Design considerations for effective HMIS

Article#: 00078

Date: 2022-08-22

Author: Radim

Why is a well-considered human machine interface system (HMIS) design important?
HMI systems are the principal point of contact between the user and a machine or a process. The effectiveness of the HMI system can affect the acceptance of the entire system - in fact in many applications it can impact the overall success or failure of a product.

Depending on application requirements, an HMI element can be anything from a panel with a set of electromechanical controls such as a pushbutton, keylock, or rotary switch, to a multi-layered graphical touchscreen interface networked to production and/or corporate systems.

The HMI system is judged by its usability, which includes how easy it is to learn as well as how productive the user can be.
A well-designed HMI System does more than just present control functions and information - it provides an operator with active functions to perform, feedback on the results of those actions, and information on the system’s performance. The key to a successful HMI System implementation requires a well grounded definition and understanding of the operators. Understanding the diverse criteria driving layout, component selection, ergonomics, safety, industry/ international regulations, and a range of other design and manufacturing options and constraints is also absolutely critical to optimal HMI system design.
The goal in designing operator controls is to provide optimal usability, efficiency, and safety. A sophisticated mix of design and layout considerations, such as contemporary style, colour, and tactile response coupled with ergonomic and intuitive operation, create an optimal user experience that determines a customer’s satisfaction with the system.

Which controls and indicators are appropriate for their purpose and easy to use?
Options range from different types of actuator functions and illumination to push buttons, keylocks for security, and emergency stop buttons for safety—all in varying shapes, colours, and sizes to make the HMIS easily operable.
Displays with basic functionality such as display of key data, alarming and system status may also be used.
Functions that are used quite often such as stop/start and quick positioning can be associated with discrete push buttons.
Where water, fuel, cleaning solutions, fine dust, and other materials may come in contact with HMI control panels the corresponding international ingress protection (IP) codes apply.
HMI Systems must also be able to withstand temperature variations, excessive heat and cold, etc., as well as shock, vibration, and high duty cycle.
Controls must also be durable and as tamper-resistant as possible.

From where should the operator be able to control the machine or machine sub-functions?
The panel layout should present controls in the expected order of use, group related controls together and minimize the need for the operator to change positions.

How many functions will be controlled by the interface?
Where a single function might be served by push button, keylock, and rotary switches, multiple functions could require several screen displays to cover operator functions and options.

How and where should the machine inform the operator about normal and abnormal conditions?
Define clear and consistent signaling conventions!
The panel layout and signalling elements should be designed to provide the operator functional groups of related information in a predictable and consistent manner.
The layout should be organized so that the operator is clearly prompted in advance when the next operator action is required.

What kind of visual, auditory, or tactile feedback will best serve the operator in performing the defined functions?
Feedback is critical to ergonomic industrial design!
Make sure the results of pressing a control button, toggling a switch, or entering a command are absolutely clear.
Determine if operator feedback is visual, auditory, tactile, or a combination of multiple techniques.

Which standards apply – industry, safety, international?
International standards may affect the placement of components, legend size and colour, emergency stop switch configuration and guards, and other ergonomic factors that improve usability, efficiency, and safety.

Are there safety considerations? Are emergency stop switches required?
Emergency stop switches ensure the safety of persons and machinery and provide consistent, predictable, failsafe control response. Most electrical machines must be equipped with these special emergency shutdown safety devices in order to meet workplace safety and established international and domestic regulatory requirements.

In summary: HMI elements for machine control and signaling must be intuitive, self-explanatory, informative, in the right place, accessible, useful, robust and safe.

Reference:

1. Technical Article - Design Considerations for Effective HMIS; https://eao.com/downloads/

© Radim-Automation, 2020–2025. All rights reserved.
Sharing of this article is permitted with proper attribution (link to the original page).

Related previous articles:

• Safety relays versus safety PLC
• Knowledge gained from a completed project is priceless
• Machine modularization
• Modular software architecture
• Hardware concept
• A good concept = Complete set of suitable solutions
• Are there also any disadvantages?
• Think critically!
• Design machines with a focus on user's abilities and needs
• Learn from your journey!
• Collect all the requirements and sort them!
• Who will operate?
• HMI and PLC applications should grow together
• Do you really want to start with this?
• I can see what you can not see
• More than just start and stop
• Safety first!
• Do the right things and do them right!
• Define test scenarios and test cases continuously!
• Don't make it worse!
• Keep the answers to the question "Why"
• Everything is difficult until it becomes easy
• Realize every good idea ASAP!
• Industrial evolution - Listen to your customers and follow new trends!
• Stay alert!
• Have an expert on hand!
• What does the customer need?
• Don't disappoint your customer!
• Ask questions!
• Develop a sense of responsibility!
• Focus on target!
• Think on paper!
• Check the result!
• Keep it simple!
• Success is not a matter of coincidence
• Good communication is important
• Development is evolution
• Transparency and reliability
• From an idea to a consistent system

Related next articles:

• Clear signals
• Talk to operators
• It doesn't work without sensors
• PLC network diagram
• Keep the documentation up to date throughout the project
• Graphic designer
• High Performance HMI
• HMI - Have a consistent style
• HMI - Don't overdo it with complex design
• HMI is not a web page
• Choosing an HMI display
• HMI layout and correct display size
• HMI layout design
• HMI navigation
• HMI - back and forward navigation buttons
• HMI – Don’t hide anything
• HMI - annoying pop-up windows
• HMI - colors in the visualization
• What makes an HMI intuitive?

