There are autonomous cars on our roads today, but they require a human at the wheel. Whether it’s only a single feature, like Tesla’s Autopilot, or fully autonomous cars in testing, the law demands a human in the driver’s seat to take over if things go wrong. That might be the most dangerous part of the process.
The time it takes for a human driver to recognize there’s a problem and then do something about it is the “takeover time.” Depending on the situation, there is only a brief window of opportunity for that human to grab the wheel and prevent an accident.
Think for a second about drivers in good, old-fashioned cars like the one likely parked in your driveway. People of varying skills pilot these cars down the road.
There’s the teenager who is still learning to judge traffic and determine the best way to handle complicated situations. There’s the veteran driver, let’s say middle-aged, with solid driving skills and good reaction times who has little problem figuring out what to do no matter the traffic. Then there’s the senior whose reaction times and mental sharpness aren’t what they were back in the day.
Those three drivers will have vastly different takeover times when their autonomous car goes astray. Add in the possibility a driver’s attention is less on the road and more on a conversation or the song on the radio, and that takeover time is even worse.
A recent study published by professors Neville Stanton and Alexander Eriksson of the University of South Hampton studied the problem using a group of 26 men and women between the ages of 20 and 52. They created a scenario where subjects took control during a simulated test at a speed of 70 mph with and without any distraction.
Drivers performed the test twice, once while focusing on driving and monitoring the system and once while reading a newspaper. At intervals of 30 to 45 seconds, they were prompted to take over. The results showed drivers needed between 1.9 and 25.7 seconds to take control from their automated cars.
The challenge for developers is to create autonomous cars that, if they need a driver to take over, give the driver enough time to react. Too short a time, and someone could frantically grab the wheel and swerve or brake, avoiding one accident while causing another. The vast difference in takeover times makes pinpointing the optimum lead time a challenge.
Turns out human drivers might be the trickiest factor in developing safe autonomous cars.