HMI
Automotive human-machine interface (HMI) solutions are features and components of car hardware and software applications that allow drivers and passengers to engage with the vehicle, as well as the outside world. It gives users smarter, safer, (and more enjoyable) driving experience. Automotive HMIs allow drivers and passengers to interact with their vehicles in a far more natural way. Via in-car touch screens and buttons, push rotary controllers, swipe and gesture functions, and even speech recognition technology.
Industries using HMI include:
HMI technology is used by almost all industrial organizations, as well as a wide range of other companies, to interact with their machines and optimize their industrial processes.
List of industries using HMI are
- Energy
- Food and beverage
- Manufacturing
- Oil and gas
- Power
- Auto motors
- Transportation
- Water and wastewater
- And many more
HMI design principles and fundamental blocks:
The three major principles are usability, distraction, and user acceptance. It determines the cognitive ergonomic quality of an HMI in automotive
- Usability is the ease of use of a human-made object. According to Nielsen, usability is one of the key criteria in defining HMI quality and is based on learnability, efficiency, memorability, errors, and satisfaction.
- Distraction is the diversion of attention from the principal activity. While the main task of any HMI is to improve a driver’s user experience, interaction with an in-car infotainment system may result in being distracted from driving. The concept of distraction is closely linked to that of usability: the higher usability, the lower distraction.
- Acceptance is the user’s willingness to use technology for its designed purpose.
The task of HMI designers is to ensure high usability, low distraction, and high user acceptance. And the HMI design principles listed below can help achieve the perfect balance of these criteria.
A balanced approach to functionality selection:
Being particular when choosing features for an in-car infotainment system is critical for high user acceptance rates. All HMIs contain the following elements:
- environment (road condition, weather, traffic sign, pedestrian, animal)
- vehicle (speedometer, tachometer, fuel gauge, warning signals, entertainment)
- social media (stream media, location info, entertainment)
It’s important to first focus on the features that ensure safety and the successful completion of the driver’s primary task: to get from point A to point B. Only after that, you should proceed with additional functionality.
Notably, some of the features that were once considered “additional” are now becoming must-haves. For example, making/receiving calls, navigation, and music/podcasts/audiobooks are insisted on by drivers.
The challenge is in the balance between functional complexity and simplicity of user interaction. Too many features not only decrease user acceptance rates but also negatively affect usability.
NOTE: Conduct additional user research to define what to add and what to omit.
Text on screens:
A lot of text on displays may distract the user from driving, which means that no label should go beyond one line. This rule, however, doesn’t apply to text that should be read in non-motion situations.
In any case, all text on screens should be precise and comprehensive.
It will help users to be 100% certain of what to do next, which particularly applies to critical situations that require immediate action. Visualization and graphical representation drastically improve the ease of use. The icons replacing labels can be a simple solution,
Also, when “drafting” the design of a head unit and other screens, don’t underestimate the font size. Given that the average distance from the eye to the main display is about 60 cm/24 inches, the font size shouldn’t be less than 5.3/6 mm.
Minimize the number & complexity of actions:
Speaking of interaction with the HMI, it is critical to minimize the number of “taps” required to complete each task. A minimal amount of calls to action can decrease distraction and prevent motion sickness, which is more likely to happen when a driver attempts to perform too many tasks while driving.
To ensure each action is completed successfully, it is also crucial to choose interaction types that are easier to perform over more complex ones. For example, single tap options, scrolling, flicking left/right/up/down, etc. are less risky. When it comes to scrolling, you should avoid the free-scrolling function: all scrolling actions should have a snapping effect.
On top of that, it is necessary to balance hard and soft interactions. Hard interactions are actions deliberately performed by a driver, while soft interactions are those performed by the system without input. The right combination of interactions can decrease the distractions of drivers significantly.
Think about the possible ways of interaction:
As drivers interact with the HMI, they usually have tree ways to input data: voice commands, request typing, or handwriting, Gestures To make sure all variants work in a perfect way, it’s necessary to eliminate obstacles that may prevent data recognit
Ambient noise levels while driving may affect speech interpretation. When it comes to typing requests, vehicle vibration, speed limits, a high level of distraction, and low level of input convenience for a left-handed driver make it difficult to hit the keyboard. As for handwriting, it seems to have less obstacles than other methods, especially if implemented correctly. Today, it’s possible to choose destination, change car settings, and even switch over favorite songs with the twist of a finger.
With the natural language processing and convolutional neural network, A Convolutional Neural Network (CNN) is a type of Deep Learning neural network architecture commonly used in Computer Vision. handwriting recognition is possible within the transcription of finger-drawn words into a digital text. Moreover, neural networks help to implement a multi-character recognition (MCR) model for more accurate interpretation. Classical machine learning approaches also allow to apply word suggestion and word correction models that improve word detection.
Colors
In terms of safety in the automotive context, dark mode is preferable as it reduces distraction. However, it doesn’t have to be the only option. The light mode improves readability in many cases, such as using the navigation map. Besides, people with astigmatism find it harder to discern white text on a black background.
When it comes to differing color elements on screens, prioritize safety over aesthetics. Subtle tones are not so important. Instead, “traditional” colors will ensure intuitive user experience, while high contrasts will make text more visible. These rules should particularly be taken into account when considering a head-unit display design.
