Human Machine Interface (HMI)

A Human Machine Interface is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the machine which aids the operator in making operational decisions. Examples of this broad concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls, and process controls. A user interface is the system by which people (users) interact with a machine or a process. The user interface includes hardware (physical) and software (logical) components.

User interfaces exist for various systems, and provide a means for:

  • Input, allowing the users to manipulate a system.
  • Output, allowing the system to indicate the effects of the users’ manipulation.

Generally, the goal of human-machine interaction engineering is to produce a user interface which makes it easy, efficient, and enjoyable to operate a machine in the way which produces the desired result. This generally means that the operator needs to provide minimal input to achieve the desired output, and also that the machine minimizes undesired outputs to the human. Ever since the increased use of personal computers and the relative decline in societal awareness of heavy machinery, the term user interface has taken on overtones of the graphical user interface, while industrial control panel and machinery control design discussions more commonly refer to human-machine interfaces.

Other terms for the user interface include originally Cathode Ray Tube (CRT), Video Display Unit (VDU), & Man-Machine Interface (MMI), and later Human-Computer interface (HCI), Graphical User Interface (GUI), and Human-System Interface (HSI).