Tesla Motors suspects the automatic braking system on a Model S car involved in a fatal crash either did not detect the lorry it struck, or saw the vehicle and failed to act, company representatives are said to have told congressional aides probing the accident.
The braking system’s radar and camera may have failed to detect the tractor-trailer, Tesla representatives said during a briefing to senate commerce committee staff members looking into the crash, said a committee official familiar with the discussion.
Alternatively, the braking system’s radar may have detected the trailer but discounted it as part of a design to disregard overhead structures such as bridges and motorway signs to avoid improperly applying the brakes, Tesla representatives said, according to the person who spoke on condition of anonymity.
The white tractor-trailer turned in front of the car against a brightly lit sky on May 7 near Williston, Florida, according to the car maker.
Members of Congress including the senate commerce chairman John Thune, a South Dakota Republican, and US safety officials have heightened scrutiny of Tesla’s automated driving systems since the crash. The accident killed an Ohio man when his 2015 Tesla failed to react to an 18-wheeler crossing the road, the national transportation safety board said.
Tesla has said the crash was the first known fatality in more than 210 million kilometres of so-called autopilot features, which are available on more than 70,000 vehicles worldwide.
Company representatives view the braking failure as separate from the autopilot function that manages steering, changing lanes and adjusting travel speed, the committee official said.
Khobi Brooklyn, a Tesla spokeswoman, confirmed that the Senate briefing occurred but did not provide further comment.
The driver of the Model S, Joshua Brown of Canton, Ohio, died when the saloon hit the side of the lorry while travelling 15kph above the speed limit on a hmotorway near Gainesville, Florida, federal accident investigators have said. The National Highway Traffic Safety Administration, which is investigating the May 7 crash, has said that the car’s autopilot system was engaged.
Brown, 40, a tech company owner, was using the car’s automatic emergency braking and lane-keeping features at the time, the report from the national transportation safety board said. Those features are part of the vehicle’s autopilot system.
The Tesla struck the underside of the lorry’s 16 metre semitrailer at a 90-degree angle, shearing off the saloon’s roof before it emerged on the other side of the trailer, according to the report.
Tesla is still working to pinpoint what system failures caused the crash and still believes the safety benefits of semi-autonomous driving systems such autopilot far outweigh any risks, the people said.
Representatives of the company also told committee staffers that cross-traffic remains a challenge for automated driving systems, according to the person.
A Tesla spokeswoman confirmed that the meeting took place and said in a statement that the Florida crash fell “within a unique set of circumstances for which the camera and radar were not able to provide the appropriate warning or braking support”.
Tesla has said previously that autopilot was unable to distinguish the white side of the lorry from the brightly lit sky and there was no attempt to brake by either the self-driving system or Brown.
Tesla officials would not answer questions about the company’s relationship with Mobileye, the company that made the camera and computer system for Tesla’s automatic braking, one of the people said. Mobileye said it would end its relationship with Tesla. The company previously has said its system was not designed to spot cross-traffic, but it did not know if Tesla modified the system.
Mr Musk has said Tesla will press ahead with semi-autonomous driving features, which he says will prevent injuries and accidents.
The company says it tells drivers that they must continue to pay attention while autopilot is working and be ready to retake control of the vehicle.
Follow The National’s Business section on Twitter