American electric car maker Tesla Motors is rolling out a new version of its controversial Autopilot functionality that aims to increase safety by relying more on radar than optical camera.
Tesla Motors CEO Elon Musk introduced Autopilot Version 8 on Sunday, claiming that the modifications involved would have prevented a tragic crash in May this year that killed a Tesla car driver and superfan on a highway in Florida.
While radar has been part of the sensor package for Tesla Model S since October 2014, in the original Autopilot it has been used only as a complementary source of information with a camera and an elaborate image processing system being the main driver.
The new Autopilot will also be stricter with drivers if they over-rely on the functionality and its hands-off mode. While the US National Highway Traffic Safety Administration (NHTSA) is still investigating the May tragedy, early reports by witnesses at the crash scene suggested the driver may have been watching a film while hurtling on the highway. Named as tech entrepreneur Joshua Brown, the driver - as well as the Autopilot mode of his Tesla Model S car - overlooked a white tractor trailer performing a u-turn on the highway, set against a pale sky.
According to Musk, Autopilot 8 will sound an alarm when a driver keeps his or her hands off the wheel for more than a minute when travelling at more than 72km/h and when not following another vehicle. When there is a vehicle ahead of the Tesla, the Autopilot will sound an alarm after three minutes of hands-off driving.
If the driver ignores three audible warnings in an hour, the system will temporarily shut off until it is parked, Musk said, adding that new Tesla drivers are less likely to overuse the functionality than the seasoned ones.
When explaining the switch from an optical camera to radar in a blog post, Tesla Motors said it was "a non-trivial and counter-intuitive problem, because of how strange the world looks in radar."
Radar sees easily through fog, dust, rain and snow but can struggle with some objects that appear clear to a human eye or an optical camera. Radar can see through wooden objects or painted plastics, but may overestimate the size of some metallic objects, especially those with a concave shape.
“A discarded soda can on the road, with its concave bottom facing towards you, can appear to be a large and dangerous obstacle, but you would definitely not want to slam on the brakes to avoid it,” Tesla said.
Similarly, an overhead highway road sign positioned on a rise in the road or a bridge could be easily misread as a dangerous object on the road. “The navigation data and height accuracy of the GPS are not enough to know whether the car will pass under the object or not. By the time the car is close and the road pitch changes, it is too late to brake,” Tesla said.
To decrease the number of false alarms, which could not only discourage users but also jeopardise safety, Tesla’s radar images the world around every tenth of a second. The Autopilot 8 software compiles the data into a 3D picture and compares individual frames against the vehicle’s velocity and expected path. “The car can tell if something is real and assess the probability of collision,” said Tesla.
Autopilot 8 is also capable of learning. As the whole system is cloud-based, it can harness the learning capabilities of a whole fleet.
“Initially, the vehicle fleet will take no action except to note the position of road signs, bridges and other stationary objects, mapping the world according to radar," Tesla described. “The car computer will then silently compare when it would have braked to the driver action and upload that to the Tesla database. If several cars drive safely past a given radar object, whether Autopilot is turned on or off, then that object is added to the geocoded whitelist.”
The radar system used by Tesla can also bounce the signal under a vehicle in front, basically allowing the car to see ahead, which comes in particularly handy in low visibility conditions
“The car should almost always hit the brakes correctly even if a UFO were to land on the freeway in zero visibility conditions,” Tesla said.
Despite the new features, Tesla’s CEO Elon Musk asserted that absolute safety is a utopia.
"Perfect safety is really an impossible goal," Musk said. "It's about improving the probability of safety. There won't ever be zero fatalities, there won't ever be zero injuries."
The software update will be available to Tesla Model S owners "over-the-air" in a week or two.
Tesla was criticised by other industry experts for rushing the roll-out of Autopilot last year. The feature is only considered a driving aid. Tesla defended the feature following the Florida crash.