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DRCC emergency stop at 70mph

Discussion in 'Gen 4 Prius Technical Discussion' started by raspy, Jul 26, 2016.

  1. cproaudio

    cproaudio Speedlock Overrider

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    No it doesn't. DRCC only tracks what's in front of you, not the sides or the rear. It only tries to save you from fault. It's not perfect but I would still get it b/c it's better to have it and not need it than need it and not have it. Remember, DRCC also comes with PCS. PCS already saved me from 2 at fault accidents.
     
  2. Blizzard_Persona

    Blizzard_Persona Senior Member

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    What's PCS? Too many acronyms... I know what PCP is never heard of PCS?
     
  3. cproaudio

    cproaudio Speedlock Overrider

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    Pre-Collision System. It's always on and reduces the impact speed if you fail to brake after it warns you of imminent frontal collision.
     
  4. raspy

    raspy Senior Member

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    I don't know about US specs.

    With regard to the DRCC slamming on the brakes, at least with the Prius having rear LED lamps then they would illuminate quicker than if you were driving a vehicle fitted with regular lamps at the rear.
     
  5. wrprice

    wrprice Active Member

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    My use of the word "amazing" isn't in comparison to DRCC equivalents of other manufacturers. I am quite impressed with what Toyota (with all of their lawyers given the litigious US market) has managed to deliver in a mass market vehicle, at this price point, with the functionality and safety value it provides. It does this using one millimeter-wave radar mounted low in the nose, a forward looking single-lens camera, wheel speed sensors, perhaps a steering angle sensor, and software.

    I write software for a living, but nothing with life-safety implications. That, plus the realization of just how limited the external inputs are, is my benchmark.
    There's no meaningful difference in illumination speed compared to human reaction time.
     
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  6. raspy

    raspy Senior Member

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    With regard to your last statement, that's not what research seems to say, LED Stop Lamps Help Reduce the Number and Severity of Automobile Accidents https://chemlinks.beloit.edu/BlueLight/pages/hp/an1155-3.pdf
     
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  7. wrprice

    wrprice Active Member

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    Lamp rise time for LEDs is something like 166ms faster, which is not insignificant, I grant you. However, when it comes to actual crash avoidance the NHTSA doesn't agree, and finds it inconclusive.

    https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/811712
     
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  8. cproaudio

    cproaudio Speedlock Overrider

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    It doesn't matter about LED VS incandescent brake lights as almost all the recently sold cars' center brake lights are LED.
     
  9. wrprice

    wrprice Active Member

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    I'm more interested in the long-term effects of this shift, rather than the probabilities associated with any single (potential) accident event. For instance, I imagine that LEDs are less prone to burning out; or if an element does fail hopefully it doesn't take the entire cluster out. In the end does that mean there will be fewer vehicles with inoperable brake lights? I hope so.

    LEDs or not, the manufacturer can still help or hinder visibility and redundancy. Brake lights should involve more than one element, each, so we're not dependent upon a single LED in each position. The 2004-05 Prius was an example where Toyota "smoked" the plastic around the brake lights to blend with the lower rear hatch window. Did that hinder visibility? They switched to clear plastic for 2006, supposedly due to internal heating in the smoked version causing some plastic to melt (and possibly block light output).
     
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  10. Tideland Prius

    Tideland Prius Moderator of the North
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    Possibly. The van was parked to one side. The radar may or may not pick it up. It's an out-of-the-ordinary situation and one should always assume the vehicle won't respond as expected. It's an assist feature, meant to make life easier.

    Yeah there's a hard curve that I travel occasionally where the highway curves from westbound to northbound and the Gen 3's DRCC will lose lock and if you let it be, it will be a rocky ride around the corner as the car locks and unlocks and accelerates and brakes. Like you, I cancel DRCC for that corner and resume it after it straightens out. I think the Gen 4 will actually cancel DRCC in a corner such as that. (Based on the media demo)

    No. I have suggested that to Toyota before at one of our Prius Expert meetings. They have the equipment (e.g. on the Lexus LS or Toyota Crown with rear facing millimeter wave radar), they just need the software code.

