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About Human-Machine Interfaces (HMIs)

About Human-Machine Interfaces (HMIs)

Human-Machine Interfaces (HMIs) make interaction and communication between people and machines possible. HMIs can be as simple as buttons and keyboards or as complex as touchscreens and voice recognition systems. They can also include immersive and interactive technologies like Virtual Reality (VR), Augmented Reality (AR), and Brain-Computer Interfaces. This blog post will explore the concept of Human-Machine Interfaces, their types and examples, and how they are designed and evaluated.

What is a Human-Machine Interface?

Human-Machine Interfaces, or HMIs for short, are the systems that enable communication and interaction between human factors and machines. They are the bridge that connects us with the technology we use daily. You are probably using an HMI right now reading this, such as a computer, a smartphone, or a tablet. These external devices have screens, keyboards, mice, touchpads, speakers, microphones, and cameras that allow you to input and output information.

More advanced and innovative HMIs also use different modalities and technologies, such as voice recognition, gesture control, eye tracking, facial expression analysis, brain-computer interfaces, and more. These HMIs can create more natural and intuitive ways of interacting with machines and more immersive and engaging User Experiences (UX).

Human-Machine Interfaces Elements

Human-machine interfaces, or HMIs, are how humans and computers communicate. They include the hardware and software that translate user input into commands and present results to the user. But how do they work? Let’s find out. The basic components of an HMI are:

● User Interface (UI). It allows users to interact with the machine, system, or device. That can be a physical device, such as a keyboard, mouse, touchscreen, voice recognition system, or a Graphical Interface, such as a window, menu, button, or icon.

● Communication protocol. It enables data exchange between the User Interface (UI) and the machine, system, or device. It can be a wired or wireless connection, such as an Ethernet port, USB port, Bluetooth, Wi-Fi, or cellular network.

● Control logic. It processes the user input and generates the appropriate output. That can be a Software Program, such as an operating system, application, or driver, or a hardware device, such as a microprocessor, microcontroller, or programmable logic controller (PLC).

Human Machine Interfaces Types

1. Graphical User Interfaces (GUIs)

GUIs are computer-based HMIs that use a Graphical Interface to present process data and allow the operator to input commands. GUIs come from software like Microsoft Windows or a specialized HMI software package. Graphical User Interfaces typically use elements such as windows, menus, buttons, icons, and sliders to display information and provide interaction. GUIs work on personal computers, smartphones, tablets, and other devices.

2. Touchscreens

Touchscreens are HMIs that use a touchscreen display to present process data and allow the operator to input commands. They are often in applications where a physical control panel is impractical, such as in environments where space is limited. Touchscreens can be integrated with other devices, such as cameras, speakers, or sensors, to provide additional functionality. Touchscreens are common in mobile devices, tablets, kiosks, ATMs, and industrial control panels.

3. Physical Control Panels

Physical control panels are HMIs that use buttons, switches, and displays to present process data and allow the operator to input commands. They are present in industrial settings where a GUI or touchscreen may not be practical, such as in environments with high vibration levels or dust. Physical control panels can suit specific applications and user preferences. Physical control panels are in machines, vehicles, appliances, and instruments.

4. Web-Based HMI

Web-based HMI uses web browsers to present process data and allow the operator to input commands. They can be accessed from any device with a web browser, allowing operators to monitor and control processes remotely. Web-based HMI can use web technologies such as HTML, CSS, JavaScript, or AJAX to create dynamic and interactive interfaces. Web-based HMI is increasingly present in Cloud Computing, The Internet of Things (IoT), and smart home applications.

Human-Machine Interfaces Trends

HMI is constantly evolving and becoming more advanced and intelligent. Some of the current trends and future directions of HMI are:

Multimodal Interaction. HMI supports multiple input and output modes, such as touch, gesture, voice, eye tracking, facial recognition, haptic feedback (touch sensation), Command-Line Interface, Computer-Human Interaction (CHI), and Brain-Computer Interface (BCI).

Augmented and Virtual Reality. HMI creates immersive and interactive experiences by overlaying digital information on the physical world (Augmented Reality) or creating a simulated environment (Virtual Reality).

Artificial Intelligence and Machine Learning. HMI uses Artificial Intelligence and Machine Learning to learn from user behavior and preferences, provide personalized and adaptive services, generate Natural Language Processing and speech responses (NLP/NLU), recognize emotions and intentions (affective computing), and perform complex tasks (computer vision).

Cloud Computing. HMI connects multiple devices and systems through the Internet, accessing data and services from remote servers (Cloud Computing).

Why are Human-Machine Interfaces Important?

Human-Machine Interface technology is present in almost all industrial organizations and other fields to interact with machines and optimize processes. Using HMI, users can monitor and control devices remotely, visualize data in real-time, diagnose problems quickly, and improve efficiency and productivity. HMI is not only useful for humans but also for machines. Machines can use HMI to communicate with each other and coordinate their actions. For example, in a Smart City, engines can use HMI to exchange information about their status, workload, and performance.


HMI is an essential part of the human-computer loop of interaction that enables humans and computers to communicate. Many types of HMIs differ in their form, function, and application. Every kind of HMI has advantages and disadvantages that you must consider when designing and evaluating. By using appropriate methods and criteria for evaluating HMIs, Interface Designers can assess their usability, User Experience, accessibility, and other aspects that affect their performance and quality.