Google: Autonomous cars needed human help
LOS ANGELES — Google’s futuristic self-driving cars needed some old-fashioned human intervention to avoid 11 crashes during testing on California roads, the company revealed this week, results it says are encouraging but show the technology has yet to reach the goal of not needing someone behind the wheel.
With Google’s fleet logging tens of thousands of kilometres each month, the 11 instances would be the equivalent of a car having one event every three years, based on how much the average vehicle is driven in the U.S.
There were another 272 cases in which failures of the cars’ software or onboard sensors forced the person who must be in the front seat — just in case — to grab the wheel during roughly a year of testing.
Though Google did not release detailed scenarios, the problems included issues with the self-driving cars seeing traffic lights, yielding to pedestrians or committing traffic violations. There were also cases where intervention was needed because other drivers were reckless, and several dozen instances of an “unwanted manoeuvre” by Google’s car.
“There’s none where it was like, ‘Holy cow, we just avoided a big wreck,”’ said Chris Urmson, who heads Google’s self-driving car project. During this phase of testing, Google cars usually stay below 55 km/h, although they also drive on highways.
“We’re seeing lots of improvement. But it’s not quite ready yet,” Urmson said. “That’s exactly why we test our vehicles with a steer- ing wheel and pedals.”
Bryant Walker Smith, a professor at the University of South Carolina who closely follows self-driving-car developments, said the rate of potential collisions was “not terribly high, but certainly not trivial.” He said it remains difficult to gauge how Google’s cars compare to accident rates among human drivers, since even the best data underreport minor collisions that are never reported to authorities.
While the problem rate is “impressively low,” a trained safety driver should remain in the front seat, said Raj Rajkumar, an engineering professor at Carnegie Mellon University who specializes in self-driving cars.
According to Google’s report, a driver typically took control within one second of the car asking for help.
Seven companies with permission to test self-driving prototypes on California roads were required to report to the state’s Department of Motor Vehicles instances in which drivers had to take over due to technology problems or safety concerns.
In all, Google reported 341 total safety-related disengagements during 680,000 km of testing, which took place mostly in neighbourhoods near Google’s Silicon Valley headquarters or on the streets of Austin, Texas. Google ran 49 cars between September 2014, when California began formally allowing prototype testing in public, and the end of November.
Google said its cars would have been responsible in eight of the 11 avoided accidents, according to computer modelling the company performed later. In two other cases, its cars would have hit a traffic cone.