10 Principles for Good HMI Design

What makes a good HMI?

The ten BUSSE HMI principles are aligned with the interaction principles of DIN EN ISO 9241-110 and the ergonomic principles for physical input devices defined in DIN EN ISO 9241-400.

Because we understand operating concepts as an interaction between hardware and software, we combine the guidance provided by both parts of the standard with established usability heuristics and our experience from machinery and industrial equipment projects.

The result is a practical evaluation framework for the entire operating concept, from the digital user interface to touchscreens, buttons, joysticks, and other physical controls.

These ten principles also form the basis for evaluating operating concepts as part of our HMI Expert Review.

Ten principles we use to assess operating concepts, clearly explained and illustrated with practical examples.

1. Suitability

Aligned with DIN EN ISO 9241-110
The system is tailored to actual tasks, user groups, and operating conditions rather than displaying every technically available function with equal prominence.

Example: Service technicians require different functions from operators working with the system during daily operation. If the interface presents both groups with the same level of complexity, it becomes unnecessarily difficult to use for at least one of them.

2. Self-Descriptiveness

Aligned with DIN EN ISO 9241-110
Operators can always identify the current system status, available actions, and the next required steps.

Example:An alarm message that only displays an error code forces operators to consult a manual. A clear message with an actionable instruction saves time and can reduce support requirements.

3. Conformity with User Expectations

Aligned with DIN EN ISO 9241-110
The system behaves consistently and follows established interaction patterns. Once operators have learned a particular operating logic, they can apply it in comparable parts of the system.

Example: If swiping left takes operators back in one menu, the same gesture should not trigger a different action in a comparable area of the interface.

4. Real-World Relevance

Added for industrial operating contexts
Terminology, structures, and workflows reflect the language of the operators and the actual machine or system rather than its internal technical architecture.

Example: “Conveyor 3” is usually easier for operators to understand than “Module B / Section 12.” The HMI should reflect the physical system, not the internal system architecture.

5. Error Prevention

Aligned with DIN EN ISO 9241-110
The system helps prevent critical operating errors, limits their possible consequences, and supports operators in identifying and resolving errors.

Example: If a reset action is positioned directly next to the primary action, it may be triggered accidentally, particularly when the interface is operated with gloves. Spatial separation and clear confirmation can help prevent unintended data loss.

6. Standards & Requirements

Supplemented by industry-specific and product-specific requirements
The operating concept takes account of the standards, regulatory requirements, guidelines, and established conventions relevant to the product and its field of application.

Example: Medical devices may be subject to requirements for a structured usability engineering process under IEC 62366-1. The specific requirements that apply to an HMI depend on the product, industry, application, and context of use.

7. Learnability

Aligned with DIN EN ISO 9241-110
The system helps new operators understand its structure and learn frequent tasks quickly and safely. Consistent patterns and appropriate guidance reduce the effort required to become familiar with the interface.

Example: A clearly guided introduction, consistent interaction patterns, and understandable terminology make training easier, particularly in environments with changing personnel.

8. Suitability for Individualization

Aligned with DIN EN ISO 9241-110
Where appropriate, the operating concept can be adapted to different roles, tasks, and levels of experience without compromising consistency or safety.

Example: Experienced operators may benefit from quick access to frequently used functions, while new operators may require more guidance. Role-based views can support both needs within one consistent operating concept.

9. Focus

Supplemented by industry-specific and product-specific requirements
The HMI prioritizes relevant information and directs the operator’s attention to the current task, even under time pressure.

Example: In an emergency vehicle, safety-relevant system states and required actions must remain clearly visible. Secondary information must not distract operators from the task at hand.

10. Operating Comfort

Aliggned with ISO 9241-400
Controls are designed and positioned so that they can be used safely and reliably under real operating conditions, for example while wearing gloves, during movement, or under vibration.

Example: Touch targets that work well under stable office conditions may become difficult to select reliably on a vibrating construction machine. We can investigate these operating conditions using tools such as our Motion Table.

Find out where your HMI stands

Take our short self-check to gain an initial overview of the strengths and optimization potential of your operating concept.

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Your contact person

Evamaria Plehn, Head of Industrial UX & HMI Design

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Prinoth

„BUSSE is our design game-changer for snow groomers! Their UI/UX team elevates not only icons and layout but the entire user experience to a new level. Clear operation turns every ride into a pleasure. Reliable from development to series production, BUSSE is by our side. Their interface, based on precise product research, simplifies operation. Flexible, forward-thinking, and reliable – BUSSE is our satisfaction guarantee!"

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Darda

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Das moderne BUSSE DESIGN+ENGINEERING Headquarter mit großen Glasfenstern wird von innen beleuchtet und hebt sich vom dunkler werdenden Himmel während der Dämmerung ab. Das Bild zeigt architektonisches Design und natürliche Beleuchtungseffekte.