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Blind spot warning — Parallax Forums

Blind spot warning

ChetChet Posts: 150
edited 2010-07-19 23:51 in General Discussion
On my wife's Audi A8L, there are substantial blind spots.· I am looking at possibly using regular parking sensors to make a blind spot warning device for the A8 (or any other car for that matter).· The Ping is not weather proof, so that is excluded. I have several sensors from one of the e-bay back-up warning kits that I bought but never installed and would like to put one on each side of the back bumper to act as a blind spot warning when I turn on the directional signal.
I do not have a scope, which makes it difficult to move forward.·Does anyone have experience using these type of ultrasonic transducers?

Thanks in advance for your feedback

Chet

Comments

  • Invent-O-DocInvent-O-Doc Posts: 768
    edited 2010-07-15 13:28
    It is a bigger problem than you think. Units on my Chrysler minivan use two transducers per side at slightly different angles off the side view mirrors. It can be installed as an add-on kit. The engineering challenge isn't the sensors as much as the logic that allows ignores extraneous data such as driving near railings , trees, etc. The add on units i have are good at detecting if someone is in the blind spot or is creeping up from behind but cars that I pass don't show up on the indicator unless they hang out in the blind spot for a long time.

    I think I have seen the bare transducer at sparkfun or futurlec. The data sheet should be on the page for that item. Good luck!

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    Tom Talbot
    New Market, MD, USA
  • ChetChet Posts: 150
    edited 2010-07-15 14:52
    Tom, i intend to only activate detection when I put on my indicator. This should avoid the railing warning etc. What is the add-on kit you are using?
  • ercoerco Posts: 20,260
    edited 2010-07-15 15:42
    You're talking about using a sensor while driving and changing lanes, not just backing up and parking, correct? Ultrasonic sensors are only reliable in calm, still air. Driving even at moderate city speeds would cause erratic operation.

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    ·"If you build it, they will come."
  • Invent-O-DocInvent-O-Doc Posts: 768
    edited 2010-07-15 18:53
    I bought an add on kit from MOPAR

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    Tom Talbot
    New Market, MD, USA
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-07-15 19:15
    I agree with erco - "Ultrasonic sensors are only reliable in calm, still air. Driving even at moderate city speeds would cause erratic operation."

    That said, we have the same sort of sensors (Weatherproof Ultrasonic Sensors) on our Chrysler(2007 Pacifica), but the only time I have heard them go off with a warning was when someone was standing at the back end and the lift gate was about to open or close.

    Inside the car we have a backup camera, which often I have thought would be a good idea to have two additional cameras aimed in the "blind spots" on either side of the vehicle. That way when going forward and engaging a turn signal, the appropriate camera would provide the blind spot video feed to the dash inside the car.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2010-07-15 19:51
    I'll second the camera idea, especially now that they are inexpensive. My neighbor has a rock-crawler Bronco and he asked me about developing a multi camera system for the front lower corners so he could negotiate very tight spots by being able to see what he is doing. I checked into the parts needed for that and came up with about a $130 total cost.

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    Andrew Williams
    WBA Consulting
    PowerTwig Dual Output Power Supply Module
    My Prop projects: Reverse Geo-Cache Box, Custom Metronome, Micro Plunge Logger
  • ChetChet Posts: 150
    edited 2010-07-15 20:26
    Thanks for the feedback. It appears the accoustic/ ultrasonic approach is out. I have started looking at othere possible solutions. One is reflected IR leds and the other is "radar". The latter looks like the most used, but there is not a lot of information out there on DYI radar sensors.

    Andrew, I do have wireless cameras (from the plate mounted back up cameras) that could go that route. The problem is the estetics aspect of having an extra screen planted somewhere. The Audi electronics are pretty extensive so hooking it into the MMI (screen) would be a pretty formidable challange.

    Tom mentioned he retrofitted and add on kit from Mopar. Maybe I can have a look into that.

    Back to the hunt.....

