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Detect A Road Bump — Parallax Forums

Detect A Road Bump

jordan89jordan89 Posts: 6
edited 2011-11-22 20:22 in Accessories
Dear All,
i need to connect sensor to Arduino UNO to detect a road bump while the car pass fast through it ... can i use the piezo film sensor or i need an accelerometer like "ADXL193" to detect the shock ?
any body know any other sensor it can solve this problem

Regards

Comments

  • PublisonPublison Posts: 12,366
    edited 2011-11-19 09:34
    An accelerometer would probably work best. Like the Parallax product :

    http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/accelerometer/List/0/SortField/4/ProductID/585/Default.aspx

    Y    ou would have to read the G force and adjust the output for your "bump"

    Can't help with Arduino code, but there is BS2 and Propeller code on the linked product page.
  • jordan89jordan89 Posts: 6
    edited 2011-11-19 14:48
    Thank you Publison for your reply , i will check that
    i have another question : i have memsic 2125 accelerometer http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/93/Default.aspx?txtSearch=memsic+2125 please can i use this accelerometer to detect a bump , check its datasheet .... i tried it a lot but its not work i think its measure only tilting .. if you have any idea about memsic 2125 please tell me ... i need a solution as soon as possible

    Regards
  • FranklinFranklin Posts: 4,747
    edited 2011-11-19 15:01
    The memsic 2125 will show the bump but you need to write code to filter out the signals you don't want. Accelerometers are designed to measure acceleration but can't destinguish from acceleration and gravity, that's your job. Good luck with your project.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-11-19 15:03
    The Memsic 2125 is a two-axis accelerometer. It measures acceleration in the X and Y axes, but not Z. However, you can still monitor vertical acceleration by mounting it on its side.

    -Phil
  • jordan89jordan89 Posts: 6
    edited 2011-11-19 15:17
    Thank you Franklin, yes the memsic will show the bump if you drive in a specific angle like straight road , i tried it but if you drive up or down through road with different angle it will not work ... i think iits hard to detect a bump using tilting , i think the best solution is to use an accelerometer with shock sensing property , i think i need the (Z axis measuring) , Am i right ?

    not all accelerometer designed to to do the same work, some for tilting , some for rotation and some for shock sensing or all of them check this http://www.analog.com/en/mems-sensors/inertial-sensors/products/cross-reference-guides/cross_ref_Mems_sensing_applications/resources/fca.html

    if you have any other ideas or code concerning the memsic 2125 i'll be thankful

    Regards
  • jordan89jordan89 Posts: 6
    edited 2011-11-19 15:28
    Dear Phil,
    i think memsic 2125 is designed to measure ONLY tilting not acceleration/transitional , please can you check its datasheet and answer me, its critical i need a solution as soon as possible

    i have another solution from Analog Devices Company its "ADXL193" its specific for shock sensing, its measure up to -+250g , do i need that big amount of g ?

    Regards
  • PublisonPublison Posts: 12,366
    edited 2011-11-19 15:37
    jordan89 wrote: »
    Thank you Publison for your reply , i will check that
    i have another question : i have memsic 2125 accelerometer http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/93/Default.aspx?txtSearch=memsic+2125 please can i use this accelerometer to detect a bump , check its datasheet .... i tried it a lot but its not work i think its measure only tilting .. if you have any idea about memsic 2125 please tell me ... i need a solution as soon as possible

    Regards
    As Phil pointed out, the 2125 is a two axis chip and you could mount it 90 degree off it's normal configuration to achieve a z-axis sensor. Turn it up on end and use the x or y as your z.

    The sensor I linked to is a 3-axis and will do z-sensor with the module mounted on plan.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-11-19 15:51
    The MXD2125G chip measures acceleration along the X and Y axes up to +/-3 g. That's how it measures tilt. If you tilt it such that one of the axes is vertical, it will measure vertical acceleration. Since the baseline (i.e. offset) at that angle will be 1g, it should be able to handle a range of -4 to +2 g relative to that offset. That may or may not be enough for the kind of bumps you expect to encounter, though. My only advice would be to try it and see, since you already have one.

