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Gyroscope 3-axis accuracy help — Parallax Forums

Gyroscope 3-axis accuracy help

matrixkid44matrixkid44 Posts: 4
edited 2013-11-29 11:11 in Accessories
I purchased a Gyroscope Module 3-Axis L3G4200D for my school project. I am trying to find the accuracy in ± degrees. I am assuming it should be less than 1-2 degrees? The data sheet doesn't give any information on it. For example the tilt sensor accuracy for Measurement Specialties Inc. is ± 20 degrees. Also for DPS, the website says Three selectable scales: [URL="tel:250%2F500%2F2000"]250/500/2000[/URL]degrees/sec (dps) but does that mean the sample rate? Where the sample rate is 250 samples per second? But when I look at the manual for the explanation of dps it says “This parameter defines the measurement range of the gyroscope in degrees per second (dps)”. I don’t understand how it is 200 degrees/second. It is very important that I find out the accuracy of the Gyroscope. Any help will be appreciated. Thank you.

Comments

  • ratronicratronic Posts: 1,451
    edited 2013-11-29 10:01
    Try Googeling "degrees per second". Good luck with your school project.

    P.S. Also Google "Angular velocity"
  • SRLMSRLM Posts: 5,045
    edited 2013-11-29 11:09
    A MEMS gyroscope measures the rotation rate (aka speed), not the rotational position. So, degree's per second is telling you how fast the gyroscope is rotating.

    You will have a tough time using a gyroscope to tell you the tilt angle? Why? Because the sensor has a zero rate level of up to +- 10 degrees per second (in the best case). Even if you manage to calibrate that out you'll still have to contend with the rate noise density (specified at 0.03dps/sqrt(Hz)). So, you read your gyroscope at 100Hz that's +-0.3dps of error.

    The selectable scale is to select what the maximum measurement can be. If you are in a vehicle (for example) you want want the minimum, because vehicles do not rotate very fast. If you're putting this on a person then you may want the highest rotation rate because you can move quickly.

    The accuracy of a MEMS gyroscope is pretty poor. You can do some tricks to make it better, but it will never be as good as a high end gyroscope.
  • SRLMSRLM Posts: 5,045
    edited 2013-11-29 11:11
    Note also that the tilt sensor that you linked to isn't really comparable to a gyroscope. A better comparison would be with an accelerometer, which can be used as a tilt sensor in static applications.
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