    Besides, you should be paying attention anyway and you would take evasive manoeuvre. It won't slam on the brakes but it will brake hard if necessary. And really, at that point, it's PCS that's taking over not DRCC.

    Depends on the year. Older vehicles (I mean early 2000s to maybe a few years ago) had multi-LED setups for brake lights (both CHMSL and regular brake lights) like the Gen 2 & Gen 3 Prius. As technology improves, fewer physical bulbs are needed to produce the require lux to meet regulations. The Gen 4 now uses just one bright LED for the regular brakelights and one of those is much brighter than the 6 LEDs on the Gen 2. (6 per side). On the older ones, if one blows out, it's not too big of a deal since the rest will still illuminate (they're not wired in series) but of course the light as a whole will be dimmer as each bulb blows out.

    On the Gen 2, it's not smoked plastic. It's just black glossy painted plastic. (Smoked makes it sound like the cover is darkened, which isn't the case. It's a clear plastic housing). I think it was a styling design, meant to visually widen the lower rear glass. It also means each bulb appears larger because it's reflected on a curved surface, thus increasing the surface viewing area of the brakelights. The bulbs themselves are tiny and look like the 2006-2012 RAV4 taillights (which aren't reflected and are directly visible to someone looking at the RAV4).
     
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  11. alanclarkeau

    alanclarkeau Senior Member

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    The manual has a number of scenarios where it will do "odd" things, but when I drive with it I keep a bit of a picture in my mind of where it's likely to be looking - tighter bends, I've taken manually and then handed over, particularly if I'm on 3 bar distance - 1 bar distance is less likely to have that semi scenario.

    Overall, I love having it - it was a YES pre-requisite with whatever car I bought this time. And yes, it's probably phase 2 of what will be an ongoing improvement regime.
     
  12. wrprice

    wrprice Active Member

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    Doesn't line up with my recollection of my '05. It sure seemed like the cover was not clear for the topmost section. But I'll take your word for it, as it's been two years since I last had it. I'll take a closer look the next time I walk past an '04-05.

    Whether the darkened look was because of the surrounding plastic or a darkened/smoked cover would indeed make a difference in how much it interfered with brake light visibility.

    I'm disappointed to learn that we're back down to a single point of failure in the brake lights of Gen4. Here's hoping the MTBF is high enough. With a second element at least there'd still be something, if only 50% of the lumens, if one of the two went out. Lots of drivers around here have failed bulbs in one or two of the three light positions.
     
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  13. cproaudio

    cproaudio Speedlock Overrider

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    1 bar is also the most dangerous setting as OP has proven. I never set my at 1 bar because at 3 bars coming up a slow traffic or a traffic jam, it brakes pretty hard. I'd imagine at 1 bar it'd brake even harder or worst yet, it cancels out and left you with even less safe braking distance.
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
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    I would take a photo but we traded in our Gen 2 six months ago. Here's the largest photo I could find on the internet.

    [​IMG]

    The cover itself is clear. The top part that is housing the LED brakelights is black plastic, giving that dark look. You can see the reflection of the trees and the sky on the taillight that give some indication that it is clear. In addition, if you look at the side of the cover, you can see that the taillight, reverse light and indicator backgrounds are chrome and the brakelights are black, again another indication that it is the background that is coloured black, rather than the cover that is smoked at the top section. Of course if you can see one in real life, then have a look for yourself :)

    The LEDs were not particularly bright back in those days so I don't think any manufacturer will want to do anything that would reduce the brightness of those lights (Again, because LEDs were expensive and they had to put multiple bulbs to get the required brightness).


    More importantly, there needs to be a "Brake Light Bulb" failure light on the dashboard. Like you, I've seen people with only one working brake light (and in one case, no working brake lights. In that case, the taillights were doubled as brakelights so I guess the 2nd filament blew so the owner probably thought - well my taillights are working.... so the brakelights must be ok).

