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Can a low cost IMU compensate for wheel slip induced heading errors?

asked 2014-06-27 10:14:17 -0600

ChrisL8 gravatar image

I have a two wheeled differential drive robot with a Kinect, similar in shape and form to a TurtleBot. The odometry data provides for beautiful straight lines, but when turning there is a tremendous amount of wheel slip on some surfaces, but little or none on others, making it impossible to predict. The result is very strangely shaped rooms.

I have already experimented with compasses (magnetometers?) and am aware that indoor environments are a sea of magnetic distortion of every kind. So I do not think a "compass" can help.

My limited understanding is that an IMU (AHRS?) can help correct the heading error, but I am concerned that they may not be able to deal with the normal magnetic disturbances inside of a building. I cannot tell from online research if such IMUs are able to compensate for variable magnetic disturbances, such as are found in a building, or if they will be just as poor at estimating a heading as a digital "compass".

I've found two low cost IMUs: CH Robotic's UM 7: www.chrobotics.com/shop/um7-lt-orient... The 9DOF Razor IMU: www.sparkfun.com/products/10736

Will either of these provide an accurate enough heading estimate to correct error caused by wheel slip during rotation in an indoor environment?

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answered 2014-06-28 08:33:30 -0600

updated 2014-06-30 09:20:11 -0600

Measuring the angular rate around the z-axis is performed using a single gydro on the Turtlebot, see Calibrate Odometry and Gyro. Replicating that setup seems like a straightforward approach. You can of course also use a 6 or 9 DOF IMU for the task and just use the z-axis gyro data, ignoring the other axes. Note that you´ll be able to reduce error due to slip, but noise in sensor data will always results in some odometry drift, so you´ll probably want to use AMCL or gmapping to get proper localization and/or mapping.

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That connected the dots for me. I can get a simple gyro much cheaper and experiment with it using the Turtlebot as an example. It seems obvious now, but I needed a pointer. Thank you.

ChrisL8 gravatar image ChrisL8  ( 2014-06-29 19:33:43 -0600 )edit

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Asked: 2014-06-27 10:14:17 -0600

Seen: 1,394 times

Last updated: Jun 30 '14