Ford has called for standardised light signals to show the intent of self-driving vehicles.

Writing on medium.com, John Shutko, a human factors technical specialist for self driving vehicles at the automaker, said there's currently a tendency to focus most on the customers who will be riding in these vehicles.

"We're working to earn the trust of everyone involved, including all road users and entire communities where self-driving vehicles will be operating," he said.

"For this technology to be successful, it's critical it be integrated into society in a way that makes everyone confident in how it works to serve people and business.

"The idea that pedestrians, cyclists and scooter users should change their behavior to accommodate self driving cars couldn't be further from our vision of how this technology should be integrated. It's why we've been hard at work developing an interface we believe will help self-driving vehicles seamlessly integrate with other road users.

"We're calling on all self driving vehicle developers, automakers and technology companies who are committed to deploying SAE level 4 vehicles – and believe these vehicles should communicate intent – to join us and share ideas to create an industry standard for communicating driving intent, whether it be driving, yielding or accelerating from a stop."

Shutko said the work Ford had already done was now open to others through a memorandum of understanding.

Ford last year worked with Virginia Tech Transportation Institute (VTTI) to conduct a real-world study of a "self driving intent interface", a light bar mounted to the top of a windscreen of a Transit Connect van.

The VTTI team designed a seat suit that concealed an actual human driver to simulate the van operating on its own to determine if the signal patterns communicating its intent were successful.

Three different lighting scenarios were tested, as well as a baseline condition where the lights were off, to observe how pedestrians and other road users responded to the vehicle signaling its intent:

  • Yielding: Two white lights moving side to side to indicate vehicle is about to come to a full stop
  • Active driving mode: Solid white light to indicate vehicle intends to proceed on its current course (although can respond appropriately to objects and other road users in the course of its travel)
  • Start to go: Rapidly blinking white light to indicate vehicle is beginning to accelerate from a stop

Multiple cameras allowed hours of road user response to various signaling of the vehicle's actions over the course of more than 2,000 miles to be observed.

The VTTI team catalogued all the footage and found the light signal interface did not encourage any unsafe behaviour by other road users. The results proved there was a baseline to build from in terms of the potential to improve acceptance of self driving vehicles and trust in the technology.

Using virtual reality, study participants were placed on a street corner to observe and gauge reaction to a complex mix of vehicles driving through an intersection, some equipped with the intent interface light signals and some without. With no prior explanation of what the different signals meant, researchers found it took about two exposures for participants to learn what a single signal meant and between five and 10 exposures to understand the meaning of all three lighting patterns.

Ford is now installing the self driving intent interface on a small fleet of Fusion Hybrid self driving development vehicles to be used by Argo AI in Miami-Dade County. Ongoing testing will continue to expose pedestrians and other road users to the light bar so their reactions can be observed.

Research in Europe will see how the same signals are received there so Ford can ensure they are universally understood across regions and cultures.

Ford continues to work in parallel with the International Organization of Standardisation (ISO) and the Society of Automotive Engineers (SAE) to create a unified communication interface for self driving vehicles. The goal is agreement in three core areas – placement of the signals on a vehicle, design of the signals and the colour of the light signals themselves.