Optimising Human-Machine Interface (HMI): the key role of the human factor in automotive technology

Our approach combines KPI-based, objective evaluation with the correlation of subjective perceptions. This allows us to build a holistic picture of the user experience. Our analyses result in new target values and clear recommendations for action, helping our clients to optimally align their products and services with their end users and achieve a brand-specific expression (brand DNA).

If driving functions are perceived as unpredictable or disruptive, this can lead to motion sickness (kinetosis). In such cases, the benefits of driver assistance systems are quickly called into question. Imagine you are driving on the motorway with a highly automated system, and you want to use the time for work activities such as online conferencing or email processing, or for leisure activities such as watching TV or reading. But after a short time, you start to feel unwell. This discomfort prevents the system from being used as it was originally designed and advertised. This phenomenon is particularly prevalent with ADAS functions that allow you to take your eyes off the road during assisted driving.

Motion sickness in the context of automated driving refers to the nausea and discomfort that can occur when there is a discrepancy between the visual impression and the movement of the body. This is particularly the case when passengers engage in activities such as reading or working while the vehicle is driving autonomously. The lack of control over the vehicle and unpredictable driving manoeuvres can disrupt the perception of balance and lead to the typical symptoms of motion sickness. This is particularly problematic when the perception of vehicle movement does not match the body’s expectations – for example, in the case of abrupt steering movements or irregular acceleration and braking.

In order to incorporate these findings into development at an early stage and prevent problems, we carry out extensive studies with test persons, both on simulators and in real driving tests. The resulting data enables us to define requirements and measures for future assistance systems.
We work closely with the Charité in Berlin to bridge the gap between medicine and the automotive sectors. This collaboration enables us not only to develop technical solutions, but also to gain a deep understanding of the physiological and psychological effects of automated driving.

If HMI concepts and controls do not represent a function realistically, this will quickly lead to a lack of acceptance of the driving function. It is therefore crucial to enable HMI concepts and functions to be experienced together in a simulation environment at a very early stage of development, before integration into the vehicle is possible. This should be evaluated by experts such as function and HMI developers, as well as by end customers. In this way, the knowledge gained can be fed directly into the development process and strategic decisions can be made on the basis of the data. This approach leads to a continuous increase in maturity from the concept phase to SOP (start of production) and promotes a human-centred development approach, which ultimately leads to a high level of market acceptance.

Our simulator studies always consist of two parts: an expert evaluation and a customer evaluation. In recent years, we have developed a level model that allows us to compare the results of both groups and correlate them with objective measurement data. Using specially developed KPIs, we convert subjective perceptions into objective data –  and vice versa.
By using static and dynamic driving simulators, these assessments can be carried out early in the development process. This significantly reduces the need for on-road testing and provides the basis for efficiently evaluating a wider range of concepts.

Advanced driver assistance systems (ADAS): Test automated emergency braking systems, lane departure warning systems and adaptive cruise control in controlled environments before they are integrated into real vehicles.

Vehicle dynamics and behaviour: Improve driving stability and safety by analysing vehicle behaviour under different conditions (e.g. different road surfaces, weather conditions).

Human-machine interface (HMI): Test the usability and functionality of your HMI systems, from the layout of the controls to the vehicle’s response to driver commands.

In our experience, the development of HMI systems often does not go hand in hand with the development of the function. As a result, customers may not understand the function correctly due to an inconsistent display on the HMI, and therefore deactivate it. Studies such as our have shown that a well-designed HMI significantly improves the perception and evaluation of the entire driving function. We have found that HMI requirements can always be derived directly from the function. Customers need clear and understandable feedback on what a function does or intends to do.
The subjective evaluation of a function should always include the perception of the associated HMI. A Design Thinking study then enables customers to develop their own ideas and impressions in a creative space and to incorporate them into the development process.

Design Thinking is more than just a development method – it is a way of thinking that puts users at the centre of every development decision. In vehicle development, we use it to bridge the gap between technology, design and user experience. Whether we are designing intuitive human-machine interfaces (HMIs) or developing holistic vehicle concepts, we rely on interdisciplinary teams. Engineers, designers, software developers, market researchers and end users work hand in hand to create creative and user-centred solutions. Scale models and interactive mock-ups help to identify weaknesses and make improvements early on.