    Chet
  • ercoerco Posts: 20,260
    edited 2010-07-15 20:35
    Possibly·a laser distance measurer could be used... not sure how they work at speed, though.

    These were on sale for $70 a few days back: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390216396478

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    ·"If you build it, they will come."
  • ChetChet Posts: 150
    edited 2010-07-15 22:24
    erco, the laser is good for speed and distance but the beam is to narrow to be practical without mechanically sweeping the beam.
  • ercoerco Posts: 20,260
    edited 2010-07-16 00:08
    OR, sweep the laser beam by coolly and methodically swerving your car side to side in your lane, which also helps to alert other drivers that a lane change is imminent... [noparse]:)[/noparse]

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    ·"If you build it, they will come."
  • K2K2 Posts: 693
    edited 2010-07-16 02:04
    Two worn shocks could provide dither in elevation. Or perhaps the laser itself could be mounted on the end of a droopy coil spring - I believe Dr. Seuss has provided various·illustrations of·the general idea.

    Not as cool as erco's suggestion, but he's just a cool guy!

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    "Let's not bicker and argue about who killed who."

    Post Edited (K2) : 7/16/2010 2:47:20 AM GMT
  • ChetChet Posts: 150
    edited 2010-07-16 02:31
    This is how we do it now here in Houston.· I was trying to find a different approach......yeah.gif
    erco said...
    OR, sweep the laser beam by coolly and methodically swerving your car side to side in your lane, which also helps to alert other drivers that a lane change is imminent... [noparse]:)[/noparse]

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-07-16 04:05
    Place some real BIG curb feelers that extend off the back end of the car up and outward by at least 5 feet smilewinkgrin.gif ... you'd look like a big catfish going down the road in reverse. I guarantee people would keep their distance from you! tongue.gif

    The laser approach, even IR is going to create an interference issue if someone else incorporates the same idea on their vehicle.

    I wonder how differential 'ambient noise' detection would work? Essentially two microphones that 'listen' all the time in close proximity to one another. In a differential configuration either through software or hardware, any common mode noises are rejected so that only the difference in the two mics are looked at. Under 'normal' driving circumstances the ambient noise level from the road would be somewhat predictable, even at different driving speeds ... add another vehicle within earshot of the mics and there should be a detectable shift or difference in what the microphone picks up. This method eliminates any possible interference from other vehicles that might have a similar detection system.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.

    Post Edited (Beau Schwabe (Parallax)) : 7/16/2010 4:11:34 AM GMT
  • yarisboyyarisboy Posts: 245
    edited 2010-07-19 01:59
    I used to work for a company that swept an ultrasonic sensor back and forth to image the prostate. It was in a very undignified orifice while the cancer inspection was being done.

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    cloyd's corollary: Hardware is easy, software is hard.
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-07-19 02:25
    I keep a red metal ladder connected to the top of my truck when I drive around. When I want to change lanes, special actuators slide the ladder to that side of the truck and wiggle it in such a way to make people believe it's about to fall off.

    One flick of a switch and it's amazing how courteous people can get.






    devil.gif
  • soshimososhimo Posts: 215
    edited 2010-07-19 20:53
    ElectricAye said...
    I keep a red metal ladder connected to the top of my truck when I drive around. When I want to change lanes, special actuators slide the ladder to that side of the truck and wiggle it in such a way to make people believe it's about to fall off.

    One flick of a switch and it's amazing how courteous people can get.






    devil.gif

    DoD and military vans have cameras placed on the roof in the back - one on either side. They are inclined to look at the blind spot. Presumably (and if I knew I probably couldn't say anyway) for checking security before entering or exiting the van, but I imagine they can be used just as effectively as blind spot cameras.
  • AJ-9000AJ-9000 Posts: 52
    edited 2010-07-19 23:51
    There are rearview monitors that clip onto the rearview mirror·like this one that uses a standard AV hookup.
    http://www.pyleaudio.com/itemdetail.asp?brand=&cat1=Car%20Security&cat2=Rear%20View%20Camera%20Systems&model=PLCM103
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