    With some European cars, there is a "nearest bulb" feature where if a critical bulb fails, it'll use the next nearest (and brightness) bulb to temporarily substitute. I've seen an X5 with one of its rear foglights (one of the rare ones that have 2 rear foglights) on as a taillight because the taillight was blown. That and it's also a law in some European countries that you must have all lights in working order and you must carry a spare bulb as part of your emergency kit to replace it if you get pulled over for a blown bulb.
     
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  15. raspy

    raspy Senior Member

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    Has anyone else seen the last minute of this video from EURO NCAP? Apparently, in April 2016, the Prius was one of the first new cars where they tested the 'autonomous emergency braking' (their words, not mine)


    Do you think these tests should also include simulating what it would be like if say a 10 year old car was being driven behind the Prius, and whose braking distance might be much more than the Prius, in an emergency?
     
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  16. wrprice

    wrprice Active Member

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    What would that measure? Is the vehicle type, age, speed, following distance, or other-driver behavior in any way under the Prius's control in that situation?

    My perception is that getting rear ended while avoiding an imminent frontal collision is still better than not doing everything possible -- including braking as hard and fast as you can -- to avoid slamming into the front obstacle at a higher speed. The direction of travel is the primary concern. If PCS slams on the brakes then, in many/most cases, the driver already wasn't driving defensively enough. To then be more concerned about whether the driver behind you will be able to stop is to focus on the wrong thing.

    None of the systems prevent swerving to the side to avoid both, if safe to do so.
     
  17. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes, it's been posted before but it's still good for anyone to watch. AEB seems to be a European term.

    Well to be honest, the guy behind you is following too close if he can't brake in time. In addition, in driving school, you were taught to leave even more space in front of you if the person behind is travelling too close. i.e. you're leaving enough space for the both of you, rather than just yourself.
     
  18. alanclarkeau

    alanclarkeau Senior Member

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    No - it would be impossible to cover every permutation of that scenario - as others have said, the person behind you needs to be more careful. Mine slowed down (under DRCC) a bit abruptly the other day, I had a glance at the car behind which I knew was a bit too close - he kept a good distance after that.

    There are more and more cars on the road with both AEB as well as DRCC - I had a VW Golf I was following the other day which had DRCC, and someone slipped in front of him into the gap, the Golf slowed quite abruptly, as did Samantha - until I overtook them, that's when I noticed his RADAR thingy in his grille.
     
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  19. KimPrius3

    KimPrius3 Member

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    I was astounded at the utter ignorance of the sales people at the dealerships I visited. 2 out of 3 dealerships were so uninformed/educated about the Gen 4 that I had one salesman tell me the advanced tech package only came on the Prius V. I suggested to one guy that he join the Priuschat forum so he could learn about the Prius. I read nearly 200 pages of the Owner's Manual that I downloaded, watched a few videos and joined Priuschat of course. I ended up buying from a lady who had owned every Prius since Gen 1 and had her own Gen 4. She really knew her stuff.
     
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  20. alanclarkeau

    alanclarkeau Senior Member

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    I encountered so many ignorant (to Prius) salesmen - about 10 across 6 dealerships (I didn't encounter any ladies in TOYOTA dealerships, only Volvo and Mazda).

    When my local dealership had a Prius in stock, I rang and said to the receptionist "Do you have a salesman who KNOWS Prius? If so, put me through to him - and if he turns out to know nothing like the other 10 salesmen I've spoken to, I'll be walking straight out". She said, just wait for a moment and I'll be back - and put me onto a salesman who had been a TOYOTA mechanic for quite a few years and gone into sales after damaging his wrist - he knew Prius well. The car had arrived on the Friday (their first), and I drove it on the Monday, and he'd obviously researched it, as he knew the buttons, setup, the improvements over the old model etc well. I bought it.