angular velocity on /imu topic broken

[ihadzic]

I have recently upgraded the OpenCR firmware on my TB (I am now in the 1.1.2, before I was in 1.0.7). It looks like the units on /imu topic have been switched to radians (from raw ADC readings), but the numbers appear broken. I make the robot spin by exactly 1rad/s (verified correct by external means) and the imu/ topic reports 0.12 on z-axis angular velocity.

I believe the problem is that the calculations assume that the gyroscope range is +/-250 degrees (cf. the value of GYRO_FACTOR constant in turtlebot3_sensor.h), but the FS_SEL bits are still set to +/- 2000 range (see the register write to GYRO_CONFIG register in MPU9250.cpp)

[chcbaram]

@ihadzic

You are right. Gyro is configured as +/-2000dps and Accel is configured as +/-2g
It will be fixed next update.

[robotpilot]

@ihadzic, @chcbaram
This bug fix will be included in the next TurtleBot3 version upgrade.
I sincerely appreciate your feedback and will continue to provide better software in the future. :)
Thank you so much.

[robotpilot]

@OpusK, Does this software update include a workaround for this issue?

[ihadzic]

I have just updated to 1.1.13 and it looks like the gyroscope is still reporting incorrect reading. Looking at the source code, a comment has been added next to GYRO_FACTOR definition (and the math in the comment is correct), but the value has not been changed (it's still the old 0.000133)

#define GYRO_FACTOR                       0.000133  // pi / (131 * 180)      adc * 1/16.4 = deg/s => 1/16.4 deg/s -> 0.001064225157909 rad/s

[OpusK]

@robotpilot, @ihadzic,

This issue has not been resolved in the 1.1.13 release.
I think it will be fixed in the next release.

[routiful]

Hi :) @ihadzic

You can watch the code is replaced.

https://github.com/ROBOTIS-GIT/OpenCR/blob/develop/arduino/opencr_arduino/opencr/libraries/turtlebot3/include/turtlebot3/turtlebot3_sensor.h#L30

It will be updated soon.

Thanks

[routiful]

Hi again @ihadzic

We update new firmware (version 1.2.0) :) Thank you to your contribution!