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Thread: Accelerometer Noise

  1. #1
    Hi all,

    I'm using lateral and longitudinal accelerometers on last year's car in testing and running into noise issues - the engine increases the noise magnitude by a facter of around 10.

    In addition to bandlimiting the signal, I'd like to try and reduce it mechanically. Has anyone here had success in mounting an accelerometer such that engine noise is reduced, and how was it done?

    I have been experimenting with different mounting places/materials/methods, but some guidance would be really helpful.

    Cheers,

    Dan

  2. #2
    Hi all,

    I'm using lateral and longitudinal accelerometers on last year's car in testing and running into noise issues - the engine increases the noise magnitude by a facter of around 10.

    In addition to bandlimiting the signal, I'd like to try and reduce it mechanically. Has anyone here had success in mounting an accelerometer such that engine noise is reduced, and how was it done?

    I have been experimenting with different mounting places/materials/methods, but some guidance would be really helpful.

    Cheers,

    Dan

  3. #3
    How do you have your accelerometer mounted?

    Straight from MoTeC:
    The best method is to locate the center of gravity of the vehicle and mount the sensor near or on top of it if possible. The best method of attachment is usually 2 sided tape or Velcro.

    I have always used velcro, and we have no issues with noise. Depending on your datalogger's capabilities, you could try applying a filter to the channel to try and clean up the signal.

    One last thing I can think of (not sure if it could really cause this or not) is a poor 0v (ground). Motorcycle charging systems are pretty "noisy".

  4. #4
    Senior Member
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    velcro has always worked for me.

    What is the logging rate you're using? And where did you get the sensor from?
    "Man, I need to practice more!" - Kenny Wallace
    "Try not to have a good time... this is supposed to be educational." - Charles M Schulz
    -OptimumG 2005-2006
    -Turner Motorsports 2008-2009
    -Black Swan Racing 2010 & 2011 Team and Driver's Champions
    -HPD Race Engineer 2011-2014
    -Currently Freelance Data/Race Engineer

  5. #5
    Velcro mounting is a must.
    Michigan State University Driveline Since 2005

  6. #6
    Our data acq with the 2-axis on board accelerometer is rubber grommet mounted for isolation.

    If you happen to be running externals, or something from freescale, try choosing a 0~2g range with the lowest roll-off freq.
    U. of Waterloo 07 Techincal Director
    HPD - Electrical LMP2

  7. #7
    I'm using two sensors - an ADXL203 (2-axis, +/-5g, 0-5V) and a MicroStrain 3DM-GX1 (Relatively slow but compensated accelerometer/gyrometer/magnetometer with wicked orientation algorithm). I will have to try mounting on velcro - thanks for the suggestion.

    I checked my grounds many times and I'm running a seperate battery for the logging equipment, but you can never check grounds too many times.

    Thanks for the replies guys!

    Dan

  8. #8
    Run it through an FFT and then apply an appropriate digital filter.
    Buckingham

  9. #9
    The battery for your data acquisition system may be causing some of your problems as well. We ran into an issue with our engine dyno data acquisition system because we were running the NI PXI chassis on an external power supply and the engine on its own battery. One of the sensors was grounding out through its own casing (which is normally not a problem with a common ground system) and interfacing with the engine power supply and created a nice little pathway for a huge amount of noise to be transfered from the ignition system.
    Engineers aren't boring people, we just get excited about boring things.

  10. #10
    Why are you running your DAQ through its own battery?

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