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Calibration of ADXL377
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Calibration of ADXL377

by amitshishodia on Fri May 31, 2019 7:02 am

Hello Sir/madam
I have ADXL377, its already calibrated or not?
if it is not calibrated so how to calibrate ADXL377 Accelerometer , i am connected ADXL377 board to feather M0 adalogger.

amitshishodia
 
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Re: Calibration of ADXL377

by adafruit_support_bill on Fri May 31, 2019 7:22 am

MEMS sensors like the ADXL377 typically have some zero-offset error and critical applications may require calibration for maximum accuracy. Gravity is the simplest calibration standard to use for accelerometers.

However, gravity is not the ideal standard for calibrating low- sensitivity devices like the ADXL377, since it does not come close to the full-scale measurement range of the device. For that you would need a test jig capable of producing consistent acceleration conditions for calibration.

https://learn.adafruit.com/adafruit-ana ... erence-4-3

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Re: Calibration of ADXL377

by amitshishodia on Mon Jun 03, 2019 3:43 am

Hello
i have read your post and share link, In this link calibration of sensor ADXL335 and i have use ADXL377 sensor this accelerometer sensor range is high 200g for higher range One commonly used technique is to drop the accelerometer from a known height and measure the negative acceleration at impact.
.
Tell me what known height for measuring negative impact
and for celebration of ADXL377 Arduino Uno board is necessary, because i have not Arduino board i have Feather M0 Adalogger, so can i use Feather board for celebration of ADXL377.
Please tell me how i am calibrate my ADXL377 accelerometer sensor and arduino board is necessary for this calibration.

amitshishodia
 
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Re: Calibration of ADXL377

by amitshishodia on Mon Aug 19, 2019 5:50 am

ADXL 377 calibration


Hello Sir

With the help of your guidence, I have calibrated accelerometer sensor. i used 2 methods for calibration, for higher range using x, y, and z Raw value and
Code: Select all | TOGGLE FULL SIZE
int gX1 = -((((xRaw - rawLowX1) * refRange) / rawRangeX) + (refLow));
. Second for low range calibratin i used
Code: Select all | TOGGLE FULL SIZE
long xScaled = map(xRaw, RawMin, RawMax, -200000, 200000);
. Because higer range calibration produced error in low range that why i used both method for calibration of sensor.

with the help of RawMin and RawMax
Code: Select all | TOGGLE FULL SIZE
int RawMin = -12; int RawMax = 1014;
i calibrated the low value of acceleration x, y and z are 0g, 0g, and 1g same for all other axes. but after someday I again start a test, the sensor produced an error. for removing error I again change in the value of RawMin and RawMax.
Sir, I don't want to change in RawMin and RawMax value. i want if i have done calibration it remains the same for a long time.

Please give the solution to my problem.

Thank you.

amitshishodia
 
Posts: 60
Joined: Thu May 30, 2019 7:29 am

Re: Calibration of ADXL377

by adafruit_support_bill on Mon Aug 19, 2019 6:21 am

I again start a test, the sensor produced an error.

What kind of error?

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Re: Calibration of ADXL377

by amitshishodia on Mon Aug 19, 2019 7:09 am

adafruit_support_bill wrote:
I again start a test, the sensor produced an error.

What kind of error?


Like, when I calibrated it give acceleration 0g, 0g, and 1g in x, y, and z-axis for +z direction. After 3-4 day i again start test then it gives -1g, 0g, and 1g or maybe different value of g in x, y, and z-axis for the same calibration. for getting again 0g, 0g, and 1g in x, y, and z-axis I do again calibration.

amitshishodia
 
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Re: Calibration of ADXL377

by adafruit_support_bill on Mon Aug 19, 2019 8:06 am

In this line of code:
Code: Select all | TOGGLE FULL SIZE
long xScaled = map(xRaw, RawMin, RawMax, -200000, 200000);

You are scaling a raw range of about 1000, to a measurement range of 400000. So any error due to noise or offset will be multiplied by a factor of 400.

Looking only at temperature effects: a 1ยฐC change in temperature can result in as much as 30mG offset in the Z axis. Multiplied by 400, that is 1.2G.

Using a high range sensor such as the ADXL377, it is not possible to make precise measurements at low acceleration values - especially when using a relatively low-resolution (10 bit) ADC such as the one in the Arduino.

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Re: Calibration of ADXL377

by amitshishodia on Wed Sep 18, 2019 6:24 am

Hello Sir,

I am looking for a calibration certificate of ADXL377. Your company or Analog device has provided any calibration certificate of ADXL377.

amitshishodia
 
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Re: Calibration of ADXL377

by adafruit_support_bill on Sun Sep 22, 2019 6:55 am

These boards are individually tested for basic functionality. But they are not calibrated at the factory, so there is no calibration certificate.

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Re: Calibration of ADXL377

by amitshishodia on Fri Sep 27, 2019 7:40 am

Hello Sir
i have calibrated ADXL377 sensor by using angular velocity method by using formula
Code: Select all | TOGGLE FULL SIZE
int gX1 = -((((xRaw - rawLowX1) * refRange) / rawRangeX) + (refLow));
. and we calculation of reference g, i have used http://www.calctool.org/CALC/phys/newtonian/centrifugal. here i give radius in mm or angular velocity in RPM. according to this link, we have calculated g value(reference) in different rpm and check sensor value(observe) on the same rpm. both reference value of g and the observed value of g approximately the same.
But when i apply simple harmonic motion(sin wave at different frequency and amplitude) in sensor and measure g value it approx 4 times of angular velocity method calibration.

Example- in angular velocity method distance between motor shaft to sensor 55mm and motor angular velocity is 570rpm calculated value and observer value of g approximately 20g.
But when we use our same sensor and (simple harmonic motion) apply sin wave of frequency 40 Hz and displacement (d)3.1mm our sensor give acceleration approx 80g. but calculated value is 20g linkhttps://www.mide.com/pages/simple-harmonic-motion-calculator
so my question is why our calibration is wrong for simple harmonic motion.?

amitshishodia
 
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Re: Calibration of ADXL377

by adafruit_support_bill on Fri Sep 27, 2019 8:46 am

So, if you run continuously at 570 RPM you get a reading of 20G, but with harmonic motion you are getting 80G?

Please a diagram of your test setup and details of your calibration procedure.

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Please be positive and constructive with your questions and comments.