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Human Machine Interface (HMI) Explained

Erin Thompson |

Digital transformation in modern industrial operations has increased the need for technology to bridge the gap between human operators and machinery. Human machine interfaces (HMIs) fulfill this role by providing human operators with a way to interact with machines, systems, and processes in industrial environments through various technologies. 

While the HMI market is gaining significant traction today, predicted to grow from $5.82 billion to $11.60 billion by 2030, the evolution of HMI actually traces back to the mid-20th century, when manual controls dominated industrial settings. Today, these interfaces range from simple push-button panels to sophisticated touchscreen displays, offering intuitive control and monitoring capabilities.

In this article, we’ll uncover everything you need to know about HMIs including its components, functions, and benefits in the industrial world that make it an essential technology and cornerstone of Industry 4.0.

Table of Contents

Table of Contents

Frequently Asked Questions

What is an HMI?

An HMI, or human machine interface, is a technology that allows human operators to interact with machines or systems more easily. In the industrial world, HMIs serve as the bridge between operators and industrial machinery, enabling control, monitoring, and data visualization to optimize manufacturing processes.

What's the difference between HMI and SCADA?

While both HMI (human machine interface) and SCADA (supervisory control and data acquisition) systems facilitate human-machine interaction in industrial settings, they serve distinct purposes. HMI primarily focuses on providing operators with real-time control and monitoring capabilities at the machine level, whereas SCADA operates at a higher level, overseeing entire industrial processes and collecting data from multiple sources.

Where are HMIs used?

HMIs are utilized across various industries, including manufacturing, automotive, pharmaceuticals, and logistics. In manufacturing, HMIs control and monitor production lines, ensuring smooth operation and quality control. Additionally, logistics companies employ HMIs for warehouse automation, managing inventory more efficiently, and real-time tracking of shipments.

What are the components of an HMI?

The components of an HMI typically include programmable logic controllers (PLCs), control systems, and input/output modules, as well as software applications for data visualization, control, and monitoring. Programmable Logic Controllers (PLCs) serve as the brains behind HMI systems, while control systems regulate processes and equipment. 

Additionally, software applications provide interfaces for operators to interact with machines, and inputs and outputs (I/O) facilitate data exchange between human operators and machinery. Together, these components form the backbone of HMI systems, enabling seamless communication, control, and monitoring.

What are the different types of HMIs?

There are many different types of HMIs that offer unique advantages and cater to diverse operational needs. This includes GUIs which use visual elements such as icons and menus to facilitate interaction with machinery, and touchscreens which allow operators to input commands and navigate menus directly on a digital display.

Furthermore, web-based interfaces enable remote monitoring and control of industrial processes via internet-enabled devices. Lastly, multi-touch interfaces allow users to engage with devices  through multiple simultaneous touch points.

Why are HMIs used?

HMIs are used to streamline human-machine interaction by providing operators with intuitive interfaces for monitoring, controlling, and optimizing machinery and processes in real-time. By offering visualizations of data, alerts, and controls, HMIs empower operators to make informed decisions quickly, which ultimately helps enhance both productivity and safety.  

Additionally, HMIs facilitate remote monitoring and predictive maintenance, which results in minimized downtime and improved equipment reliability.

How does a HMI work?

HMIs are user-friendly displays that serve as the interface between human operators and industrial machinery or systems. It integrates hardware components such as touchscreens and input/output modules with software applications to provide operators with real-time control, monitoring, and data visualization capabilities. Operators interact with the HMI through intuitive visual interfaces, allowing them to input commands, receive feedback, and make decisions based on the displayed information. 

What’s the Difference Between HMI and SCADA?

Before diving deeper into HMIs, it's important to distinguish them from SCADA systems (supervisory control and data acquisition). While they both help operators interact with industrial processes, they serve different purposes. HMIs enable direct interaction with machinery and systems through controls and displays, providing real-time engagement with specific equipment.

In contrast, SCADA systems are software platforms that collect and analyze data from multiple sources, offering a higher-level overview. They integrate multiple HMIs, collecting data across an entire facility network.

Components of Human Machine Interfaces

  1. Programmable Logic Controllers (PLCs): PLCs enable the automation of industrial processes through precise control and monitoring. PLCs act as the brain of the operation, executing programmed instructions to manage machinery and processes.

  2. Control Systems: Control systems in HMIs integrate various sensors and actuators to manage and regulate the behavior of machines and processes. They use feedback loops and control algorithms to maintain desired performance levels. 

