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TACC Tuning?

Discussion in 'Model S: User Interface' started by Saghost, Jan 22, 2015.

  1. Saghost

    Saghost Active Member

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    Those of you who've been using TACC these last couple weeks: Do you have a feel for how precisely it mimics the acceleration/deceleration of the car in front of you? Does it vary when set to different distances?

    Something today got me thinking about the post I saw the other day where they saw higher energy usage driving with TACC - they thought because it was matching the hard acceleration and late hard braking of typical drivers - and Tesla's programming options here.

    With the sophisticated sensor suite they have and the Model S being what it is, Tesla certainly could program a "hard ride" version - set a given distance or time behind and keep to it rigidly, matching every move precisely.

    Or they could program something in the same spirit as the "eco cruise" Ford introduced with the C-Max, which allows the speed to vary some in the interests of efficiency - use the following distance to reduce the braking rate and accelerate slower for better efficiency.

    Initially I was thinking that letting the driver choose would mean some sort of setting in the background, but on reflection this could be made a part of the following distance choice I think...

    As far as I can tell, the only reasons someone would choose short distances are to enable themselves to switch lanes or block other people from cutting in front - both signs that you'd rather go fast and match the preceding car exactly, so on 1 you'd program a hard ride.

    By contrast, the main reason someone would choose the longest distance would be to get a more relaxed drive - at least from the standpoint of more time to react. Having the car use the reaction time to reduce braking events and not use much power to accelerate contributes to the relaxed drive as well as being more efficient, so I think it'd make great sense to have 7 be an "eco cruise" setting.

    Presumably you'd blend the two tendencies in the middle settings.

    Hence the question: Is Tesla already doing this? If not, do you agree with me that they should?
    Walter
     
  2. DPDsModelS

    DPDsModelS Member

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    No I don't think they are doing this but I agree that they should.
    I have noticed how abruptly the car stops when using TACC and then quickly accelerates when traffic starts moving. Many times, I see the brake lights on the cars ahead of me but my MS is still accelerating, leaving me a bit unnerved. I don't know if it is technically feasible but it would be great if the camera mounted in the rear view could pick up the brake lights ahead and stop the MS from accelerating before the sonar picks up the shortened distance. This could make the stops less abrupt, lead to less brake wear and more regeneration of power.
     
  3. Saghost

    Saghost Active Member

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    It's certainly doable - the Auto-Highbeam feature is using the camera to pick out tail lights several hundred yards up to know when to dim the beam (at night.) Distinguishing between tail and brake lights shouldn't be too hard, since all cars have a center brake light but none have a center tail light (though there are a few with full width tail lighting...)

    However, the car should be responding based on the input from the radar which can see hundreds of yards itself. I'm not sure there's much value in doing the camera programming instead of adjusting the response to what the radar can already see. Also, I believe Tesla is buying the camera package and some or all of its functions from Mobileye? If that's the case, they may not be able to get the programming changed easily.
    Walter
     
  4. Dborn

    Dborn Confirmed

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    My understanding is that Mobileye works with its OEM customers and solutions are customised. Only the aftermarket versions do what Mobileye says.
     
  5. Coiled

    Coiled Member

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    Absolutely, it should be done. I believe it can be done with radar only, and I'm sure something like it will be done eventually.

    What you're talking about is a complex map of acceleration/braking versus a set of variables like the distance to the car in front, your speed relative to car in front, selected follow distance and current speed vs. set cruise speed. It sounds like TACC currently uses a somewhat simplified map where it's accelerating pretty hard, braking pretty hard or maintaining speed. Someone said that TACC's applied braking force steps up in detectable increments. The fact that the braking function has steps in it instead of being a smooth curve shows how crude the current map is.

    Right now, the follow distance you set is taken into account only as it relates to one of the variables (distance to car in front). What you want is for the follow distance to effectively transform large portions of the acceleration map, adding another dimension to an already complicated multi-dimensional function.

    This is the kind of thing that will probably be refined and get a whole lot better over a long period of time. If Tesla is willing to put enough work into it, that is. As someone who will be using autopilot a lot, I sure hope they make the effort.
     
  6. Andyw2100

    Andyw2100 Well-Known Member

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    This is what I've written about a few times, including the first day any of us used TACC. I definitely don't think Tesla is doing anything with respect to energy efficiency in TACC yet, and definitely think they should. I'm not sure, though, that I agree that it should just be tied to the distance following setting. I like that being kept independent. I'd like to see Tesla add a separate TACC energy efficiency mode and a TACC proximity mode. The latter would probably wind up being pretty much exactly what we have now. The former would just be a much more mellow version of what we have now, where the car brakes sooner, and accelerates much more slowly, and is much more willing to let the target car "get away."
     
