Driverless cars could use lights and sounds to “communicate” with pedestrians

In a move to boost road safety, the self-driving cars of the future may communicate with the pedestrians and cyclists around them through human-inspired modes like intuitive sounds and flashing lights, auto vendor Volvo Cars said Tuesday.

Instead of relying solely on the car’s technology to avoid obstacles, the proposed design would also warn nearby humans of its intended path by using an array of external sounds, lights, and even subtle movements, the Swedish manufacturer said. Volvo is developing the system through its model 360c autonomous concept car, unveiled in 2018 as a platform for testing creative approaches like this safety-focused communication.

Of course, logistics professionals are well acquainted with similar safety tools on existing platforms, such as the backup warning beeps emitted by trucks in reverse gear, or the headlights used by forklifts to warn warehouse employees walking down the same aisle. But Volvo’s planned signals would differ by deploying in reaction to specific targets detected by the vehicle’s sensors, and communicating through a wider vocabulary.

"What we're really after is to give the self-driving car a type of body language that everyone understands," Mikael Ljung Aust, senior technical leader for Collision Avoidance Functions at the Volvo Cars Safety Centre. "What we really need is three or four key sounds that tell you what the car is going to do. One of these sounds is informing the driver or the pedestrians around the car what its intentions are, for example: 'I do not intend to move'."

In Volvo’s plan, such an autonomous car could indicate that it was standing still by emitting a low-toned, slowly oscillating pulse, which the company said humans “naturally associate with something big.” In contrast, the 360c could signal acceleration or deceleration by playing sounds like a soft ticking that gradually increases or decreases in frequency. And to warn a pedestrian of an oncoming car, Volvo is researching ultrasonic marine technology that would "ping" nearby people with a noise only they can hear, similar to a submarine's sonar.

The concept car could also complement those sounds with lights. The 360c uses a light band wrapped around the car's sides that illuminates to alert other road users that they have been "seen" by the car and are thus taken into account by its safety systems. "There is an almost behavioral or ancestral reflex in people that make them jump or at least alert themselves if things happen in two channels at the same time," Ljung Aust said. "Thunder and lightning is an easy example.”

According to Volvo, the research could help prepare for a day when autonomous cars drive not just on pre-approved stretches of safe highway, but also on common streets shared with other users.

Today the road belongs to the runners, walkers and cyclists. Volvo is doing our part to help reduce our environmental impact and help keep people safe. #WorldCarFreeDay pic.twitter.com/9a8jRxMX0j

— Volvo Car USA (@VolvoCarUSA) September 22, 2020