Comment#: 00001

Date: 2022-08-22

User: Radim

"Multiple shapes, textures, and haptic response are used to differentiate specific control functions and provide a tactile indicator without the need to look at the controls."
- Technical Article - Design Considerations for Effective Human Machine Interface Systems.
- https://eao.com/downloads/

Comment#: 00002

Date: 2022-09-05

User: Radim

"A product is as good as its weakest link. If the HMI System fails, it is most often perceived as a failure of the core system itself.
Therefore the operator interface should be designed to an even higher level of reliability, because it is the critical link between the operator and the equipment."
- Technical Article - Design Considerations for Effective Human Machine Interface Systems.
- https://eao.com/downloads/

Comment#: 00003

Date: 2022-09-05

User: Radim

"A rotary switch with marked iterations can also be used to provide a quick visual indication."
- Technical Article - Design Considerations for Effective Human Machine Interface Systems.
- https://eao.com/downloads/

Comment#: 00004

Date: 2022-09-05

User: Radim

"Not every HMI would benefit from a capacitive iPhone-like interface, however.
Touchscreens are not a good choice in environments where oil, condensation, or airborne debris can collect on flat surfaces.
In other applications, for example where motion is controlled, a capacitive interface could be less effective than a joystick in providing the operator effective control and tactile feedback.
Pushbutton switches allow also easier manipulation when gloves are worn."
- Technical Article - Design Considerations for Effective Human Machine Interface Systems.
- https://eao.com/downloads/

Comment#: 00005

Date: 2022-09-05

User: Radim

Consider where to place the start, stop, and emergency stop buttons:

From where should a person be able to stop the machine in a normal way and from where must he/she be able to stop the machine in an emergency?

From where can someone start the machine or any of its functions to make sure it's safe? Does he/she need to be able to see the machine in order to start it without risk of injuring people or damaging the machine?

Comment#: 00006

Date: 2022-09-10

User: Radim

"Design from the operator's point of view. Talk with operators directly. Don't ask how to improve the HMI; most won't know, and some comments may lead you down the wrong path. Instead, ask operators what tasks they have to do, and find out what information they need in order to do those tasks easily and successfully. Watch them as they work."
- opto22.com; Building an HMI that works - New best practices of operator interface design (06/04/2021)

Comment#: 00007

Date: 2023-07-14

User: Radim

"A good interface is easy to learn, leads to faster reaction time, safer operations and higher productivity. You deserve a system that is intuitive - one that at a glance you can see what actions need to be taken and is easy to navigate."
- General Electric (2021). Modern HMI/SCADA Guidebook for Efficient Operations.
- https://www.ge.com/digital/lp/modern-hmiscada-guidebook-efficient-operations

Comment#: 00008

Date: 2023-08-10

User: Radim

"The information that should be available on a graphical user interface (GUI) of a machine depends heavily on the type of machine and its application. However, here are some basic pieces of information that are often displayed on a GUI:

1. Status Information: The GUI should display important status information about the machine, such as whether it's powered on or operational, whether it has issues or error messages, and whether all systems are functioning properly.

2. Operational Parameters: Display the current operational parameters of the machine, such as speed, temperature, pressure, voltage, etc. This allows the user to monitor the machine's current state and make adjustments if needed.

3. Process Overview: If the machine is involved in an ongoing process (e.g., manufacturing, processing, analysis), relevant process data and steps should be displayed on the GUI. This helps the operator monitor the progress of the process and identify potential deviations.

4. Warnings and Error Messages: Display warnings or error messages if problems or critical situations arise. This enables the operator to react quickly and take appropriate actions.

5. User Interaction: Provide interfaces for user interaction, such as adjusting settings, changing parameters, or issuing commands. This includes buttons, dropdown menus, text fields, and other elements.

6. Historical Data: A history or log of past events and activities can be helpful for identifying trends, diagnosing errors, or making performance improvements.

7. Documentation and Help Material: Provide user manuals, help tutorials, or links to further information so that users can learn about operation, maintenance, and potential issue resolutions.

8. Visualizations: Depending on the application, charts, graphs, or visual representations of relevant data can be useful for recognizing relationships and trends more easily.

9. User Profiles and Settings: Allow users to create individual profiles and configure specific settings to match their workflow.

10. Safety Information: If the machine could potentially be hazardous, the GUI should display safety instructions, emergency stop buttons, or other safety mechanisms.

11. Contact Information and Support: Provide contact information for technical support or customer service in case users need assistance or support.

It's important to carefully design the GUI based on user needs and the type of machine to ensure a user-friendly and efficient experience."

- https://chat.openai.com (What information should be available in the machine's graphical user interface?)

Comment#: 00009

Date: 2024-07-03

User: Radim

Bear in mind that the operator sometimes operates the system in a panic and needs a short and fast route to the destination and a quick response from the system. The system must inform the operator of what has happened and what is expected of the operator.