  7. Coiled

    Coiled Member

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    To each his own, but why would you want to have a long follow distance that is maintained precisely with heavy acceleration and braking? Or the opposite? It seems natural that aggressiveness and follow distance would go together.
     
  8. Zythryn

    Zythryn MS 70D, MX 90D

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    I'm curious, what distance setting were you on? Do you get a different reaction from different distance settings?

    I have only experienced it in a couple test drives, however, it seemed very smooth to me. Not abrupt at all unless someone cuts into my lane at a very short distance.
     
  9. Andyw2100

    Andyw2100 Well-Known Member

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    #9 Andyw2100, Jan 23, 2015
    Last edited: Jan 23, 2015
    On the highway, the long follow distance doesn't seem that long at all. And when using the TACC on a rural two-lane, 50 mph road (one-lane in each direction), where traffic often slows down and sometimes even has to stop for traffic lights, etc., the following distance becomes somewhat irrelevant, as your car will get quite close to the target car. (I currently won't use the TACC in these driving conditions because of how it drives.) It just seems simpler to let the distance be controlled the way it is now, and to add the efficiency maximizing mode. People will have to understand that in energy maximizing mode, they are even more likely to lose a target car if they choose a following distance of 1 as opposed to 7, but that should be pretty obvious from the description of what the mode will do.

    Doing it this way should also be easier for people to understand. It's similar to putting the car into range mode. In fact it could conceivably even be an optional automatic toggle with range mode, so that if someone has range mode on they also have the energy efficiency TACC on, but that should be optional. We shouldn't be forced to use the energy efficient TACC with range mode if we don't want to.
     
  10. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    If the forward looking Radar that is tracking the vehicle in front is a Doppler Radar then the algorithm could use the Doppler info as a direct measurement of relative speed (closing speed), in addition to distance, to greatly improve performance and increase efficiency.
     
  11. Saghost

    Saghost Active Member

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    Either they are using a Doppler radar, or else they are achieving Doppler type results by object tracking.

    I say this because the folks reporting back have said that it doesn't pick up a car the was stopped at the light in front of them, but does pick one up that was moving slowly.

    My interpretation of those reports on the TACC thread is that Tesla is using the object's speed to separate the car's from background clutter.

    Obviously as Autopilot develops Tesla will have to address stopped cars, as well as a myriad of other things that might be in your lane - possibly relying more on the camera than the radar.
    Walter
     
  12. tezzla

    tezzla Member

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    Let's not forget; this is version 1.0

    A great start, I'm sure there'll be plenty of minor updates for months/years.
     
  13. DPDsModelS

    DPDsModelS Member

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    I have been using it daily in my commute (which is 120 miles round trip) in all types of situations. I have used all settings from 1 to 7 and have pretty much the same experience. The only real difference is that the car waits a little longer in 7 before starting to accelerate and starts braking earlier as well.

    I do realize that this is version 1.0 and expect some improvement over time. Of course, as we all know that is a great advantage in owning a Tesla in that we can expect an improvement. With my last Mercedes, if I didn't like the ACC that was it - i just had to take it or leave it!
     
  14. Haggy

    Haggy Member

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    It would be nice to be able to set the level of aggressiveness. With other cars, they do pretty much the same thing when it comes to keeping a fixed sized gap. But they don't do everything possible to close up the gap as fast as they can when a car in front changes lanes. They also don't try to shoot up to speed so quickly when there's nothing in front, nor do they accelerate when the cars in front are slowing down just because the distance is set to something closer. If traffic ahead is slowing down, a speed that's moderately higher will close the gap and smoothly transition to the speed of the cars in front without increasing the chances that you will be rear ended.
     
  15. meltoots

    meltoots Member

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    Good post. First, I do want to acknowledge that TACC on my new P85D is version 1.0 of it, and I hope Telsa is reading our posts. And I love my MS.
    I also agree that the TACC is too aggressive when I have it set to 5 thru 7 on the TACC dial. When a car clears my lane and
    it was going slow (like exiting freeway), my MS feels like a launch to get back up to my cruise setting. I also would prefer an
    eco-cruise on the high end of the dial. So my car gently slows as traffic slows and gently speeds up as it clears. Its too sharp now.
    I also would like the ability to cruise without TACC on the dial. So instead of 7 settings, its 6 with the 7th being cruise no TACC.
    So if the weather is iffy for TACC or their are turns or just feel that TACC may be stressed, I could cruise old school style, right
    from the stalk. 1 thru 6, and "TACC Off".
     
  16. Saghost

    Saghost Active Member

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    I can't make any promises about this thread, but Tesla people certainly do read the forum as a whole.

