Quaternion Output Drift

[Superkato]

Hi,

does my sensor UM-7 has a heavy drift problem?
I’m reading out the Quaternion to get the 360° orientation of the yaw-axis.
When I’m stopping the movement of the turn it still moves very slow like 30-45° away.
In the tech specs you advertising with “0.5 degree angle repeatability”.

Is this a Bug in the AHRS algorithm? I need a very stable 360° yaw-axis orientation RPY (I guess RPY it will not work 360° because you have the atan-problem) or Quaternion with +/-15deg accuracy.

Is there a firmwareupdate available?

Regards,
sven

[chrwebKeymaster]

Hi sven,

To estimate yaw (or the yaw component of the quaternion), the magnetometer on the UM7 must be calibrated. You can use the Serial Interface to collect data, compute the calibration, and write the settings to the device. It can also help to issue a “zero rate gyros” command.

[xuan]

Hi,

I also met this problem. I did mag calibration of UM7, I also “zero gyro rate” and “set mag reference” at start up.
At the beginning the yaw data is good, but when the sensor begin to move, yaw will drift slowly to about 30 degree away.

Is there any methods to fix this?

Thanks,
Xuan

[CalebModerator]

If the yaw angle isn’t remaining accurate, it would be caused by one of the following:

1) The magnetic field is distorted badly enough that the sensor detects it and stops using it,
2) Mag calibration is bad, or
3) The magnetic field is distorted, but not in a detectable way and the magnetic field measurements are pulling the yaw estimate off.

[Superkato]

Could you please show me the link to the Calibration Tutorial?

[Superkato]

IS there a new Firmware? I don’t think its a magnetic field distortion that is affecting the Quart. output.
Even my iphone compass or the Arudino is working fine.
Maybe I’m doing the calibration wrong, is there a PDF?

[CalebModerator]

Check out the “Videos” tab on the UM7 product page: http://www.chrobotics.com/shop/um7-orientation-sensor

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