Automatic emergency braking in spotlight
As recent crashes show, it’s far from foolproof
One of the most common semi-autonomous driving features added to cars these days is automatic emergency braking.
This feature stepped into the spotlight in two recent crashes for different reasons, one involving an Uber selfdriving car in Arizona in March and another involving a Tesla Model S in Utah a few weeks ago.
What can it do — and what shouldn’t a driver expect it to handle?
Using a combination of radar and cameras that scan the road ahead, automatic emergency braking, or AEB, is designed to automatically initiate braking when it senses an obstacle and, in some cases and scenarios, will bring the car to a full stop. The key phrase: in some cases and scenarios.
Automakers are unified in their belief AEB can help mitigate accidents typically brought on by distracted driving or a suddenly incapacitated driver. But they’re also adamant — in auto manual warnings and in interviews — AEB not only is far from foolproof but there are many reasons the system may not react as anticipated.
Or as the Tesla owner’s manual puts it when describing aspects of its semiautonomous Autopilot system: “Several factors” could cause AEB to provide “either no braking or inappropriate or untimely braking … Never depend on (AEB) to avoid or reduce the impact of a collision.”
Why doesn’t AEB work flawlessly? Consider that such systems have to be calibrated by engineers to work mostly in an extreme event, typically moments from impact.
Otherwise, if the calibration is too broad, AEB might slam on the brakes for you if it spied a tumbleweed rolling across the highway, or screech to a halt upon seeing a building looming even though the road might naturally curve away from it.
In a number of scenarios, AEB “may not respond,” says Andy Christensen, Nissan’s lead engineer on the company’s ProPilot Assist system. That’s because these systems are trained to not activate due to a false positive.
The speed at which a car is traveling also factors into AEB’s response.
Chistensen calls AEB “a challenge,” mainly because the system has to react to a number of inputs that include other vehicles moving at different speeds as well as roadside objects that may or may not factor into the route.
“(Nissan’s ProPilot Assist tech suite) is really about providing drivers with reduced stress and fatigue when dealing with either bumper-to-bumper traffic or longer drives on an open road,” he says. “But this tech is still in its infancy. We don’t want people to have expectations that are too high.”
That seems to have been the case in Utah, where the driver felt secure enough in Tesla’s Autopilot to ignore dashboard warnings and allow herself to avoid checking in with the steering wheel or pedals for a full 80 seconds before slamming into a stopped fire truck at 60 mph.
The woman suffered only a broken foot, but her incident highlights how some drivers can become overly confident in driver-assist tech with potentially fatal repercussions.