    I really doubt your conventional cruise control setting will ever happen, because of the potential for confusion leading to accidents.

    Maybe if they include an explicit prompt every time you engage the non-TACC cruise, telling you the car isn't keeping track of distance - or maybe after they include automatic braking for impending collisions.
    Walter
     
  17. TTT

    TTT Member

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    I noticed this as well the last few days while driving with TACC, I'm also concerbed if it will stop with the traffic ahead. Has anyone left TACC while exiting the freeway? Did TACC stop the car?
     
  18. Todd Burch

    Todd Burch Electron Pilot

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    TACC behaves off the highway just as it does on the highway.

    Here are some things Tesla needs to tune with the TACC to make it a better experience:

    1. Allow following spacing to adjust more smoothly. This means less aggressive enforcement of the set following distance.

    Currently, the car tries too hard to maintain the set distance, leading to overly-aggressive acceleration and braking. A good example is when I'm set to 70mph (and travelling at 70mph) and there is a car ahead in the distance going 60mph. The radar starts tracking the car very early...as witnesed by the icon on the dash. So it should be able to identify that I'm going 10 mph faster, and identify this over a hundred feet before I get to the car.

    Right now, the car goes 70mph until it gets real close, then uses regen (and sometimes even braking) to slow down when the set following distance is approached. Aside from being unnerving, it's dangerous to unnecessarily use braking (regen or conventional) on the highway. Plus, it's a waste of energy, and it makes you look a bit stupid amongst other traffic.

    What needs to happen is that the car identifies the difference in speeds earlier, and allows enough time to begin perfectly coasting such that when the leading car's speed is matched, the desired following distance is reached. This means more efficiency (coasting), less unnerving behavior, and reduced unsafe slowing on the highway.

    2. When starting from a stop, the car is a bit too timid to accelerate.

    For example, when at a stoplight (or in highway traffic), when the light turns green (or traffic starts moving again) it needs to get on it a little more, and a little more aggressively. Currently, the space between my car and the car in front opens up too much, and I have to help it along with the accelerator.

    However, when in stop and go traffic, other drivers tend to accelerate and brake frequently. So, using (1) supplemented by the camera view (if possible, to identify brake lights ahead) should help with this. That is, if the leading car begins to decelerate, identify it sooner and immediately drop down to coasting or regen as needed--but do it more smoothly, allowing the following distance to close slightly to keep things smooth.

    3. It needs better identification of cars in an adjacent lane. If the car in front of me pulls into a turn lane to the right of me, and slows down to turn, my car (now with no car in front of me) begins to brake aggressively. I can anticipate this now and supplement it with some accelerator input, but the identification for "this car is no longer in my lane) needs to occur sooner.

    4. Crossing traffic ahead needs to be ruled out as a possible collision target more quickly. If I'm traveling along with no traffic ahead of me, and a car far ahead pulls across the road (perhaps coming out from an intersecting road) to turn inthe direction opposite to my direction of travel, sometimes the car identifies this as a collision target as begins braking somewhat aggressively. The car needs to see that the moving target is clearly crossing the lane and filter it out--at least more effectively than it is doing now.

    5. The "accelerate on left turn signal" is a neat and useful feature...but if the lane to my left has a car slightly ahead, the car accelerates and then immediately starts braking once it sees the car ahead in the new lane. I'm not sure the field of view of the radar, but hopefully they can identify when there is a car in the nearby left lane and avoid accelerating in this case (unless that car is going faster than mine).

    6. The car gets confused in tunnels and disables. Not sure if it's technically possible, but it would be nice to fix this behavior.

    One thing I do notice is that my 2006 Avalon with ACC gets confused and disables when heading into bright sunlight (sun low on horizon), but I haven't seen the Tesla do this yet. At least in my experience so far, it seems to handle this situation just fine.

    These are the ones I can think of for now. Tesla, please heed these comments and try to improve these behaviors :).
     
  19. Andyw2100

    Andyw2100 Well-Known Member

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    This was the best, most comprehensive post on the subject I've seen yet! Thanks for taking the time to write it all up.

    All I have to add is that I'd also like to see Tesla, at some point, add an "Efficiency Mode" option to TACC, in which the car would always choose efficiency and smooth driving over staying close to the target car. So you'd have less variation in speed, smoother accelerations and decelerations, and you'd lose the target car more frequently, all in exchange for saving power.
     
  20. Todd Burch

    Todd Burch Electron Pilot

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    I agree, although in the interest of UI simplicity, I believe this goal can be achieved without requiring a separate mode. Implementing the items above should go a long way toward this. Everything can be summarized in one statement: sacrifice "perfect following distance" for smoothness of acceleration and braking, and everything will be nicer.
     

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