Inaccurate odometry angle on Create 1

[lopsided98]

Continued from AutonomyLab/create_robot#28...

Where is the bug documented? The only one I know of is an unspecified problem with commands with mm units on the Create 2, nothing about the angle measurement on the Create 1. In fact, the distance measurement (in mm) appears to work correctly.

[lopsided98]

I tried fixing this by integrating the requested velocity and it nominally worked, but there was significant drift (10-20 deg/rotation) that meant it was not much better than the existing situation. I think the best solution is to use a gyroscope.

[jacobperron]

I thought it was documented, but I realize now that I emailed iRobot support a while ago and I was told any firmware version older than 3.4.1 has issues reporting Distance and Angle values.

Yeah, adding a gyroscope will certainly help. We could still try experimenting with lowering the polling frequency if you think it will help, but I don't think I'll have any time in the near future to give it a shot.

[lopsided98]

I think that lowering the polling rate is not worth the effort, given that you would still have problems with the rounding of the values causing errors over time.