The U.S. National Transport Safety Board (NTSB) has released key details of its investigation into March’s fatal accident involving an Uber self-driving vehicle and a pedestrian in Arizona.
The NTSB found that while the modified Volvo XC90’s radar and LiDAR sensors detected Elaine Herzberg as she walked her bicycle across the highway six seconds before impact, but the system had trouble classifying the input — identifying her first as an unknown object, then a vehicle, then a bicycle.
Each ‘new’ detection gave the system different assumptions about her path of travel. The report found that 1.3 seconds before the collision, ‘the self-driving system determined that an emergency braking maneuver was needed to mitigate a collision.’
However, Uber’s self driving system cannot engage the vehicle’s emergency braking system. Uber’s vehicles have this system disabled, with the aim of improving passenger comfort by avoiding erratic vehicle behaviour in the case of false positives — such as a plastic bag or newspaper fluttering into the vehicle’s path that might be detected by the vehicle’s sensors as a different object, for example.
In Uber’s system, this is the point at which a human driver is required to intervene, and in this case the car’s driver was not watching the road at the crucial moment that an intervention was required.
The findings in the NTSB’s report have now made public some of the complexities involved in designing an autonomous driving system, with the accident a tragic consequence of what some have called the ‘deadliest stage’ in self-driving development.
Uber’s system does not seem sufficiently developed to appropriately cope with the complex, unpredictable circumstances of real-world driving, and humans are a poor last line of defence in these scenarios.
Uber’s public roads self-driving program in Arizona remains shuttered, with 300 jobs lost as a result, as it undergoes a ‘top to bottom safety review of its self-driving vehicle program, with former NTSB chair Christopher Hart joining the company to advise Uber on its overall safety culture.
The firm is also reportedly in talks with Waymo, Alphabet’s autonomous vehicles arm, about using its technology in its ride-sharing app, after settling a $245 million dispute over trade secrets. Presumably this could eventually lead to utilisation of Waymo’s self-driving technology within Uber’s revised program, if this comes to fruition.
You can read the National Transport Safety Bureau’s preliminary report on the Arizona accident here.