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IMU Sensor

asked 2013-10-17 14:22:31 -0600

Dereck gravatar image

I have a cheap 10-DoF IMU and would like to bring this data into ROS for use in the best way possible. I have it publishing the raw values from the device as an Imu message, but would like to be able to calibrate the biases and convert the data to SI units per the Imu message definition. What is the best way to go about this, are there existing nodes and or libraries for this task? It seems that many IMU's produce an orientation output whereas I need to calculate this on my own but I'd much rather use a library than re-invent the wheel if possible.

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answered 2013-10-18 20:03:32 -0600

Chad Rockey gravatar image

updated 2013-10-18 20:06:03 -0600

Sounds like you most know of what you need to do. I take it you have an /imu_raw topics (composed of raw sensor byte outputs), you should also publish an /imu that's scaled into SI units.

The right messages are:

http://docs.ros.org/api/sensor_msgs/html/msg/Imu.html

http://docs.ros.org/api/sensor_msgs/html/msg/MagneticField.html

http://docs.ros.org/api/sensor_msgs/html/msg/FluidPressure.html

Some available attitude filters: http://mirror.umd.edu/roswiki/imu_filter_madgwick.html

http://www.youtube.com/watch?v=BXsGWoOMtmU

(Maybe one day once I have enough free time/consistent schedule to finish my overhaul of ROS sensor fusion package, graft:)

https://github.com/chadrockey/graft/blob/hydro-devel/test_attitude.launch

One implementation that I know works well is Androids, it wouldn't be too difficult to wrap the AOSP source in a thin ROS wrapper:

https://android.googlesource.com/platform/frameworks/base/+/fca8947f496967ac2097366672a4c725f1b9311f/services/sensorservice/Fusion.cpp

https://android.googlesource.com/platform/frameworks/base/+/fca8947f496967ac2097366672a4c725f1b9311f/services/sensorservice/Fusion.h

Video of Android's algorithm:

http://www.youtube.com/watch?v=C7JQ7Rpwn2k

As for elevation, for my ROSCon talk, I just implemented a quick accumulator that smoothed the altitude offset from where I started the node. The algorithm for altitude from barometric pressure is here:

http://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_atmospheric_pressure_variation

One of these days, I'd like to see a ROS node that polls local barometric pressure references from airports using GPS.

Oh, and there are also a few miscellaneous tools here:

https://github.com/ros-perception/imu_pipeline

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This is exactly what I was looking for, thank you!

Dereck gravatar imageDereck ( 2013-10-19 05:39:44 -0600 )edit

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Asked: 2013-10-17 14:22:31 -0600

Seen: 2,404 times

Last updated: Oct 18 '13