A system that allows self-driving cars to communicate with people around them has recently been tested by car manufacturer Ford. It involves a light bar that uses light signals to communicate the intentions of autonomous vehicles to other road users and pedestrians.
Human drivers communicate with each other and other road users such as cyclists and pedestrians in many ways. For example, users can use hand gestures and head nods to convey their intentions to third parties. Road users can also try to make eye contact with each other, making it clear that other fellow road users have seen them.
Intentions are harder to assess
However, because an autonomous vehicle does not have a human driver, such signals are not possible. As a result, the intentions of autonomous vehicles are much harder for humans to assess than the intentions of a human driver. This is compounded by the fact that self-driving cars make choices based on algorithms and can draw very different conclusions than humans would, so their movements may be unexpected to humans. However, if road users misjudge and wrongly expect, for example, that an autonomous vehicle has registered their presence, this can lead to dangerous situations.
Ford has therefore been experimenting for some time with a system to improve communication between autonomous vehicles and people. Here, the carmaker is opting for a system that uses light signals to convey the intentions of self-driving cars. These signals are given via a light bar mounted on the roof of a vehicle.
Human driver rendered invisible
During a test in Germany, a Ford Transit Connect was fitted with such a light bar. This vehicle was not self-driving, but was driven by a human driver. To test the system properly nevertheless, this driver was wearing a special suit that made him appear to be part of the vehicle's driver's seat. This made the driver invisible to bystanders and other road users.
The light bar uses flashing white, purple and turquoise light to indicate the vehicle's movements and intentions. For example, during the experiment, various light signals were used to indicate, among other things, that the van was about to pull up, was moving or wanted to give way to another road user or pedestrian.
Ford's experiment in Germany
'Universal communication tool is crucial for trust'
"People need to be able to trust autonomous vehicles. In doing so, it is crucial to develop a universal means of communication. Turning someone into a 'human car seat' was one of the ideas floated. When this idea was floated, there was a silence for a while, but it was soon realised that this was the best and most effective way to measure what we wanted to know," says Thorsten Warwel, manager Core Lighting at Ford Europe.
The system was previously tested by Ford in the United States. During this earlier experiment, it used a light bar that could signal using white light only. The new experiment in Germany was conducted with a modified version of this system, which can also give light signals in other colours. In addition, the way the light bar is attached to the vehicle is different. Whereas in the US experiment, the beam was placed just under the roof behind the windscreen, in the German experiment the light bar had been placed on the roof using roof racks. Also, in the German experiment, the beam was significantly larger.
Ford's earlier experiment in the US
Turquoise light signals are most visible
173 people were surveyed after being confronted with the Transit Connect with light bar. 60% of these people said they thought it was an autonomous car. Users also indicated that turquoise light signals were the most visible and more likely to be seen than white light signals. Compared to purple - which was also tested as a colour - turquoise appears to be less likely to be confused with red, something that can cause misunderstandings.
"Making eye contact is important, but our research mainly showed that users look to see what a vehicle is doing. The next step is to investigate how we can make the light signals even clearer and more intuitive for everyone," says Dr Matthias Beggiato from the Department of Psychology at the university Ford is collaborating with on the InMotion project. This project is partly funded by a €1 million grant from the German Federal Ministry of Transport and Digital Infrastructure. The grant is part of a research programme focused on automation and connectivity in road transport.
Ford also conducted a series of separate tests in which the light bar was mounted in other locations on the vehicle, including in the grill and headlights. However, these tests did not reveal a clear preference for this location.
Safe and Secure Lightning from Mitsubishi
Besides Ford, Mitsubishi Electric is also experimenting with communication via light signals. The Japanese car manufacturer has developed the 'Safe and Secure Lightning' system. This system projects light signals on the ground around the vehicle and on built-in screens inside the car. For example, if a vehicle starts reversing, the system projects arrows on the road behind the vehicle to warn of this. From the direction of these arrows, the vehicle's direction of travel can additionally be deduced, making it clear, for example, that the vehicle is about to make a backward turn.
Mitsubishi's system activates automatically based on the actions of the driver or vehicle. This happens so quickly that bystanders and drivers of other vehicles have enough time to react and anticipate the vehicle's movements, according to Mitsubishi.
Mitsubishi Electric's Safe and Secure Lightning (source photo: Mitsubishi Electric)
Author: Wouter Hoeffnagel
Source: Ford
Source: Mitsubishi
