Self-driving cars are getting smarter, reports show

The Waymo self-driving car is unveiled at Google's offices in San Francisco, Calif. on Tuesday, Dec. 13, 2016. The Waymo self-driving car is unveiled at Google's offices in San Francisco, Calif. on Tuesday, Dec. 13, 2016. Photo: Paul Chinn, The Chronicle Buy photo Photo: Paul Chinn, The Chronicle Image 1 of / 7 Caption Close Self-driving cars are getting smarter, reports show 1 / 7 Back to Gallery

Self-driving cars — especially those from Waymo — are getting smarter and more street-savvy as they rack up more miles on the road.

That’s one finding from Wednesday’s release of annual reports on “disengagements” — times when a driver needed to take control of an autonomous vehicle — required by the California Department of Motor Vehicles for all companies testing robot cars on public roads.

Autonomous cars from Waymo, the recently renamed offshoot of Google, showed a fourfold improvement in their ability to handle tricky situations, according to the report. Cars from most other makers also improved, albeit at slower rates.

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“We’ve been able to make dramatic improvements to our technology because we use each of these disengages to teach and refine our car (that’s why we set our thresholds for disengages conservatively),” wrote Dmitri Dolgov, head of Waymo self-driving technology, in a blog post.

Waymo’s fleet of close to 60 vehicles, which includes its own distinctive bubble cars, as well as converted Lexuses, logged 635,868 miles in California, dwarfing the road time of the other 10 companies that submitted reports. (Overall, Waymo’s cars have driven 2.5 million autonomous miles in four U.S. test cities throughout its history.)

Not every company testing autonomous cars in California saw its disengagement numbers improve. Auto parts suppliers Bosch and Delphi both recorded more frequent disengagements last year than in 2015.

But Glen De Vos, Delphi’s vice president of software and services, said the rising frequency of disengagements was due to changes in the way the company’s cars are programmed to behave. Delphi has been teaching its cars to drive more confidently — more like humans — in a wider variety of circumstances. At first, that will mean more disengagements, he said, but the number should decline over time.

“When we first started driving, we were really conservative,” De Vos said. “If there was a pedestrian in the crosswalk, anywhere in the crosswalk, we wouldn’t go across. ... As you add features, it’s very natural that you initially see a higher disengagement rate.”

Volkswagen said its cars did not drive on California’s public roads. Tesla had the fewest miles, at 530 for the year. Miles driven by Tesla customers using the company’s Autopilot feature — which can steer cars on freeways but requires human supervision — do not count on the state’s reports. Nor do miles driven on test tracks or other closed facilities — such as the GoMentum Station in Concord, where Honda tests its autonomous vehicles.

While 21 car companies now have California testing permits, only the 11 with permits in 2015 had to file reports, which generally cover Dec. 1, 2015 to Nov. 30, 2016. Seven companies filed reports a year ago.

Waymo clarified that its report focused on its interpretation of the DMV requirement. Cars “switch in and out of autonomous mode many times a day” as a routine part of the testing process, adding up to thousands of times a year, Waymo said. Its report includes only those times when a driver needed to take the wheel because the autonomous technology failed or when safety dictated manual control.

Waymo said that happened 124 times last year, or about once every 5,128 miles. That’s four times better than in 2015, when it drove 424,331 miles and a disengagement occurred once every 1,244 miles.

Waymo uses a simulator to replay each disengagement and thousands of variations. That lets it determine which events could have threatened safety and need prompt engineering attention, it said. This figure went from 0.16 disengagements per thousand miles in 2015 to 0.13 last year, it said.

Software discrepancies accounted for 51 of Waymo’s disengagements, followed by an unwanted maneuver of the vehicle (30) and perception discrepancies (20). The remaining handful were due to issues like reckless human drivers in nearby cars, bad weather, emergency vehicles and road construction or debris.

Cruise, the San Francisco startup now owned by General Motors, came in second to Waymo, with 9,776 miles driven from December 2015 through November 2016. It has 25 cars, mainly Chevrolet Bolts with a few Nissan Leafs, with names such as Platypus, Mongoose and Pronghorn.

Unlike the other companies, Cruise has focused on testing its self-driving cars on San Francisco’s crowded streets, rather than on freeways or suburban thoroughfares. The company recorded 181 disengagements, or one in every 235 miles.

“Our engineers have experienced some of the most complex traffic scenarios expected in a dense urban environment, which will improve the safety of our technology as we prepare to launch our autonomous on-demand ride sharing network,” the company said Wednesday in an email to the Chronicle.

Carolyn Said and David R. Baker are San Francisco Chronicle staff writers. Email: csaid@sfchronicle.com, dbaker@sfchronicle.com Twitter: @csaid, @davidbakerSF

When humans took over from robot cars

Eleven companies submitted reports to the California DMV this year on “disengagements” — times when human drivers assumed control of autonomous cars either because the cars’ technology failed or safety was at stake. Honda and Volkswagen are not listed because they didn’t log any miles on public roads. Seven of companies also submitted reports a year ago. All miles were driven within the state.

2016 2016 2016 2015 2015 2015 Company Miles driven Disengagements Miles between disengagements Miles driven Disengagements Miles between disengagements BMW 638 1 638 N/A N/A N/A Bosch 983 1,442 1 857 625 1 GM Cruise 9,776 181 235 239 103 2 Delphi 3,125 178 18 14,207 323 44 Ford 590 3 197 N/A N/A N/A Nissan 4,099 28 146 1,373 99 14 Mercedes-Benz 673 336 2 637 554 1 Tesla 550 182 3 0 0 0 Waymo (Google) 635,868 124 5,128 424,331 341 1,244