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Top 5 problems with human machine interfaces

23rd September 2015


One recurring problem with HMIs is design. Often difficulties arise because the engineers in the design process aren't end-users and so displays and functionality can be convoluted

A study from 2007 showed that 75% of office workers admit to resorting to physical violence against their computer; the other 25% probably only employed mental abuse. Here, Jonathan Wilkins addresses this disturbing statistic while discussing the top five problems commonly faced when using human machine interfaces

The way that humans interact with machines is changing. The static days of the monolithic monitor are beginning to make way for smaller, portable interfaces that provide the user with much more freedom. As we all know, freedom brings opportunity and when presented with such, humans have the ability to prosper ... or flounder.

With the introduction of tablets into automated processes for monitoring, managers are no longer tied to their desk, but free to roam around safe in the knowledge that all the necessary information is now carried with them. However, this undoubtedly adds an element of distraction that wasn't present before; and the chance of human error increases.

We are now also witnessing a cultural trend towards wearable technologies and interfaces. Whether or not these will find their way into the automated workplace is yet to be seen, but with people already being treated for internet addiction when using Google Glass, this can only add another brightly coloured layer to the distraction sandwich.

Backlit villains

When choosing a HMI, parameters such as display life, picture quality, and display brightness all need to be factored into the process in correspondence to the application. There's no need to get a super bright and or high quality interface if it's only used rarely or for menial tasks.

Brightness often means heat. What you have to remember is that heat seriously affects the life of a backlight and, although some HMI manufacturers try to make bulbs easy to replace, it is more common for the entire unit to be replaced instead. This is obviously more costly and so efforts to reduce overheating and overuse should be made.

Gentle touch

Increasingly, HMIs now feature touch screen technology and, as everyone with a touch screen phone or tablet knows, scratches and general wear are a constant worry. Once screens become worn or heavily scratched their responsiveness is diminished and this generally leads to angry fingers pressing harder and harder.

Where appropriate, screen protectors should be used to reduce the chances of damage.

In an industrial environment it may be better to go for a resistive screen, as it doesn’t contain glass, unlike a capacitive screen, which doesn’t feature a glass element. The very best and most modern hardened resistive screens can be used whilst wearing gloves and offer some of the more advanced functionality of capacitive screens, such as better displays, swipe to touch and improved response speeds.

Simple things

One recurring problem with HMIs is design. Often difficulties arise because the engineers in the design process aren't end-users and so displays and functionality can be convoluted. Bright colours, flashing lights and mountains of numerical data all serve to distract and confound operators, whereas low contrast grey backgrounds with minimal colour, portraying simple graphs or analytics, have been found to be most useful.

Common grievances also include difficulty accessing data, poor ergonomics and even impractical display methods - we've seen problems whereby fonts were too small to be legible!

Poor choice

As always, the right HMI for the right job needs to be chosen carefully, with all the factors that we’ve touched upon here taken into consideration. It's easy to blame computers when things go wrong - at the moment they don't have the required intelligence or the persuasiveness to defend themselves; apart from Siri perhaps.

Ultimately what you need to consider, is that if you buy the wrong key, unlocking the potential of humans and machines working in harmonic unity, is going to be incredibly difficult. And it may even lead to work-place violence between the two.

Jonathan Wilkins is with European Automation, Stafford, UK. 









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