Ask Your Question
0

Issue with removing gravity in robot_localization package

asked 2018-05-20 23:10:08 -0500

babazaroni gravatar image

I'm using adafruit bn055 imu board serviced by rtimulib_ros package feeding the robot_localization package. The imu output frame is showing the linear acceleration along the z-axis is around positive 1 when the imu is at rest flat on a level surface. After 60 seconds, the robot_localization /odometry/filtered output is showing the location along z-axis as about the expected negative 17K meters. The parameter imu0_remove_gravitational_acceleration is true in the ekf yaml file. When I change it to false the location along the z-axis changes sign to a positive 17K meters, instead of the expected 0 meters.

Any ideas on how to fix this?

edit retag flag offensive close merge delete

Comments

The imu output frame is showing the linear acceleration along the z-axis is around positive 1 [..]

not an expert here, but doesn't robot_localization (and ROS in general) require SI units to be used here? "positive 1" sounds like your IMU (driver) outputs in gs.

gvdhoorn gravatar image gvdhoorn  ( 2018-05-21 01:54:06 -0500 )edit

1 Answer

Sort by ยป oldest newest most voted
0

answered 2018-05-21 09:34:14 -0500

babazaroni gravatar image

Thanks to the clue from @gvdhoom, I rechecked the distance values and found I had made a mistake. The actual distance when imu0_remove_gravitational_acceleration is false is positive 1700 meters, not 17k meters. Thus the linear acceleration of 1 is in meters, not gravities. I thought the unit was calibrated, so assumed the linear acceleration was in gravity units. Will now need to work on calibration.

edit flag offensive delete link more

Comments

so assumed the linear acceleration was in gravity units

you're talking about your imu output here now, right?

In any case: ROS uses m/s^2 for this, not g. So robot_localization also expects that.

Not claiming that is the cause of what you're seeing, but it's something to fix in any case.

gvdhoorn gravatar image gvdhoorn  ( 2018-05-21 10:15:52 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower

Stats

Asked: 2018-05-20 23:10:08 -0500

Seen: 223 times

Last updated: May 21 '18