  3. Software Applications: Software applications provide the user interface for operators to interact with and control industrial processes. They offer features such as real-time data visualization, alarm management, and diagnostics so that operators can efficiently manage and respond to system conditions in real-time. 

  4. Inputs and Outputs: Inputs and outputs (I/O) facilitate the exchange of data between the operator and the machinery. Inputs include devices like touchscreens and keyboards, while outputs include monitors and LED displays. 

What are the Types of HMIs?

Graphical User Interface (GUIs)

GUI (1) (1)

Graphical user interfaces (GUIs) make it easy for users to interact with industrial systems by using visual elements like icons, buttons, and graphics, rather than text-based commands. They are commonly found on machinery and control panels, allowing operators to monitor production processes, adjust parameters, and troubleshoot issues efficiently and intuitively.


Touchscreen (4) (1)

While GUIs provide a visual interface for users to interact with systems, touchscreens respond to touch inputs on a screen. They provide an interface where users can interact directly with data and controls by simply tapping, swiping, and pinching. 

For example, in a manufacturing plant, operators can use touchscreens to adjust machine settings, monitor production metrics, and troubleshoot issues quickly and efficiently. Touchscreens are often used in environments where real-time monitoring, control, and data visualization are essential, such as along production lines.

Common types of touchscreens include:

  • Capacitive touchscreens: These touchscreens sense touch through electrical charge and are commonly found in smartphones and tablets where users can navigate menus, swipe through pages, and zoom in on images by simply touching the screen. 

  • Resistive touchscreens: In addition, resistive touchscreens detect touch by measuring pressure applied to the screen, where they provide reliable operation in harsh environments such as factories or warehouses. 


web-based HMI (1) (1)

Web-based HMIs leverage web technologies to provide operators with remote access and control to industrial systems from any device with internet connectivity. Unlike traditional HMI systems that rely on dedicated hardware and software, web-based HMIs use standard web browsers, making them more flexible and accessible. Tasks could include remotely adjusting machine settings, scheduling maintenance tasks, or even stopping production.

For instance, our web-based FMS enables users to make remote adjustments of our autonomous vehicles from anywhere with an internet connection.

Multi-Touch Interfaces

multi-touch HMI (1) (1)

Lastly, multi-touch interfaces allow users to engage with devices through multiple simultaneous touch points. Unlike single-touch interfaces, which typically support only one touch point at a time, these interfaces offer enhanced functionality and user experience, allowing operators to manipulate complex data and control processes more efficiently.

An example of a multi-touch industrial HMI is a control panel for a manufacturing plant, where operators can navigate through different process parameters, adjust settings, and monitor real-time data using multi-touch gestures on a touchscreen display.

What are Some Common Functions of HMIs?

Common Functions of HMIs (1)

Push Button Replacement

Human-machine interfaces (HMIs) commonly serve as replacements for traditional push buttons. Push buttons provide a simple and reliable method for operators to initiate commands, control machinery, and interact with industrial processes.

Data Management

HMIs play a crucial role in managing data by collecting, storing, and presenting real-time and historical data from industrial processes. By centralizing data management within HMI interfaces, organizations can more easily track performance metrics and diagnose issues that drive continuous improvement initiatives across their operations.

Overseer Functions

Overseer functions provide operators with monitoring and control capabilities to oversee the performance of multiple industrial processes or systems at the same time. For example, this would include a dashboard displaying real-time status indicators, alarms, and key performance metrics for various production lines within a manufacturing facility. 

What are the Benefits of HMIs in Manufacturing?

Benefits of HMI - Edited (1)

1. Enhanced Productivity

HMIs contribute to enhanced productivity by providing intuitive interfaces that streamline operations, reduce human error, and accelerate task completion. With features such as customizable dashboards and predictive analytics that allow for quick access to critical information and real-time control, HMIs empower operators to make informed decisions quickly and optimize production processes.

2. User-Friendly Operation

As we have explored, HMIs are designed for ease of use. By incorporating easy to understand visual cues and interactive elements, there is a reduced learning curve for operators and minimal training requirements. In fact, at Cyngn, our vehicle’s autonomous vehicles are so easy to use that teams can be trained in just a matter of hours. This ease of use enhances overall efficiency and reduces the likelihood of human errors.

