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Create/Roomba odometry

asked 2012-04-16 10:13:36 -0500

gajan gravatar image

updated 2014-01-28 17:11:59 -0500

ngrennan gravatar image

Hi,

I am thinking of getting a iRobot Create or a Roomba for a project which requires some no-so-bad odometry. I have gone through this thread and I have also noticed the following comment on turtlebot_node/roomba_sensor_handler.py

   114     # The distance and angle calculation sent by the robot seems to
   115     # be really bad. Re-calculate the values using the raw enconder
   116     # counts.

If I get a iRobot create I will get only the distance and angle which 'seems to be really bad' since iRobot create does not give out raw encoder counts.

I would like to know if this is still the case ? I prefer iRobot create since it is inexpensive and I don't need the vacuum function. Furthermore, It would be great if any of the users can give me some quantitative values on the odometry errors.

Gajan

p.s: Calling up iRobot support did not help at all :(

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answered 2012-04-16 12:40:11 -0500

Lorenz gravatar image

This was actually my comment :-). My problem was that odometry was actually really broken, i.e. it gave completely wrong values on the roomba. That's why the roomba driver uses the raw encoder values. I didn't try, but i expect the iCreate to give at least correct odometry values but maybe someone who owns one might want to confirm that.

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answered 2015-11-24 03:56:59 -0500

NOTE: Create 2 and Roomba 500/600 firmware versions prior to 3.3.0 return an incorrect value for sensors measured in millimeters. It is recommended that you read the left and right encoder counts directly (packets IDs 43 and 44) and do the unit conversion yourself.
To determine the firmware version on your robot, send a 7 via the serial port to reset it. The robot will print a long welcome message which will include the firmware version, for example: r3_robot/tags/release-3.3.0.

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answered 2012-10-11 00:29:26 -0500

JBuesch gravatar image

Personally I am only working with Roomba5xx and first tried to use the original Create sources to get a turtlebot running (before Roombas were supported at all). The odometry values coming from roomba were terribly inaccurate and also depending on speed of movement. Once I switched to raw encoder values all these problems were gone. I have no absolute values for you (since the error also depends on the acceleration and the floor material), but I can drive several meters and experiencing an error within centimeters (in my case less then 1%). Please feel free to contact me for further information.

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raw encoder is not the original Create sources?

sonictl gravatar imagesonictl ( 2015-11-24 03:15:29 -0500 )edit

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Asked: 2012-04-16 10:13:36 -0500

Seen: 1,927 times

Last updated: Nov 24 '15