Driverless Cars May Track Pedestrian Body Language
December 29, 2020
Volvo Cars is considering how autonomous cars will communicate with
other road users in a driverless world. This research looks beyond
current Highway Pilot plans, which aims to have cars drive safely on
their own on chosen areas of highway that Volvo has verified as safe. To
design this future, however, Volvo's experts are seeking inspiration
from the past.
"We make no secret about the fact that we see autonomous drive as the
real long-term solution to avoid car accidents and to achieve traffic
safety," says Mats Moberg, Senior Vice President of R&D at Volvo Cars.
However, as is always the case at Volvo Cars, safety is the first
The Volvo 360c autonomous concept car, unveiled in 2018, provides one
possible avenue of future development. It explores the type of
safety-focused communication Volvo Cars believes will be essential to
cars of the future when it comes to sharing the road with other road
users, including other vehicles, cyclists and pedestrians. The design
for the 360c explores a combination of external sounds, lights, and even
subtle movements to communicate the vehicle's intentions to other road
While the Highway Pilot will only be available on highways verified
safe, when future autonomous cars eventually enter environments shared
with pedestrians, cyclists and other road users, the vehicles will need
to navigate all these complexities on their own. Although the
communication is intended for highly advanced cars that won't be
realised for years to come, the inspiration behind it is simple and
age-old: the human body language.
"What we're really after is to give the self-driving car a type of body
language that everyone understands," says Mikael Ljung Aust, Senior
Technical Leader for Collision Avoidance Functions at the Volvo Cars
"If you want to set up a global standard for communication, there are
some basic ground rules you need to follow. One, you need to speak a
language that everybody understands, otherwise it isn't global. Two, it
needs to be fairly quick. You can't have any uncertainties in traffic
Inspired by aspects of such universal human communication, Volvo is
investigating sounds which aim to indicate an autonomous car's
intentions to other road users.
"What we really need is three or four key sounds that tell you what the
car is going to do," says Ljung Aust. "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'."
"For this, we use a low frequency sound, one we as humans naturally
associate with something big. It's a pulse, oscillating very slowly,
which indicates the car is standing still."
This intuitive approach has also inspired the acceleration and
deceleration sounds being proposed by the 360c, which consist of a soft
ticking that gradually increases and decreases in frequency
For a sound that warns a pedestrian of an oncoming car, Volvo was
inspired by a technology used in submarines. The company is researching
a new technology that uses ultrasounds via parametric speakers to "ping"
pedestrians and cyclists with a noise only they can hear, similar to a
However, as with most human communication, sound is most effective when
accompanied by a synchronized visual display. Volvo Cars thus is looking
into the possibilities of replacing the eye-to-eye acknowledgement of
driver and other road users using contextual lights on the car.
the 360c concept car, this is visualised by a light band wrapped around
the car's sides. The band lights up to alert other road users that they
have been "seen" by the car and are thus taken into account by its
safety systems. The same light band synchronises with the car's sounds
to safely and clearly communicate its intentions.
"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," says Ljung Aust. "Thunder and lightning is an easy
While this technology is in the developmental stages, it's all part of
Volvo Cars' efforts to create the safest traffic situations possible. By
tapping into a combination of movement, sounds and light – non-verbal
communications that have been so deeply ingrained in humans for tens of
thousands of years – Volvo Cars hopes to make the intentions of
autonomous cars to be understood quickly, safely and universally in
years to come.