Author Topic: Accelerometer and Gyro Measurements for IMU  (Read 1692 times)

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Offline salirazaTopic starter

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Accelerometer and Gyro Measurements for IMU
« on: April 13, 2009, 06:42:17 PM »
Hi everyone,

I am using the functions accelerometer_ACCM3D, and gyro_SEN00741 for getting the measurements from the accelerometer=ADXL330Z and rategyro=IDG-300.

      a0=accelerometer_ACCM3D(a2dConvert10bit(0));
      a1=accelerometer_ACCM3D(a2dConvert10bit(1));
      a2=accelerometer_ACCM3D(a2dConvert10bit(2));
      a3=gyro_SEN00741(a2dConvert10bit(3));
      a4=gyro_SEN00741(a2dConvert10bit(4));

I need to convert the readings from the accelerometer (used as tilt sensors) into radians, similarly the readings from rate gyro are to be converted in radians/sec. if anypne can help/guide in this matter I'll be grateful.

Regards,

Ali

Offline TrickyNekro

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Re: Accelerometer and Gyro Measurements for IMU
« Reply #1 on: April 14, 2009, 04:04:08 AM »
well.... first of all you gotta filter the reading, and I don't really know which method you prefer...
Secondly... the ADXL330 should have a form on how to convert volts to radial speed....
Supposing you get the 10bit convention the max value you get is 1023...
Now.... Let's say that you use the 5V volt reference....
Then we have a formula that is 5 / 1023 = x
Suppose you multiply the readings with this x factor you get the volts at the ADC channel...
Then use the ADXL330 formula to convert to speed...
Same with the accelerometer....

But keep in mind you gotta filter the data with a method cause cause of vibrations
on any axis, should you have problem, especially with the accelerometer....
Gyros aren't so prone to noise, but can be affected....
Also, applications using such data are control applications.... Keep in mind making a
smart algo for the filtering.... And plan the best case and worst case scenario timing...
for not having any problems,
Suppose your code is smart enough add this as a parameter....


Best Regards,
Lefteris, Greece
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

 


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