Published on September 12th, 2016 | by Steve Hanley0
Tesla Autopilot Upgrade Puts More Emphasis On Radar, Less On Cameras
Tesla Motors released firmwware version 8 on Sunday, which includes an important upgrade to its Autopilot system. Stung by criticism about the death of Joshua Brown in May when his Tesla Model S struck a tractor trailer broadside on a Florida highway, Tesla has gone back to the deawing board and re-invented its world leading autonomous driving system. Starting with version 8, the technology will now rely more heavily on input from radar and less on that from cameras.
In a blog post, Tesla says “the most significant upgrade to Autopilot will be the use of more advanced signal processing to create a picture of the world using the onboard radar. The radar was added to all Tesla vehicles in October 2014 as part of the Autopilot hardware suite, but was only meant to be a supplementary sensor to the primary camera and image processing system. After careful consideration, we now believe it can be used as a primary control sensor without requiring the camera to confirm visual image recognition.”
Tesla acknowledges that the world can look like a strange place to a radar sensor. Radio waves can “see” through rain, fog, dust, and snow, but have difficulty with metal and people. The concave bottom of an aluminum can can actually intensify a radar beam, making it look larger than it really is.
To brake or not to brake. That is the question.
“[T[he big problem in using radar to stop the car is avoiding false alarms. Slamming on the brakes is critical if you are about to hit something large and solid, but not if you are merely about to run over a soda can. Having lots of unnecessary braking events would at best be very annoying and at worst cause injury.
“The first part of solving that problem is having a more detailed point cloud. Software 8.0 unlocks access to six times as many radar objects with the same hardware with a lot more information per object.
“The second part consists of assembling those radar snapshots, which take place every tenth of a second, into a 3D “picture” of the world. It is hard to tell from a single frame whether an object is moving or stationary or to distinguish spurious reflections. By comparing several contiguous frames against vehicle velocity and expected path, the car can tell if something is real and assess the probability of collision.
“The third part is a lot more difficult. When the car is approaching an overhead highway road sign positioned on a rise in the road or a bridge where the road dips underneath, this often looks like a collision course. 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.”
You may remember that Tesla first said that the software in Joshua Brown’s car may have mistaken the tractor trailer for an overhead highway sign. Tesla intends to rely on fleet learning to help solve the dilemma as to whether a large object will pass safely overhead or requires emergency braking intervention.
“This is where fleet learning comes in handy. 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. 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.
“When the data shows that false braking events would be rare, the car will begin mild braking using radar, even if the camera doesn’t notice the object ahead. As the system confidence level rises, the braking force will gradually increase to full strength when it is approximately 99.99% certain of a collision. This may not always prevent a collision entirely, but the impact speed will be dramatically reduced to the point where there are unlikely to be serious injuries to the vehicle occupants.
Taking things to a bit of an extreme, Telsa says the new software will be able to control the vehicle correctly even if a UFO lands on the road ahead in a dense fog. Good to know if you are a Trekkie or a fan of The X Files. And there’s more. Teslas may now be able to see what’s in front of the car driving ahead.
“Taking this one step further, a Tesla will also be able to bounce the radar signal under a vehicle in front – using the radar pulse signature and photon time of flight to distinguish the signal – and still brake even when trailing a car that is opaque to both vision and radar. The car in front might hit the UFO in dense fog, but the Tesla will not.”
Version 8 offers lots of improvments for real world drivers, even in the absence of any alien spacecraft that may be in the vicinity. Here’s the complete list of tweaks.
- TACC braking max ramp rate increased and latency reduced by a factor of five
- Now controls for two cars ahead using radar echo, improving cut-out response and reaction time to otherwise-invisible heavy braking events
- Will take highway exit if indicator on (8.0) or if nav system active (8.1). Available in the United States initially
- Car offsets in lane when overtaking a slower vehicle driving close to its lane edge
- Interface alerts are much more prominent, including flashing white border on instrument panel
- Improved cut-in detection using blinker on vehicle ahead
- Reduced likelihood of overtaking in right lane in Europe
- Improved auto lane change availability
- Car will not allow reengagement of Autosteer until parked if user ignores repeated warnings
- Automatic braking will now amplify user braking in emergencies
- In manual mode, alerts driver if about to leave the road and no torque on steering wheel has been detected since Autosteer was deactivated
- With further data gathering, car will activate Autosteer to avoid collision when probability ~100%
- Curve speed adaptation now uses fleet-learned roadway curvature
- Approximately 200 small enhancements that aren’t worth a bullet point
The Tesla blog post does not say so specifically, but apparently all these upgrades are simply the result of alterations in software. No changes in hardware have been mentioned, so any Tesla built since October 2014 should be able to benefit from the improvements once the version 8 software has been downloaded and installed.
Source and image credit: Tesla Blog