“Motion sickness will jeopardize comfort in driverless cars”
Reading, working, sleeping – autonomous concept cars promise we will make better use of our time while being driven. But just how realistic are these industry promises? Dr. Cyriel Diels, an expert in comfort experience, warns of an underrated risk that could threaten the success of the technology as a whole.
Passengers need to trust an autonomous vehicle in order to feel comfortable – that is one of Dr Cyriel Diels’ core beliefs. At Car HMI 2017 in April, he said: „Car and user must form a relationship - we need to evolve from Human Machine Interaction (HMI) to Human Robot Relationship (HRR).” Diels, a Human Factors scientist at Coventry University, focuses his research on the comfort experience in driverless vehicles. In an interview with 2025AD, he explains why many people could feel sick in self-driving cars – and why the car industry urgently needs to tackle this problem.
2025AD: Dr Diels, your research focuses on passenger comfort in autonomous vehicles. What fascinates you about the topic?
Dr Cyriel Diels: I think that comfort is going to be the key requirement for future vehicles. The automotive industry is really selling the idea that vehicle automation will allow us to do all sorts of tasks – relaxing, reading, writing. However, the problem is that a lot of those tasks will actually be quite difficult to perform in comfort. For instance, we have to think about passenger safety implications. What happens if you have an accident and your tablet computer is between you and the airbag? A lot of the concepts being developed seem to ignore some very basic things we know from work station design. They can be considered quite naive.
2025AD: Do you think they are naive or is the industry knowingly overpromising?
Diels: If you talk to engineers, they probably wouldn’t agree that within the next 10 to 15 years, vehicles will look extremely different and allow us to do all these things. Even if it were possible, a lot of concepts are designed around technology, rather than people. It’s about putting as many displays in the vehicle as possible without asking: do people actually want to use this?
2025AD: How does interior design have to change to be designed around humans and their comfort?
Diels: You need to start from the perspective: what are comfortable postures? Any deviation from that will take effort and strain the body. That’s much better than putting a display into the ceiling just because it looks cool – not realizing that it’s not in line with a natural position.
2025AD: What challenges arise from the fact that a vehicle is autonomous?
Diels: Mixed traffic conditions will cause several challenges. Unless we segregate the traffic completely, there is no way to prevent conventional vehicles from colliding with autonomous vehicles. So therefore, the safety requirements will not be much different to what we see now. This also has a psychological impact: if we know we are not much safer in our car, than a perception of risk is still present.
2025AD: That would also mean that many of the alternative seating arrangements we see in concept cars would not actually be a safe design for such a car.
Diels: And if you know accidents still might happen, how confident would you be traveling facing backwards?
2025AD: It doesn’t seem media or industry are talking a lot about motion sickness caused by riding in a driverless car. According to you, it’s one of the most striking problems.
Diels: It’s likely to become a much bigger issue – and an absolutely critical one as well. The premise of the technology is that we are able to do something other than driving. This is jeopardized by the fact that we may feel sick. And even if we don’t have full-blown symptoms, even the slightest unwell feeling will completely challenge the user experience.
2025AD: Why might the level of sickness be higher than in a conventional car?
Diels: First of all, as a driver, you are less prone to motion sickness because you know exactly where you are steering. Motion sickness occurs when the sensed motion is different to what we expect to sense. So overall, everybody will become more susceptible as a passenger. Secondly, if we want to engage in non-driving related tasks, this may lead to sensory conflicts. If you read a book while being driven in a car, what you perceive with your eyes is a stationary environment. But what you perceive with your balance system is actually a moving environment.
2025AD: What can be done to reduce the motion sickness?
Diels: First, we need to avoid low-frequency motion patterns, like in stop-and-go traffic. But unfortunately you are also dependent on the traffic around you. Second, we need to allow occupants to anticipate the future motion. If you don’t know where you are going, you are more likely to get sick. Maybe we have to provide additional motion cues – be it auditory, tactile, haptic or visual. And third, we need to design displays that reduce the amount of sensory conflicts. As an example, positioning a see-through or augmented reality display near the line of sight so people are still able to see out of the vehicle.
2025AD: At Car HMI 2017, one of the suggestions was to implement frosted glass into the cars so passengers would not get conflicting motion cues.
Diels: This would only work in certain conditions. Our balance system senses acceleration. So if we are traveling at a constant speed on the motorway, we essentially don’t sense any motion. If you frost the windows, for your brain it would appear that you are in a stationary environment. If you start reading now or sleeping, there is no problem. It’s like being below deck on board a ship. However, if there is any acceleration or deceleration, we induce quite a severe sensory conflict. Moreover, I think people would still at least like to have the option to look out of the window to create trust. And don’t forget that a lot of people actually enjoy looking out of the window.
2025AD: Do you think that we will get more used to those new motion experiences over time?
Diels: We know that people adapt to environments that make them feel sick. If you are aboard a ship, you develop so-called sea legs. Over time, people get used to certain motion profiles after a constant exposure to them. But in road transport, the big difference is that we have a choice. We can actually stop the car, we can change our routes. So that opens up the research question: do people actually adapt under these circumstances?
2025AD: You also research passenger comfort in aviation. What can we learn from that field?
Diels: It starts with the irony that we’ve had passenger vehicles for more than 100 years, but from the beginning they have been designed for the driver. If you look at trim levels, at the budgets of front versus rear: it’s all about the driver experience. It’s understandable if you consider that the average car occupancy in Europe is around 1.2. Why would the industry design for passengers if the car is only used by passengers once in a blue moon? But now we have shared automated vehicles, we have to start from scratch. And one of the industries where the passengers have also been at the forefront is aviation.
2025AD: In the future, car ownership may no longer be the norm. If vehicles are more likely to be shared, how will this affect the interior design of cars?
Diels: There might be situations where we want to be isolated so we have to adopt some sort of cocooning approach. On the other hand, there will be times where interaction is desired – so we have to take more of a stagecoach approach. Flexibility will be key. We need to embrace opportunities, but we need to respect certain basic human requirements. We can’t just wildly come up with ideas and designs.
About our expert:
Dr Cyriel Diels is a psychologist focussing on transport human factors and design. Following his PhD at Loughborough University into self-motion perception and negative side effects associated with simulated and virtual environments, he worked as a research scientist at the Transport Research Laboratory (TRL). Besides research consultancy into driver behaviour and performance, his research focussed on simulation technology and behavioural validity, as well as the evaluation of Human Machine Interactions (HMI). He subsequently joined the HMI group within the research department at Jaguar Land Rover (JLR) working on the development of novel concepts.
In his current position at Coventry University he advises on human factors as part of the automotive and transport design courses, and is leading the automotive human factors research within the Centre for Mobility and Transport. His research focusses on the question how we design for safe and comfortable mobility in a future of shared and automated vehicles which introduces novel interactions between psychological, physical, and physiological factors. He collaborates with a range of automotive OEMs and suppliers and academic institutions both nationally and internationally.
Will motion sickness upset the bold interior concepts many makers of driverless cars have presented? Share your thoughts in the comment section!