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Self-driving cars

It’s been a while since I last posted an article on this blog, here we go. Recently I came across an article about self-driving cars. It is a topic that is hard to avoid lately. It appears that every automobile manufacturer is investing into research about self-driving cars. The majority of research thereby concerns the communication between “driver” and car, and ethical considerations how to handle safety critical situations. Toyota recently proposed something like a personal assistant in the car that is suggested to communicate with the driver (Source). The communication between a self-driving car and pedestrians or other traffic participants is, at the moment, on a sidetrack of research.

However, this communication is an important part of the driving task in city environments. A driver communicates with other traffic participants to clarify each others intentions and negotiate a safe passage for everybody. For example, a pedestrian might wish to cross a road without traffic light, if there is a traffic jam or heavy but slow flowing traffic on the road. To ensure he/she can pass the road safely, the pedestrian communicates with the driver in front of whose car he/she wants to cross the road. The pedestrian observes the drivers face and ensures that the driver is looking at him/her. The driver, in response, indicates that he/she has seen the pedestrian with a smile, a nod or a hand-signal and slows down the car or increases the distance to the car in front. Then the pedestrian crosses the road safely.

With a self-driving car this communication is lost. There is no driver to communicate with. What does a self-driving car need to deal with such a situation? A solution would be to leave the decision about the next action up to the pedestrian and let the car handle the situation with its pedestrian recognition and emergency brake system, but that might be unpleasant for the self-driving car’s passengers and it would leave the pedestrian with an uncertainty if the car will stop. So a communication would solve the uncertainty and reduce the risk in that situation. To establish a communication between self-driving car and pedestrian, the car would need the ability to recognise that someone wants to communicate with it, e.g. recognising the pedestrian who wants to cross the road. At best, car would then have a set of signals that helps the pedestrian to see its intentions. The car can then interpret the pedestrians answer and adjust its behaviour, e.g. slow down to allow the pedestrian a safe passage.

The self-driving concept car from Volkswagen (VW) has an interesting design that pushes towards natural communication. The designers have taken Don Normans quote, that turn signals of cars are their facial expressions, literally . The concept car’s face could be used to communicate with pedestrians in a natural way, signalling that it recognised the pedestrian (looking at him/her), a nods in response to the pedestrians request to cross the road (moving its eyes up and down), indicating where the car goes (e.g. movement of its eyes) and if it stops (eyes look forward and rad brake light).

A difficulty could be that the car’s face appears to be visible from the front only. In a traditional car, it is possible to see where the driver is looking through the windows at least from both sides. Other signals that help to predict a drivers intentions are indicators, brake light, and the driver’s reflection in the mirror. It is easy to implement indicators and brake light in a self-driving car. The design becomes more challenging to make its behaviour clearly visible from the sides. Perhaps, if the car’s eyes are implemented on front and side, like the indicators in a traditional car. Another challenge lays in the communication itself. Pedestrians can choose from a range of signals to communicate – e.g. smile, head movement, eye contact, and hand signals. A part of a communication involves to understand each others signals. For a natural communication a car would need to learn a range of signals and how to respond to them. Or do we need to learn a sign language to communicate with a self-driving car?

An interesting aspect is how the communication proceeds over time. When pedestrians learned that self-driving cars always brake for them, does that change their behaviour? Would you as pedestrian be more persistent in your attempts to cross a road? Certainly, self-driving cars are an interesting area of research with manifold aspects to consider from a technical and from a human-centred side.






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