Human machine interfaces (HMIs) live up to their namesake by allowing a human worker — or several human workers — to control a machine. Also known as a man-machine interface, an HMI serves as a the control system for a machine. Using the HMI, a human worker can dictate tasks for the connected machine to perform. Below are five facts about HMIs that may surprise you.

#1) Origins Can Be Traced Back to the 1940s

The origins of the HMI can be traced back to the 1940s when batch interfaces were used to control machines. Back then users would punch holes into cards and then feed those cards into a machine, thus dictating the task or tasks for the machine to perform. While HMIs have since evolved, these batch interfaces were among some of the first examples of a working HMI.

#2) Not All HMIs Have a Display

While liquid-crystal display (LCD) and light-emitting diode (LED) displays are common found in HMIs, not all HMIs have a display. The first batch interfaces described above didn’t have a display. Even today, some manufacturers still produce their HMIs without a display. If an application doesn’t require a display, adding one doesn’t offer any value or benefit. On the contrary, it only increases the HMI’s production cost, which is why some manufacturers avoid using a display on their HMI.

#3) HMIs Are Designed to Look and Feel Familiar

You may discover that many HMIs feature a similar layout. This is because manufacturers often design their HMIs to look and feel familiar. If a worker is familiar with the HMI’s layout, he or she will learn how to use it more quickly. Not only does this reduce training costs; it also increases the worker’s productivity by allowing him or her to control the connected machine more accurately and efficiently.

#4) Some HMIs Feature Touchscreen Controls

In addition to physical push buttons, dials, levers and knobs, some HMIs feature touchscreen controls. With a capacitive- or resistive-powered touchscreen panel, workers can control a machine using touch commands. Touchscreen HMIs are often preferred because of their superior level of versatility when compared to non-touchscreen HMIs.

#5) HMIs Emphasize Ergonomics

Ergonomics is a key factor for manufacturers to consider when designing an HMI. If an HMI isn’t ergonomic, workers won’t be able to use it as easily or efficiently. Therefore, manufacturers generally design their HMIs with an emphasis on ergonomics, paying close attention to usability elements like familiarity, responsiveness, consistency, comfort and clarity.