AnsweredAssumed Answered

ADIS 16448 binning issue

Question asked by Chris-12345 on Aug 12, 2016
Latest reply on Aug 25, 2016 by NevadaMark

Hi! I'm currenly running an ADIS 16448 with external clock (820Hz) and read out the gyroscope & accelerometer data (with own hardware, no eval board!). No filtering is enabled and I'm recording a static data set (no dynamics/motion). After removing the biases from the data I plot the histograms of the noise (there was no dynamic) to verify that the resolution and distribution of the values is correct. Unfortunately, I get the following histograms (see attachment for the plots), indicating that the resolution of the gyros & acc is achieved in the data but compared to a normal distribution with same variance as given by the datasheet for the current setting (no filtering -> bandwidth = 330) there are significant differences (gaps in the histograms, especially for the accelerometer data). I re-run the same experiment also with external clock set to 400Hz, no filtering, facing the same issue. In addition, I tested the same setup with a second ADIS unit of the same type resulting in the same problem. I would have expected that the real data is close to normal distribution without any kind of binning issue if bins were chosen equal to the resolution of the sensor. For sake of completeness I also add some register settings of the IMU:

reg. 0x001a has 0x0000: X-axis gyroscope bias offset factor

reg. 0x001c has 0x0000: Y-axis gyroscope bias offset factor

reg. 0x001e has 0x0000: Z-axis gyroscope bias offset factor

reg. 0x0020 has 0x0000: X-axis acceleration bias offset factor

reg. 0x0022 has 0x0000: Y-axis acceleration bias offset factor

reg. 0x0024 has 0x0000: Z-axis acceleration bias offset factor

reg. 0x0026 has 0x0000: X-axis magnetometer, hard iron factor

reg. 0x0028 has 0x0000: Y-axis magnetometer, hard iron factor

reg. 0x002a has 0x0000: Z-axis magnetometer, hard iron factor

reg. 0x002c has 0x0000: X-axis magnetometer, soft iron factor

reg. 0x002e has 0x0000: Y-axis magnetometer, soft iron factor

reg. 0x0030 has 0x0000: Z-axis magnetometer, soft iron factor

reg. 0x0032 has 0x0503: Aux. digital I/O control

reg. 0x0034 has 0x0006: Misc. control

reg. 0x0036 has 0x0000: Internal sample period (rate) control

reg. 0x0038 has 0x0400: Digital filter

reg. 0x0040 has 0x0000: Alarm 1 amplitude threshold

reg. 0x0042 has 0x0000: Alarm 2 amplitude threshold

reg. 0x0044 has 0x0000: Alarm 1 sample size

reg. 0x0046 has 0x0000: Alarm 2 sample size

 

Units inside the plots: acc [m/s^2], gyro [rad/s]

 

I'm a newbie on this blog and in interfacing IMUs so may be I'm doing completely wrong, so any kind of help is appreciated....

Attachments

Outcomes