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How far away can the radar see?

Discussion in 'Model S: Driving Dynamics' started by kirkbauer, Jul 4, 2015.

  1. kirkbauer

    kirkbauer Member

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    I'm very new to the MS and the TACC. I had it set to about 50mph recently and a car ahead was stopped at a red light. The car was happily going 50mph until it was too close for comfort and I had to hit the brakes. Obviously it needs to be improved to start braking earlier (ideally using regenerative braking) but does anybody know how far away it can see? I'm wondering if it even knew that car was up there.
     
  2. Majerus

    Majerus Member

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    Its been mentioned in multiple posts, the car does not pick up stopped objects well when in TACC. The emergency braking may have stopped the car but it would have been a hard stop, not regen for sure. Pay attention and be safe, understanding the limitations of TACC will take some learning on your part its hard to explain what it can and cannot pick up. After driving a few thousand miles its easy to understand situations which it is not suited for.
     
  3. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    #3 andrewket, Jul 4, 2015
    Last edited: Jul 4, 2015
    A few things...

    1/ the radar can pick up cars several hundred feet ahead.
    2/ when TACC is tracking a car, the cruise indicator is blue. When it's not, it's grey.
    3/ you can adjust the following distance with the knob on the end of the cruise stalk.

    4/ If a car is moving in front of you and comes to a stop TACC knows it's a car. If you come around a corner to a stopped car, the car will likely think it's a permanent stationary object. For this reason, TACC is best used on the highway.
     
  4. kirkbauer

    kirkbauer Member

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    All good info, thanks. For the record I was just testing the feature, not relying on it :)
     
  5. kuttakamina

    kuttakamina Member

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    I had this happen to me last night as well. My car sped up towards a stationary car at a red light. I think if you are using tacc inside a city you need to pay full attention to it yourself. Even on the freeway, you need to remain aware if the cars in front if you need to stop immediately like in the case of an accident.
     
  6. martinwinlow

    martinwinlow Member

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    I would be interested to hear comments on why people think the system does not automatically slow the car when approaching an obvious, fixed hazard such as a major junction or roundabout. I suppose it would be fair to make the same comment made earlier i.e. TACC should not be used on any road other than a highway/motorway but, here in the UK, we have major dual carriageways - i.e. 2 or more lanes in each direction - with roundabouts, the A10, A303 and A1 immediately spring to mind.

    The car knows they are coming up from its satnav system. Surely it would be a pretty simple thing to code for? MW
     
  7. pan

    pan Member

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    I've now used ACC (TACC) on three cars, 2010 BMW 650, 2012 BMW 650ix and Tesla P85D. The best and most consistent is the Tesla. I use it in rush hour stop and go, on highways or on roads I need to stay in a reasonable speed range to not get a ticket. The Tesla TACC has better acceleration from a stop than the BMWs, meaning it mimics more closely how I accelerates. In stop and go it does a great job of stopping in plenty of time and when stopped stays active for a longer period of time than the BMWs. The Tesla system has surprised me in most cases it has recognized stopped cars. I never expect that to be 100%. There are just to many variables. The only weakness I've experienced is when changing lanes the TACC starts to accelerate then stops the acceleration too soon as if it wants to go but sees the car in front and slows. This may be a function of the software I'm still running 2.4.236.
     
  8. Saghost

    Saghost Active Member

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    The radar can probably see ~600 feet (but as pointed out by other users, a car that first becomes visible while stopped may well get ignored - relative motion is used as a filter.)

    It's not certain, but available data suggests Tesla may be using the Delphi phased array system - even if they aren't, they likely have something with fairly similar specs. Here's what the Delphi system can do:

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

    It simultaneously scans a narrow arc out to 174m (~600 ft) and the full front quadrant out to 60m (~200 ft) 20 times per second, tracking angle, range, and relative velocity on everything in the field of view (up to 64 objects.)
    Walter
     
  9. Todd Burch

    Todd Burch Electron Pilot

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    Are you aware there's an option on the setting screens to accelerate when a left turn signal is applied? That might be your culprit.
     
  10. MichFin

    MichFin Member

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    I realized after some time you just need to leave the blinker on longer. As soon as the blinker stops so does the acceleration. So if you use the changing lanes blinker (3 blinks) you speed up for a second and that it.
     
  11. Tony Lin

    Tony Lin Member

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    so what is the best way to use TACC under heavy traffic that is moving in 10~20 KM / Hour? thanks
     
  12. martinwinlow

    martinwinlow Member

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    It only works if you are doing at least 30kph. There is an upper limit too, I believe, but I can't find it in the manual. MW
     
  13. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    It's 88 mph. I guess they don't want you timeshiftimg accidentally.
     
  14. CHG-ON

    CHG-ON Still in love after all these miles

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    I have been very happy with TACC. I use it in traffic all the time and have had no problems. I do make sure that I am completely aware of what is going on and will intervene occasionally. One very cool thing that I have found is that while in TACC in traffic and stopped: All cars begin to move forward, going straight. I am turning right at the light. When the other cars move ahead, my car starts to move, but when I turn the wheel, the car does not accelerate quickly as it would if going straight with no cars on front of me. It waits until I have executed the turn before it starts returning to cruise. Clearly it knows steering angle and is compensating for it. It works like a charm. I was quite surprised and impressed when I finally realized what it was doing.

     
  15. sowbug

    sowbug Member

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    Curious if you've seen this.

    I'm in the carpool (leftmost) lane in stop-and-go traffic with TACC set at 7, and all's well. Then a motorcycle toodles along at a much faster speed (probably 20-25 mph), lane-splitting between my lane and the next lane over. TACC locks onto the motorcycle and decides it wants to follow along, so my car speeds up suddenly until it re-locks onto the car right in front of me and then regens back to a safe speed. Nothing bad ends up happening, but it seems like the car is reducing its own options for no good reason.

    (I'm sorry this is a little off-topic. As a new-ish member to the forum, I'm still considered a would-be spammer and thus can't create appropriate new topics on my own.)
     
  16. scottreds2k

    scottreds2k Member

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    I use TACC all the time in traffic and on the open road to help control my "normal" aggressive driving tendencies. It does seem to have the ability to see pretty far and the 600' estimate seems about right. I happened to be following a state police SUV today and as my upper limit of speed (speed limit + 8 mph) was reached and he kept pulling away. The little blue cruise icon with the car didn't change to grey for what was well over 100 yards and definitely closer to 200.

    Traveling in traffic around DC/MD, while never enjoyable, is more tolerable using TACC. I've been able to go ~15 miles without touching the pedals when traveling on Rte 50W /495/ 95N.
     
  17. gordo

    gordo Member

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    Yes! I have this happen all the time commuting along 101 in the Bay Area across several 6.2 releases now. I still see it happen with the latest 2.4.250. For some reason it seems that when given two objects in front of you traveling at different speeds, the AI will briefly lock onto the faster one until the distance between you and the slower one is too close for comfort and it backs off. No idea why it's programmed that way, but I can confirm that it's been doing this for some time.
     

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