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What does the forward-facing radar "see"?

Discussion in 'Model S: User Interface' started by mikeash, Mar 12, 2015.

  1. mikeash

    mikeash Active Member

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    I got my S85 about two weeks ago and have been having a ton of fun with it. One of my amusements has been watching the car skillfully handle heavy traffic using the TACC feature. It's a little more aggressive than I'd like (even set to 7) but it's a wonderful feature that makes dealing with traffic (a near-constant reality here in the DC area) so much nicer.

    I'm a computer programmer and I like to understand how stuff like this works, so naturally I've started wondering just what kind of data the radar sensor provides to the system.

    For example, is it able to scan from side to side? It seems to understand turns to an extent, and stays locked on to the car in front of me even though it's a bit off to the side, rather than switching to the concrete barrier directly in front and bringing me to a rapid halt. Does it provide doppler info, or is it just providing distance measurements? What kind of range does it have?

    One thing I'm particularly interested in from a practical point of view is, how fast can I be going and still have the system safely bring me to a stop before hitting a stopped car in my lane? Does it work all the way up to the top speed of the car, or is there some lower limit imposed by the radar's range?

    If anyone has any info about this, or pointers to where I might find it, I would love to know.
     
  2. LetsGoFast

    LetsGoFast Active Member

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    I don't know but I am similarly curious. The Mercedes system uses two seperate radar bands. A short range unit operates at 24 gHz with a wide field and a long range unit operates at 77 gHz with a narrow field. That system is operational up to 150 mph. I know that Autoliv and Delphi supply radar units to manufacturers, but I don't know which one Tesla sources. It seems to most resemble the Bosch system
     
  3. Jaff

    Jaff Active Member

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    Wish it had seen that speed trap...:crying: ...
     
  4. cgiGuy

    cgiGuy Member

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    I can't speak specifically to the Model S sensors, as I don't have them, but on my Infiniti that had collision avoidance and intelligent cruise I could actually see the "sweeping" motion of the lidar on the front camera screen as I would pull into my garage. It would show on the back wall. I would say it was sweeping about 6-7 times a second. But this system would not stop your car from driving right into a brick wall.. it would only lock onto moving objects. So, you could lock onto the car driving in front of you and it would stop when they stop, but you could drive right into a parked car.

    So, my assumption is that the newer systems have tied in the lidar (or radar?) readings with the optical camera to delineate objects. The videos of the Google car's ability to detect pedestrians vs cyclists vs cars is very impressive.

    [video=vimeo;95417016]https://vimeo.com/95417016[/video]
     
  5. anxman

    anxman Member

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    This is a pretty good video from Mercedes: Mercedess autonomous driving on highway - YouTube

    Mercedes leads the way in most of these features. If you fast forward to around 55 seconds, you can see what the car sees. I found it pretty interesting. I believe when it tags a car or motorcycle in front of you, it's using the radar + camera and the lane guides are using the camera. You can see how it paints lines over the lane markers to indicate curves and identify cars in the lane but past the curve.
     
  6. Lump

    Lump Active Member

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    #6 Lump, Mar 12, 2015
    Last edited by a moderator: Mar 13, 2016
    Elon has mentioned the use of Mobileye & its confirmed in this video so you might find it useful...maybe even future features :wink:

    Published on Jan 16, 2015
    Mobileye Co-Founder, Chairman & CTO Prof. Amnon Shashua talks about the future of computer vision and automated driving at the 2015 Deutsche Bank Global Auto Industry Conference

     
  7. brkaus

    brkaus Member

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    Thank you for sharing this info!
     
  8. mikeash

    mikeash Active Member

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    Yeah, this is great stuff. Much appreciated!
     
  9. Saghost

    Saghost Active Member

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    #9 Saghost, Mar 12, 2015
    Last edited by a moderator: Mar 13, 2016
    Mobileye is just the front vision camera and processing, right?

    I was thinking Tesla was adding that to radar from another vendor and ultrasound from a third (and possibly the rear view caera) to build the car's understanding of the world around it.
    Walter

    - - - Updated - - -

    Out of those three, I'm thinking it is most likely to be the Delphi, actually - just based on what little we know about the sensor unit.

    Bosch would use a circular long range antenna and a pair of square medium range antennae:

    Driver assistance systems - Adaptive cruise control (ACC) - Long-range radar sensor , Mid-range radar sensor , Stereo video camera

    Delphi integrates both functions in to a single rectangular phased array box that's about 7 inches across (including the mounts - about 5 inches of radar face.) Can someone go measure the sensor on the front of an Autopilot car, please? :)

    Delphi Adaptive Cruise Control


    I'm having more trouble pinning down the Autoliv sensor, but it looks like it may be an integrated box similar to Delphi's:

    Radar Systems


    Of the three, Delphi does the best job of sounding like the class leading product with lots of fun features, but it's all PR and I don't have complete specs and test results in front of me. Delphi is definitely using pulse-doppler technology, and it looks like it is handing back distance, angle, and relative velocity for everything that hits the radar's detection threshold settings from what little I can see:

    http://www.delphi.com/docs/default-source/old-delphi-files/7705dce6-d83a-45b7-b378-bd3f732c76e0-pdf

    Just found a bunch more useful data here:

    Delphi ESR v9.21.15 - AutonomouStuff - Your Single Source Supplier for Autonomy Components

    There's a picture showing what the Delphi system is seeing for a sample scene (looks like angle, distance and relative speeds,) and more detailed data on what the Delphi can do. (Still don't know if Tesla is using Delphi - but if not I'd suspect the system they are using has fairly comparable specs.)

    Long range radar is a 20 degree arc out to 174m (~570 ft) updated every 50ms and handling object speeds from -100 m/s to +25 m/s (~220mph closure to ~55 mph separation,) medium range is a 90 degree arc out to 60m (~200ft) updated every 50 ms and handling object speeds from -100 m/s to +25 m/s.

    Further up, they also mention it'll see a person (or a deer, presumably) from 200 feet away. Doesn't help if the deer charges at the corner/side of your car, but it should reduce road kill incidents. :)

    Gotta say, I'm impressed with those specs - we've come a long way in the last couple decades. The car can apparently see changes in speed or closure rate 20 times per second, and ought to have quite impressive reach. It'll be interesting to see just what Tesla manages to conjure up with all of that information on hand. :)
    Walter
     
  10. CHG-ON

    CHG-ON Still in love after all these miles

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    I have actually seen my car, on several occasions, lose "sight" of the car in front of me for perhaps 2-3-4 sec.s around a wide bend, maintain speed and not lose tracking the car, which I found to be amazing. I also have seen many times, that the car in front of me will change lanes as another is moving into that spot, going either faster or slower, and the car reacts immediately, tracking the new car. It's pretty impressive. I can't speak to whether it would come to a full stop in emergency, but I did have somebody slam their brakes on and my car reacted immediately. Very gut wrenching, but it worked flawlessly.

    Pretty cool.

    The only issue that I have had, which has been repeated, is when I am on a fairly wide rural road and the guy in front of me is turning in a right turn lane onto another street. The car stays tracked and hits the brakes rather hard. Not good. I have learned to predict this and keep my foot on the accell, so that I can override the braking. Last point, I REALLY like how I can rest my foot on the accel while in cruise, not affecting anything, so that feet are in the correct position in case fast reaction is needed.

    For their first implementation...pretty darn good. Can't wait for More!

    Oh, and last thought. I really would love to see how they "see" the cars around us. I assume it is a mix of radar, camera and soon-to-be sonar (or ultrasound).
     

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