Field Test of the Toyota Pre-collision System /PCS

Discussion in 'Gen 3 Prius Technical Discussion' started by kenmce, Aug 29, 2019.

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  1. kenmce

    kenmce High Voltage Member

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    From 2012 manual:

    2-4. Using other driving systems When driving PCS (Pre-Collision System)
    ■
    : If equipped When the radar sensor detects possibility of a frontal collision, the pre-collision systems such as the brakes and seat belts are automatically engaged to lessen impact as well as vehicle damage.
    ■
    Pre-collision seat belts
    (front seat belts only) If the pre-collision sensor detects that a collision is unavoidable, the pre-collision system will retract the seat belt before the collision occurs...
    ■
    Pre-collision braking
    When there is a high possibility of a frontal collision, the system warns the driver using a warning light, warning display and buzzer. If the system determines that a collision is unavoidable, the brakes are automatically applied to reduce the collision speed. Pre-collision braking can be disabled using the pre-collision braking off switch

    *************************************

    So, I have all these spiffy Toyota safety systems, paid for them, but never really used them. Decided to change that. Took some boxes and taped aluminum foil to them so the radar could see them clearly, about two square feet / .18 square meters, went down to the park. Found a nice straight road nobody was using. Piled up boxes in the middle of the lane to about the height of a child, (about 3FT. /1M.) made sure the foil was lined up properly, and went back to the end of the road. Put the car in manual drive, got up to about 30 MPH / 48 KPH and drove straight for the boxes.

    ¡BOOM!¡BANG!¡WHAM! the car beeped frantically maybe a second before impact and drove right through them. Cardboard scattered for thirty feet up and down the road. Decided that maybe the Dynamic Radar Cruise Control would have handled it differently, since it is kind of driving the car anyhow. Stacked the boxes back up, went back to the end of the road.

    ¡BOOM!¡BANG!¡WHAM! Not even a beep this time, cardboard spun twenty feet in the air, blasted foil clean off the boxes. At this point I decided it would be really hard to explain what I was doing to the satisfaction of passing officers, (This being NY it is bound to be illegal somehow,) picked up everything and headed out.

    I am disappoint Toyota, disappoint!



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    #1 kenmce, Aug 29, 2019
  2. fuzzy1

    fuzzy1 Senior Member

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    I hope NOBODY here is relying on this for primary collision prevention. It was never intended as such. It is merely a driver assist, a secondary system, meant to reduce (but not anywhere good enough to eliminate) collisions or [update: OM doesn't advertise avoidance at all] collision severity against other cars.

    And in a 2012 car, it is at least 8 years behind the current technology, in an era where the technology is advancing very rapidly but no one is yet offering a consumer system reliable enough to be a primary. Judging such an old system against today's standards is absurd.

    From my 2012 Owners Manual (non-Plug-in)

    upload_2019-8-29_19-32-12.png
    upload_2019-8-29_19-33-9.png
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    #2 fuzzy1, Aug 29, 2019
    Last edited: Aug 30, 2019
  3. Robert Holt

    Robert Holt Senior Member

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    Personally, I like an empiricist, especially one willing to risk his car and an irate policeman to get actual data.
     
    #3 Robert Holt, Aug 30, 2019
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  4. 4est

    4est Active Member

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    The boxes should have been round shape so the radar can reflect back

    Also the radar signature might not match an actual car
     
    #4 4est, Aug 30, 2019
  5. mistermojorizin

    mistermojorizin Active Member

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    Mine's come on one time. Car cut me off and braked in front of me. I came off the gas, and before I hit the brake, the brake sign came on and the brake engaged. I've had other times the "brake" sign came on, but that was the only time it intervened. Now I wonder if you have to be off the gas for it to work.
     
    #5 mistermojorizin, Aug 30, 2019
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Given that one of YouTube videos have been taken down testing the 2010 Prius when it first came out, this is a good refresher.

    It is stated in the excerpt from the manual that you quoted. It’s not designed to stop completely and is only meant to reduce the collision speed:
    Also, at your test speeds, even TSS-P might have a problem. (TSS-P on The Gen 4 Prius can come to a complete stop up to 40km/h for vehicles and 30km/h for pedestrians. Above that, it’ll reduce the impact speed).
     
    #6 Tideland Prius, Aug 30, 2019
  7. 4est

    4est Active Member

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    I have a plug in and the children in the back once reported the seat belt getting tighter as the brake warning came on.
    As opposed to only the front being active
     
    #7 4est, Aug 31, 2019
  8. Grit

    Grit Senior Member

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    There are some people who would come here time to time to post that theirs failed to stop or even warned to stop, and rear ended another car.
     
    #8 Grit, Aug 31, 2019
  9. Tideland Prius

    Tideland Prius Moderator of the North
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    Might be regional differences. I don't think US models have that (just the standard ALRs... not the PCS-Seatbelts)

    ALR - Automatic Locking Retractor
     
    #9 Tideland Prius, Sep 1, 2019
  10. fuzzy1

    fuzzy1 Senior Member

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    Are the PCS seatbelt pretentioners pyrotechnic single-use devices, or are they electric for repeated use?
     
    #10 fuzzy1, Sep 1, 2019
  11. Elektroingenieur

    Elektroingenieur Senior Member

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    The pre-collision system (pre-crash safety system, outside the U.S.) can activate electric seat belt motors, if equipped. There are also pyrotechnic seat belt pretensioners in the supplemental restraint system, which are fired only in an actual collision.
     
    #11 Elektroingenieur, Sep 1, 2019
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  12. Tha_Ape

    Tha_Ape Active Member

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    They're electric... had mine go off about 5 times since I've had the car (7yrs). They'll really pull you into the seat!

    First time it happened my wife and I were going about 70mph in rather heavy traffic, someone cut RIGHT in front of us... not a mild cut off, a pretty severe one. The seatbelts pulled us into the seats and the car started making all types of warnings. I dont remember if it put the brakes on because I did that myself anyway.

    Another time I was driving in a neighborhood and someone ran a stop sign without looking both ways. The car auto braked, reeled me in, and beeped a lot.

    There is a physical switch near the OBDII port where you can disable auto-braking if you want full control of the car, but I leave it on until I have reason to disable it.

    My only guess as to why it didnt work in this test is the radar cross-section is too small. It needs to be a car size object, or at least a foot wider.

    One other time a car in front of me slammed on its brakes on the highway. The prius responded with putting on its brakes and beeping (did not reel me in that time because a collision wasnt imminent, just likely.
     
    #12 Tha_Ape, Sep 9, 2019
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