How the Human-Machine Interface prepares us for vehicle automation.

A human-machine interface (HMI) is an interface that allows us to interact with a digital system. Whatever HMI we design, we need to enable users to take advantage of everything a system has to offer.

For almost two decades, the personal computer was the first thing that came to mind when we heard about the digital HMI. But the situation has changed and today the HMI is an integral part of many devices that we use on a daily basis: mobile phones, smartwatches, IoT devices and even cars. Automotive HMI design is a relatively new field with specific challenges.

My team has experience designing for large automotive companies such as Mercedes-Benz and Mitsubishi, and we would like to share some of our hands-on experience in designing HMI cars.

What is the GUI?

A car HMI is a collection of functional elements (such as the main unit, instrument cluster, and heads-up display (HUD), as well as interaction media (touch, voice, haptics) that can transform the vehicle into a living space.

A brief history of digital HMIs

Car manufacturers initially introduced digital HMIs in the early 1980s. At that time, the number of features in ordinary vehicles was increasing rapidly. The designers had to provide controls to allow drivers to manage these new features.

They took two different approaches: some of them used analog controls (they add a physical button for each feature), while others added a screen with dynamic content. The first approach was popular among German automakers, while the second was popular among American and Japanese automakers. The 1986 Buick Riviera is an early example of the latter approach. Inspired by the design of airplanes, it allowed users to control radio stations and the climate using a monochrome touchscreen.

1986 Buick Riviera HMI display. Image by Hagerty.
Buick HMI from the 80s
1986 Buick Riviera HMI display. Image by Hagerty.

Another notable example is Nissan’s CUE-X concept introduced in 1985. The system offered colorful touch screens with nice graphics. As you can see, the design and location of the functional controls are very similar to modern vehicles.

Digital human-machine interface – Nissan Motor Company.

The modern HMI is a mixture of a car control center and an entertainment system. It allows users to change climate settings, find a route to a particular destination, or watch YouTube videos.

Why have so many car manufacturers suddenly decided to introduce HMI displays in their vehicles?

The digital HMI has recently become consumer technology. Only a few years ago, the HMI was the prerogative of luxury vehicles.

The main reason for the change is money. It is much easier to integrate a screen into a cockpit and then update the software based on user feedback (as with cellphones) rather than designing a set of physical controls and then having to redesign them entirely in case of problem.

Another reason is market expectations: users expect to see the HMI in the car they buy today.

But these are market reasons, what about human needs?

The HMI has enormous power to improve the user experience for drivers and passengers. Here are some areas where the HMI can be useful:

  • The HMI helps drivers to informed the decisions. The HMI can deliver real-time data to users in an easy-to-use manner. Take electric vehicles, for example. A driver can see the energy consumption in real time based on the force with which he accelerates the vehicle.
  • It can contribute to a safer driving experience. The HMI can inform drivers of dangerous conditions such as when a vehicle is close to the lane limit, and prevent collisions by slowing the car down to avoid accidents.
  • In addition, the HMI facilitates a more natural interaction between the driver and the car. The HMI can establish a more natural interaction between humans and machines. For example, a voice-based system can allow drivers to use common words to control the car.

What to focus on when designing a digital HMI?

In my experience, designing a beautiful and efficient HMI requires considering art and functionality as one. These factors must be equal and work perfectly together for an immersive user experience.

Here are some essential design principles that I want to share with you:

1. Give users a sense of control

A die 10 usability heuristics for user interface design invented by Jakob Nielsen said: “The design should always keep users informed of what is going on, with appropriate feedback within a reasonable timeframe. ”

This applies to any digital system, including HMI design for vehicles. The HMI should always inform users of the current state through appropriate feedback within a reasonable timeframe. This is especially important when a user is driving. Even when a car is avoiding an accident, it should inform the user of what is happening (for example, by displaying a visual alert with sound).

2. Take a “safety first” approach

Digital dashboard in the car
Digital cockpit and entertainment system. Image by You’re here.

The main advantage of HMI systems is that they help us save lives. Modern cars are equipped with many sensors and collect information and then use that information to track driving conditions. In a connected smart city, this makes it possible to monitor situations in real time and prevent collisions and traffic accidents. The system response to conditions can be:

  • Responsive: the system informs the driver of what has just happened, such as low tire pressure or microsleep (eyelids become heavy).
  • Proactive: The system can analyze conditions, predict what could happen and warn drivers of potentially dangerous circumstances. For example, the system analyzes the weather conditions and suggests that users avoid taking a car on a day when the roads are icy.

The capabilities of the HMI are evolving rapidly. Cars are getting smarter and more capable of making important decisions in real time. But we are far from complete autonomy, and we will only see it with a successful HMI.

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