Precise and measurable requirements are essential for the development of chassis or functions, for example. Too often, however, these requirements are defined from the engineers’ point of view rather than the users’. This often leads to discrepancies between customer expectations and the actual functional atrributes (functional performance) or characteristics of the overall vehicle. The result: a negative user experience (UX) and lower user acceptance.
However, vehicles should be designed for customers, not engineers. Therefore, the requirements must always be translated from the user’s point of view into the engineer’s language and finally into physical KPIs that the engineers can work towards.

To make the user experience (UX) measurable, we develop a customised metric that reflects the subjective requirements and expectations of the end user (subjective KPIs). The developed UX requirements are then translated into physical target values (objective KPIs) that provide a concrete basis for technical development.
This process ensures that vehicles not only fulfil their function, but also convince users with their features. Our UX KPIs provide engineers with clear, measurable target values – the basis for development that inspires customers.

When it comes to defining functional safety, ADAS, user experience (UX), human-machine interface (HMI) and Euro NCAP requirements, vehicle developers are faced with crucial questions such as these. Developing safe and intuitive vehicles requires a deep understanding of human behaviour in different driving situations.

We conduct iterative studies to analyse how users perceive existing systems or new concepts. Subjects are presented with different scenarios with specific tasks tailored to the respective systems or concepts. Objective measuring instruments are used to precisely record eye and body movements (eye tracking and body motion tracking) to ensure a comprehensive analysis of the results.

The studies provide a sound basis for understanding people’s behaviour and perception when using and operating a function. The data is used to inform functional safety requirements and HMI design.

Benchmarking is changing the way manufacturers develop vehicles. By comparing their own products with those of their competitors, they can identify best practices and innovative trends and integrate them into their own development process. To make informed statements about market position and competitiveness, a neutral evaluation by qualified subjects and a methodical approach are required.

Road tests, simulations and measurements: We evaluate driving behaviour and performance under real-life conditions.

We design and conduct studies around the world in the context of different cultural requirements.

Targeted benchmark studies with real users: These complement the developers’ perspective and provide a holistic view. The focus is always on the needs of real users.

Although HMI technologies are considered essential components of modern driver assistance systems and significantly influence their functionality, in practice the two areas are often developed in parallel and independently of each other. The result is often counterintuitive and cumbersome interaction between the driver and the vehicle function, leading to frustration, uncertainty and misuse. To gain confidence and use advanced driver assistance systems (ADAS) such as adaptive cruise control, lane departure warning systems and automatic emergency braking, the driver needs real-time feedback and clear warnings.

This can be explained simply using the example of the automatic parking function (PMA): if the vehicle passes a parking space for no reason that the driver can understand, they will question the usefulness of the function. However, if the HMI indicates that a parking space has been detected but that it is too small, the driver feels informed and gains confidence in the technology.

At MdynamiX, we consider function and HMI as a unit. Our structured process ensures that the interaction between driver and vehicle is designed to be intuitive, safe and comprehensible:

User-friendly HMI concept: We develop HMI concepts that are consistently tailored to the needs of the user. A key component is the interaction design, which focuses on simple and clear operating procedures.

Iterative concept development: Our experts develop initial designs based on use cases and mental models. These are continually optimised using proven methods such as step-by-step analysis (cognitive walkthroughs).

Complience: We ensure that our HMI concepts comply with international standards and norms, such as ISO 15008/9 or the European ESOP guideline. This ensures safety and compliance.

Usability testing is at the heart of the development process: from the initial concept to the finished function, we test usability at various milestones. We use methods and tools such as eye tracking, mock-ups, driving simulators and user-centred listening labs to collect valuable feedback that feeds directly into the development process.

With our holistic approach, we create HMI concepts that inspire confidence and excitement for modern vehicle functions. We work with you to develop solutions that are perfectly tailored to your users’ needs – for a better user experience and greater acceptance of your technologies.