    BTW, if you had two of them, you could extend the acceleration range by tilting two of them slightly, but at opposite angles.

    -Phil
  • jordan89jordan89 Posts: 6
    edited 2011-11-19 16:00
    Thanks Phil i'll try it and tell you the results :D .... do you know which code is work with this case ?
  • ercoerco Posts: 20,256
    edited 2011-11-20 17:58
    You DID mount the accelerometer on your A-arm near the wheel, not inside the car...?

    Like real estate: location, location, location. Your shocks are designed to do a marvelous job of filtering out road bumps. You could almost use a simple rotary potentiometer and sample it fast to see when & how far your A-arm rotates. Or a linear potentiometer parallel to your shock/strut. Many ways to get to Carnegie Hall besides practice.
  • MikeKMikeK Posts: 118
    edited 2011-11-20 19:00
    Vibra Tab with a small mass attached? (tongue in cheek: A full glass of water sitting on a plate with a moisture sensor. Bump spills some water. Moisture detector senses water, and hence bump. It requires larger and larger bumps to trigger as time passes, unless you have an assistant to refill the glass).

    Edit: Oops, it would only detect one bump, unless there were some way to dry the sensor.
  • kwinnkwinn Posts: 8,697
    edited 2011-11-21 21:53
    erco wrote: »
    You DID mount the accelerometer on your A-arm near the wheel, not inside the car...?

    Like real estate: location, location, location. Your shocks are designed to do a marvelous job of filtering out road bumps. You could almost use a simple rotary potentiometer and sample it fast to see when & how far your A-arm rotates. Or a linear potentiometer parallel to your shock/strut. Many ways to get to Carnegie Hall besides practice.

    Erco has some pretty good suggestions if the aim is to measure the severity of the bumps. On the other hand if you are trying to measure how well the vehicle suspension deals with the bumps you may want to place the accelerometers in the cabin. In both cases you should be able to separate the effects of tilt/gravity from bumps by the rate at which the signal changes.
  • jordan89jordan89 Posts: 6
    edited 2011-11-22 12:34
    kwinn wrote: »
    Erco has some pretty good suggestions if the aim is to measure the severity of the bumps. On the other hand if you are trying to measure how well the vehicle suspension deals with the bumps you may want to place the accelerometers in the cabin. In both cases you should be able to separate the effects of tilt/gravity from bumps by the rate at which the signal changes.


    Kwinn i need to detect the bump severity should i put the sensor outside the cabin ??
  • sidecar-racersidecar-racer Posts: 82
    edited 2011-11-22 12:42
    Another possibility is a linear pot that links from wheel(?) to chassis. This gives voltage to distance. A/D from there, do what you need with computer. We use that on our racer for tuning shock settings. We were sampling 100 times per second.
  • ercoerco Posts: 20,256
    edited 2011-11-22 15:08
    jordan89 wrote: »
    Kwinn i need to detect the bump severity should i put the sensor outside the cabin ??

    ***Sigh***
  • PublisonPublison Posts: 12,366
    edited 2011-11-22 15:19
    jordan89 wrote: »
    Kwinn i need to detect the bump severity should i put the sensor outside the cabin ??

    Re-read post #11.

    Where do you want to mount the sensor? Do you want real bump or bump felt in the cockpit?

    @erco, I feel your pain.
  • PublisonPublison Posts: 12,366
    edited 2011-11-22 15:38
    @jordan

    Can you describe exactly what you are trying to accomplish? You have been pretty general up to this point.

    The more information that you provide will get you more back. (Of course we can't help with Arduino code, this is a Parallax forum)
  • kwinnkwinn Posts: 8,697
    edited 2011-11-22 20:22
    If you want to get the maximum sensitivity the accelerometer should be mounted on the wheel A arms or the axle as close to the wheels as possible.
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