remove or replace when dusty or dirty. Operators use glare-resistant covers not only for eye protection but also for their convenience and ease of maintenance.” He continues, “Many operators use touchscreens because they are easier to use; however, those who prefer buttons do so because they can hear and feel feedback when pressing them, reducing physical and mental stress. Operators don't need to repeatedly press buttons or worry about whether they've made contact.”

Dave Kaley , Product Manager for MobileView at Rockwell Automation, commented on handheld HMIs: "Because the terminal is in your hand, it's important that it's easy to hold and easy to operate. For example, a portable terminal must be comfortable and ergonomically friendly for both left-handed and right-handed users." Kaley advised: "The hand holding the terminal should be in a natural, relaxed position, not in an awkward, bent, or uncomfortable position that could lead to wrist sprains."

NormaDorst , LabVIEW Platform Manager at National Instruments, points out: "An often overlooked area of ​​ergonomics is how to set up alarms. This is a part of ergonomics and deserves sufficient attention. The same alarm cannot be used for every malfunction. The sound must alert the operator, but not to the point of interfering with their reaction time. Many HMIs provide too many pulse and flashing signals, which is not in line with ergonomic design."

The trick of reversible cycle

When selecting and designing any HMI system, the following ergonomic factors should be considered:

■ When making a selection, evaluate the ergonomics and functionality of the chosen HMI product. Is the screen resistant to strong light? Is it easy to operate? Is it ergonomically user-friendly?

■ When using an HMI product, its functionality is similar to that of any computer, and the same warnings and limitations should be examined. Repetitive actions should be minimized. HMIs are open to modification, thus adapting to different needs.

■ When installing any new system, time should be spent understanding the concepts and principles of ergonomics. Ergonomically designed intelligent operation can increase work efficiency and reduce lost work hours, personal injuries, and consequently, employee claims.