Articles | Human Machine Interface Explained

Human machine interface is a term used mostly in the manufacturing environment, specifically on the plant floor, where the HMI or Human-Machine Interface is located. In layman's term, an HMI is any device or control which allows humans to operate or control machines and robots. In computing, HMIs are more known as GUIs or graphical user interface, that enables the user to control a program or software. In physical plants, HMIs can be a simple lever or stick, a complicated combination of buttons, an entire computing system or software designed to manage a system. Since the advent of computers, most modern factories have installed HMIs which are computer driven, known as PLCs or programmable logic controllers. Manufacturers of PLC's include Siemens, Allen Bradley and Omron to name a few.

HMIs or Human Machine Interface requires intelligent design and ease of use. It has to be both well-designed to take into consideration many factors, yet at the same time be user-friendly in order to allow operators easy access to the use of the system. The simpler an HMI is to use, the less time and cost is required to train manpower to use the system. In fact, the success of automation largely depends on the HMI being well-designed and well-though out. If operators have trouble using the HMI, then it matters not if the system works perfectly or had been developed exactly to spec. Users won't be able to move or make anything function with an interface that is difficult to operate.

Most systems designers take great pains to make HMIs as easy to use as possible. Many have backgrounds in psychology and customer satisfaction. Most take the time to profile intended users and study target users or potential operators before they design a system from scratch. Many more take potential user's inputs and suggestion before they even start the design process. The best in the field take customer complaints and turn these complaints into solutions which are the new system's strengths and foundation.

Designing a Human Machine Interface takes a keen eye for what works and what does not. It takes great analytical skill as well as an immense amount of creativity. A designer must both be a user and a programmer. He must both understand the needs of a operator and the needs of the executive. It's not enough to please one. A designer must please both. It's not only enough to design a well-functioning system; the designer must also make that system usable for any operator who will use that system, as well as document the system for future reviews and upgrades.

The success of automation and systems integration depends on a Human Machine Interface that does all of the above. A designer's job is to strike a balance between ease of use and system integrity and controllability. As a general rule, the more complex a system is, the more complicated the HMI becomes.