Uber's 2016 switch from self-driving Ford Fusion cars in favour of Volvo SUVs also resulted in a reduction in the number of safety sensors used to detect objects in the road, a media report said.
That decision resulted in a self-driving vehicle with more blind spots than its own earlier generation of autonomous cars, as well as those of its rivals, according to Reuters interviews with five former employees and four industry experts who spoke for the first time about Uber's technology switch.
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The report said the new Uber driverless vehicle is armed with only one roof-mounted lidar sensor compared with seven lidar units on the older Ford models Uber employed, according to diagrams prepared by Uber.
In scaling back to a single lidar on the Volvo, Uber introduced a blind zone around the perimeter of the SUV that cannot fully detect pedestrians, according to Reuters interviews with former employees and Raj Rajkumar, the head of Carnegie Mellon University's transportation centre who has been working on self-driving technology for over a decade.
The news agency said the lidar system made by Velodyne – one of the top suppliers of sensors for self-driving vehicles – sees objects in a 360-degree circle around the car but has a narrow vertical range that prevents it from detecting obstacles low to the ground. It cited information on Velodyne's website as well as former employees who operated the Uber SUVs.
Autonomous vehicles operated by Waymo, Alphabet's self-driving vehicle unit, have six lidar sensors, while General Motors' vehicle contains five, according to information from the companies.
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By GlobalDataUber declined to comment on its decision to reduce its lidar count. In a statement late Tuesday, an Uber spokeswoman told Reuters: "We believe that technology has the power to make transportation safer than ever before and recognise our responsibility to contribute to safety in our communities. As we develop self-driving technology, safety is our primary concern every step of the way."
Velodyne acknowledged that with the rooftop lidar there is a roughly three metre blind spot around a vehicle, saying that more sensors are necessary.
"If you're going to avoid pedestrians, you're going to need to have a side lidar to see those pedestrians and avoid them, especially at night," Marta Hall, president and chief business development officer at Velodyne, told Reuters.
The safety of Uber's self-driving car programme has been is under intense scrutiny since Elaine Herzberg, 49, was killed last week after an Uber Volvo XC90 SUV operating in autonomous mode struck and killed her while she was jaywalking with her bicycle in Tempe, Arizona.
Reuters noted the precise causes of the Arizona accident are not yet known and it is unclear how the vehicle's sensors functioned that night or whether the lidar's blind spot played a role. The incident is under investigation by local police and federal safety officials.
Reuters said Uber's top competitors place multiple, smaller lidar units around the car to augment the central rooftop lidar, a practice experts in the field say provides more complete coverage of the road.
The earlier Fusion test cars used seven lidars, seven radars and 20 cameras. The newer Volvo test vehicles use a single lidar, 10 radars and seven cameras, Uber said.
