Fun test of Prius 5 with "paper wall"

Discussion in 'Gen 3 Prius Main Forum' started by georgekessel, May 1, 2010.

  1. georgekessel

    georgekessel Member

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    I was telling my wife that we should get a large roll of thin paper and put it across a quiet road to simulate a "wall". Then I would drive the Prius 5 towards the "wall" at 35mph and see if the collision avoidance system would slam the brakes and stop me before hitting the paper.

    She says I run the risk of the airbags pre-deploying (and says I'm nuts to even think of this stuff).

    Thought I would put it to the board. Note that it's very (VERY) unlikely I would actually try this stunt, but I wonder what would happen if someone did.

    I apologize if this has already been discussed, I was unable to find it in my search.
     
  2. tumbleweed

    tumbleweed Senior Member

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    Good idea but you might have to soak the paper in water, I'm not sure the radar would see the paper otherwise. I wouldn't think the air bags would go off, they deploy when the G forces exceed some amount. There is an accelerometer somewhere, maybe under the passenger's seat?

    Bob Wilson (I think) mentioned some time ago that someone with a PriusV should try setting up a fake person made of water soaked cardboard, or a water soaked blanket over a cardboard frame, or something similar and see what would happen when they tried to run into it.
     
  3. georgekessel

    georgekessel Member

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    Why would the paper need to be soaked in water? What if we used a thicker paper like wall paper?

    Cardboard I'd be concerned of some paint damage at 35mph.
     
  4. tumbleweed

    tumbleweed Senior Member

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    You could try plain dry paper and it might work fine, it's just that RF energy from the radar might not reflect enough from dry paper or cardboard but it should reflect off of water nicely. Also water soaked cardboard or blanket might simulate a person since we're mostly water anyway. You could tape some aluminum foil pieces to the paper and it should reflect as well as a vehicle.

    Paint damage would be something to consider.
     
  5. georgekessel

    georgekessel Member

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    Ah - now that's an idea. A fake wall of tin foil. Forget the paper!
     
  6. V8Cobrakid

    V8Cobrakid Green Handyman

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    tin foil.. good idea.. then all you would possibly need is 1 roll.. if it's at emblem height, the car should pick it up as a barrier. there is a video on youtube of a prius getting "cut-off".. the car beeps and jerks the brakes...
     
  7. bwilson4web

    bwilson4web i3 and Prime

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    Sounds like a good plan. The foil can be draped over a line suspended well above the vehicle. Use masking tape and kite string and it should work out fine. Please make a video of the test.

    Don't worry about the air bags since they are deployed upon hitting a substantial object.

    I prefer a weak, salt water solution soaked paper to more accurately stand-in for flesh and blood. I'm not at 'Mythbusters' stage suggesting using a hog carcass as the target. However, the aluminum foil test has merit for testing one limit. Strips of aluminum would be a better target. If it doesn't stop for foil, no need to proceed further.

    Bob Wilson
     
  8. Thai

    Thai Prius Neophyte

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    I am just subscribing so that i can see the result of this test (if it will happen).

    Anxiously awaiting the results.... :)
     
  9. georgekessel

    georgekessel Member

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    Before I spend more time convincing my wife to assist me in this "test", how certain are we that the airbags won't fire.

    I would hope that they are on a separate system - but are we really certain of that?
     
  10. V8Cobrakid

    V8Cobrakid Green Handyman

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    you have to crush panels to have airbags deploy... there are sensors around the car.

    airbags are designed to offset an impact where you might hit panels with your body. there is no way for the system to set them off unless you literally run into something and crush those sensors....

    the pre collision system beeps, and applies brakes.. that's about it...

    [ame=http://www.youtube.com/watch?v=W-pTakVadH4]YouTube - 2010 Toyota Prius: Pre Collision System[/ame]
     
  11. Flaninacupboard

    Flaninacupboard Senior Member

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    the airbags fire after you've started hitting something, they are only effective for a few hundredths of a second. if they predeployed when the car thought you might be about to hit something, they woud have already deflated by the time you hit it.



     
  12. Flaninacupboard

    Flaninacupboard Senior Member

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    I was going to mension pretensioners on the seatbelts, but that video seems to suggest the seatbelts have a reusable pretensioner, so that's ok.
     
  13. 32kcolors

    32kcolors Senior Member

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    I don't think that's necessarily true. My previous car was declared a total loss after the airbags deployed when the underside of the car hit a raised manhole on a street under construction (where some idiot moved the barricade). Absolutely no damage or crushed panel on the nose/underside of car from what I can see.

    It's an interesting test but there are members here who've experienced the PCS in the real world and posted their experience, all without involving hitting something.
     
  14. The Electric Me

    The Electric Me Go Speed Go!

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    In the previous video, The Toyota created informational, it say's that if the PCS detects an unavoidable collision is eminent and no decelleration is detected the system will "apply the brakes to the maxiumun capability of the system". Well I've always been curious as to what that is? My understanding is the system isn't designed nor is it capable of providing a full stop...if you for some reason didn't recognize a hazard that the system did, it would only tighten seatbelts and slow the vehicle...but never provide a complete stop.

    Is this correct?

    If so, I would think given a test with a fake wall, the vehicle would never stop and given there would be no impact deserving of airbag deployment, air bags would never deploy.
     
  15. 32kcolors

    32kcolors Senior Member

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    Correct, unlike the Lexus version, the Prius PCS isn't designed to come to a complete stop.

    As for the impact, it's still possible if the OP drives through the fake wall.
     
  16. Thai

    Thai Prius Neophyte

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    Even so, i am just happy that it at least slows down the car. PCS in other Toyotas and Lexus do not...exception being the LS460 A-PCS. And according to the video above, PCS in the Prius may stop the car on its own.
     
  17. tumbleweed

    tumbleweed Senior Member

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    Here are a few links that talk about airbag deployment sensors, apparently there are several types and combinations of types in use.

    This looks like a pretty good link dated 2008, good section called "How Airbags Work". I think the airbag control unit on the Gen3 Prius is located under the passenger's seat:
    [ame="http://en.wikipedia.org/wiki/Airbag"]Airbag - Wikipedia, the free encyclopedia[/ame]


    This is an old link that is still informative:
    Air Bags: How They Work

    No date on this one but interesting, interesting paragraph on mechanical systems:
    Air Bags and Crash Sensors
     
  18. donee

    donee New Member

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    Hi All,

    While Tumbleweed brings up a good point about paper not reflecting enough RF energy, the water soaking solution would probably not work. At the frequencies that automotive radars operate at, water absorbs the energy. So, soaking the paper in water would make it even more transparent to the radar.

    The solution is simple though. Just glue some squares of tin foil to the paper in the shape of a car.
     
  19. tumbleweed

    tumbleweed Senior Member

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    Foil would certainly reflect the energy. The frequency of this radar is 76.5 GHz, well beyond anything I have worked with so I wasn't sure how it would react. But at that frequency it seems to me that it should detect water. I know when you get much above 8 or 9 GHz rain becomes a significant factor over longer distances, i.e. search radar and microwave radios.
     
  20. Tideland Prius

    Tideland Prius Moderator of the North
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    I'm pretty sure it does the same as the Prius. There's no reason for it not to partially brake (all PCS-equipped cars also come with radar cruise)
     
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