When a product is designed, the Human Machine Interface is one of the most critical design considerations which can present challenges within the development.
When a product is designed, the Human Machine Interface is one of the most critical design considerations which can present challenges within the development. When the user’s opinion of the product hinges on the interaction formed through the HMI, the design of this component forms a critical element of the product.
In this article, Diamond HMI discusses common pain points encountered when designing a human machine interface, and how businesses can resolve these pain points to create complete solutions for their end users.
1) Unclear or Shifting Requirements
When there is uncertainty around the key design considerations such as the number of keys, tactile feedback, IP rating or expected lifespan, it can add last minute changes to the layout or materials necessitating redesigns of PCBs, tooling or housings.
This impacts manufacturing with delays and added cost. To minimise the impact of late design changes, using prototyping, and cross functional design reviews to ensure alignment before the final design.
2) Mechanical Design & Tactility Challenges
Achieving the right force curve, travel and “click” feel can be difficult, with the variability in switches, membrane or capacitive sensors. Considering the application can assist in choosing the right type of keypad for your application to ensure operational efficiency.
Ensuring your keypad is suitable for use with gloves if applicable by adding key travel distances and rim embossing for membrane and rubber keypads and adding haptics for capacitive keypads to ensure the keys can be felt, even while wearing gloves. Diamond HMI can help to advise on design improvements to overcome tactility challenges, no matter the application.
3) Environmental & Reliability Constraints
Failure to consider the operational environment while designing the HMI, can lead to serious reliability issues with production parts. Without sealing considerations moisture ingress can impact switch response, and chemicals or temperature extremes can degrade manufacturing materials.
Therefore, the consideration for the operational environment of the keypad is a key design factor, with the level of sealing and the durability required especially important. Another way to ensure design compatibility is to complete extensive prototype testing, including real life environmental testing, to prevent warranty claims and accelerated ageing.
4) Manufacturing & Assembly Variability
Considering HMI design in the wider product design and how it interacts with the housing can be critical. Differences in tolerance between components within a unit can affect the travel distance or pressure feel, manifesting in key sticking and batch to batch variations. Sticking with defined tolerances, to prevent layer stack up issues and reduction in misalignment, is the best way to prevent variability in performance. Testing should be done in full product housing to ensure that all components are compatible with each other.
At Diamond HMI our design engineers can ensure that the HMI design is suitable for production, eliminating the common pain problems which can exist when key design considerations are not considered.