 3. Improved Safety

HMIs user-friendly nature also means that it's less likely for human error to occur, which further boosts safety. In addition, operators can monitor and control processes from a safe distance and gain real-time access to vital safety information, including equipment status, alarms, and emergency procedures.

4. Real-Time Analytics

HMIs allow organizations to tap into a wealth of data instantaneously to identify trends, detect anomalies, and make data-driven decisions on the fly. For instance, Cyngn’s HMI provides analytics on productivity, location, battery life, and cycle time. Plus, predictive analytics algorithms are often embedded into HMIs to enable proactive maintenance strategies, minimizing downtime and optimizing equipment reliability.

5. Cost Reduction

HMIs contribute to cost reduction by optimizing processes, minimizing downtime, and enhancing efficiency. In fact, unplanned downtime can cost manufacturers an estimated $50 million per year. However, HMIs enable predictive maintenance capabilities to help prevent costly equipment failures and unplanned downtime, reducing repair and replacement expenses.

6. Proactive Maintenance

Because HMIs integrate advanced diagnostic tools and predictive analytics algorithms, they help identify early indicators of equipment degradation or impending malfunctions, prompting timely intervention and preventive maintenance actions. 

7. Better Plant Management

HMIs offer clear insight into production processes, helping organizations monitor equipment performance and resource use efficiently. With easy-to-use interfaces and real-time data, they not only enable smarter decisions, but also better resource allocation. 

HMIs in Factory Automation

Human Machine Interfaces on Automated Guided Vehicles (AGVs) and Automated Mobile Robots (AMRs)

In industrial settings, HMIs are increasingly integrated into automated guided vehicles (AGVs) and automated mobile robots (AMRs) to enhance operational efficiency. For instance, operators can use the touchscreen control panels commonly found on both AGVs and AMRs to input commands, such as starting, stopping, or re-routing vehicles. In addition, HMIs commonly allow workers to more easily monitor a vehicle's status, battery levels, current location, and other key information on a digital map. 

Human Machine Interfaces Today

HMI Today (1)

Cyngn Insight, our autonomous fleet management system, is thoughtfully designed to be simple and straightforward to operate, and therefore it plays a crucial role in optimizing efficiency. Through Cyngn Insight, workers can easily create, edit, and deploy missions to the vehicle and monitor their fleet in real-time. 

Organizations can access this HMI from anywhere, including:

  1. Through the touch of a button using the on-vehicle display..  
  2. By calling a vehicle to your station from a touchscreen tablet. 
  3. Creating, editing, and deploying missions remotely at your desk.

We have found that these well-designed HMIs have been beneficial to our customers and have played a key role in:

  • Easier adoption of AVs 
  • Removing barriers to operational infrastructure
  • Empowering workers to deploy vehicle missions instantly
  • Streamlining training processes and faster time to productivity

Future of HMI Solutions in Industry 4.0

Edge-of-Network HMI and Cloud HMI

Edge-of-network HMI and cloud HMI are expected to play crucial roles in industrial automation. Edge-of-network HMI systems enable data to be accessed remotely on field devices, enabling real-time decision processing and control at local events. 

Cloud HMIs, on the other hand, facilitate remote monitoring, data analytics, and centralized management of industrial systems. 

Augmented Reality (AR) and Virtual Reality (VR)

Augmented reality (AR) and virtual reality (VR) are revolutionizing HMI systems, offering immersive and interactive experiences in industrial settings.

AR, which is commonly seen in augmented reality glasses, overlays digital information onto the physical environment, providing operators with real-time data and instructions directly within their field of view 

VR, on the other hand, creates entirely virtual environments, enabling realistic simulations for training, design, and remote collaboration. 

Remote Monitoring

Remote monitoring is enabling operators to monitor and control industrial processes from anywhere in the world. Leveraging internet connectivity and cloud-based platforms, operators can use HMIs to access critical data, alarms, and performance metrics on web-based and mobile HMIs. This helps increase operational flexibility but also facilitates faster response times to issues.

New HMI Interaction Types

Advanced technologies are also introducing new ways for operators to interact with industrial systems. Gesture recognition, voice commands, and haptic feedback are just a few examples. These new HMI interaction types enhance user engagement, streamline workflows, and improve operator safety and efficiency in many different manufacturing applications.

Mobile HMI

Similar to web-based HMIs, mobile HMIs empower operators to monitor and control their operations remotely using smartphones or tablets, including accessing real-time data, alerts, and equipment performance. 

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