Understanding human-machine interfaces and the crucial role they play

In today’s rapidly evolving technological landscape, the interaction between humans and machines has become increasingly sophisticated. A crucial component of this interaction is the human-machine interface (HMI), which serves as the bridge between the operator and the machine. This article delves into the essence of HMIs, exploring their functionalities, components and the critical role they play in enhancing user experience (UX) and productivity. We will also discuss the significance of industrial HMIs and recent trends and technologies that are transforming human-machine interaction.

What exactly is a human machine interface?

As the name suggests, an HMI is any type of interface that allows humans to interact with machines, systems or devices. HMI user interfaces are designed for two-way communication, by presenting information to operators and enabling them to enter commands. Despite a common misconception, an HMI is more than just a touch panel. It encompasses a wide range of elements that the operator will touch, see, hear or use to perform functions and receive information. This includes electromechanical buttons, switches, visual and audible status indicators and multilayered touchscreens featuring graphical user interfaces (GUIs) with digital keys.

The purpose of an HMI system

The primary purpose of an HMI is to facilitate efficient and effective communication between the operator and the machine. By providing a user-friendly human-machine interaction, HMIs make it easier for operators to monitor and control machinery, systems or processes. This interaction can range from simple functions, such as turning a device on or off, to more complex operations, such as configuring system parameters or troubleshooting issues. Behind every operator interface, there is usually a programmable logic controller (PLC), which in the case of touch panels can also be directly integrated with the HMI.

Industrial HMI panels

Industrial human-machine interfaces play a vital role in various sectors, including manufacturing, energy, transportation and healthcare. These HMI operator panels are designed to withstand harsh environments and provide reliable performance under demanding conditions.

Applications of industrial HMIs

Industrial HMI panels are used in a wide range of applications, such as:

• Manufacturing: monitoring and controlling production processes, managing machinery and ensuring product quality
• Energy: supervising power generation and distribution systems, managing renewable energy sources and optimizing energy efficiency
• Transportation: overseeing transportation systems, such as railways, subways and airports, to ensure their safe and efficient operation
• Healthcare: managing medical equipment, monitoring patient data and ensuring the safety and comfort of patients
   

Challenges and design considerations for industrial HMIs

Designing industrial HMIs presents unique challenges, including:

• Harsh environments: Industrial HMIs must be built to withstand extreme temperatures, humidity levels, dust and vibrations.
• Reliability: The performance of these interfaces must be consistent and dependable, even if they are in continuous use.
• Security: They must ensure the protection of sensitive data and prevent unauthorized system access, for example through role and permission management.
• Customization: An industrial HMI needs to be tailored to the specific needs of the respective industry and the operational requirements of the facility.
   

Components of an HMI

An HMI panel or system is composed of various hardware and software components that work together to provide a seamless user experience. These components include:

• Touch panels: These are the most common HMI devices today, allowing operators to interact with machines through touch-based inputs.
• Electromechanical buttons and switches: Many HMIs also include physical buttons and switches that provide tactile feedback, especially in environments where touch panels may not be suitable.
• Status indicators: Visual and auditory indicators alert operators to the machine’s status, helping them to quickly assess and respond to any issues.
• Graphical user interfaces (GUIs): GUIs provide a visual representation of the machine’s functions and operations, making it easier for operators to understand and control the machinery.
• Connectivity: The communication channels that connect the HMI to other devices or systems, such as PLCs, sensors and actuators.
   

The key to a successful HMI

How user-friendly an HMI controller will be hinges on a thorough understanding of the user and the context in which the HMI will be used. Before designing an HMI, it is essential to consider the diverse demographics of future operators and their specific needs, capabilities and limitations. This user-centered approach ensures that the HMI will be intuitive, efficient and accessible to all users.

Understanding the user

A well-grounded definition of the user involves analyzing various factors, such as:

• User demographics: educational level, technical proficiency or other factors that may be relevant 
• The user’s role: the specific tasks and responsibilities of the operator, which may vary in line with their position (normal user, administrator, etc.)
• Physical location: the operating environment, including factors such as lighting, temperature, noise and vibration levels, exposure to dust, water and chemicals, and whether the HMI will be used indoors or outdoors
• Tasks to be performed: the specific actions that the operator will need to carry out using the HMI
   

Adopting a user-centered approach

To create an effective HMI, it is crucial to adopt a user-centered approach. This involves:

• Conducting user research: gathering data on user needs, preferences and pain points through surveys, interviews and observation
• Designing for usability: creating an interface that is easy to learn, efficient to use and minimizes the risk of errors
• Prototyping and testing: developing prototypes and conducting usability testing to identify and address potential issues before the final implementation of the HMI
• Iterative improvement: continuously refining the HMI based on user feedback and changing requirements
   

Benefits of a well-designed HMI

A well-designed HMI offers numerous benefits, including:

• Improved user experience: An intuitive and user-friendly interface enhances operator satisfaction and productivity.
• Increased efficiency: Streamlined workflows and easy access to information enable operators to perform tasks more quickly and accurately.
• Enhanced safety: Presenting information in a clear and concise way helps operators to make informed decisions and reduces the risk of errors.
• Better situational awareness: HMIs can provide real-time data and alerts, allowing operators to stay informed about the status of the system and respond promptly to any issues – this is particularly important in today’s factories, with one operator often responsible for multiple machines that may not be located directly next to each other.

Advantages of mobile and wearable HMIs

The integration of mobile devices and wearables into HMI systems offers a number of important advantages, including:

• Increased mobility: Wherever operators are in the facility, they can maintain control over the machinery, enhancing their ability to quickly respond to any issues that arise.
• Enhanced situational awareness: Wearables provide operators with alerts and important data in real time, allowing them to stay up to date about the machine’s status and performance.
• Improved efficiency: Mobile devices and wearables streamline operations by providing easy access to information and control functions, reducing the time and effort required to manage machinery.
   

Future HMI trends

As technology and user needs continue to evolve, so, too, do the capabilities of HMIs. A number of recent or emerging trends are set to transform operator interfaces, making them more intelligent and adaptive:

• The full rollout of Industry 4.0 involves the connection of HMIs with the Internet of Things (IoT), or more specifically, the Industrial Internet of Things (IIoT), to enable real-time data exchange and remote monitoring. This in turn facilitates advanced analytics, which can be used for predictive insights and to optimize system performance.
• Artificial intelligence (AI) and machine learning (ML) enable HMI systems to learn from user interactions and adapt to individual preferences. This results in more personalized and efficient interfaces that anticipate the needs of the operator. For example, AI-driven HMIs can analyze historical data to predict potential issues and provide predictive maintenance recommendations, reducing downtime and enhancing productivity.
• Augmented reality (AR) and virtual reality (VR) are set to revolutionize the HMI experience by making it more immersive and interactive. AR can overlay digital information onto the physical environment, enabling operators to view data and instructions directly within their field of vision. And with VR, it becomes possible to simulate complex scenarios, so that operators can practice and refine their skills in a safe and controlled environment.
• Voice recognition and natural language processing (NLP) technologies are now also being integrated into HMIs, allowing operators to control machinery simply by issuing voice commands. This simplifies operations and reduces the need for physical, “hands-on” interaction with the interface. Voice-enabled HMIs can also provide verbal feedback, enhancing communication and improving the overall user experience.
• Biometric authentication, including fingerprints and facial recognition, can enhance the security and usability of HMIs. These technologies ensure that certain machine control functions can only be accessed by authorized personnel, reducing the risk of unauthorized use and improving the safety of operations.