IMU alignment unclear about lidarslam_ros2 HOT 4 CLOSED

Thanks for the good issue.

For IMU composites in this package, the lidar data does not need to include ring numbers or time like lio-sam.

Currently, the IMU composite for this package is based on Lego-LOAM.

Distortion correction by imu
lidar_undistortion.hpp
https://github.com/rsasaki0109/lidarslam_ros2/blob/foxy/scanmatcher/include/scanmatcher/lidar_undistortion.hpp

For imu-compound, you need to change the scam_period parameter.
I didn't put it in the readme.md, sorry.
I just updated the README.md file.

If you have trouble getting it to work, I recommend looking at the lego-loam issue.

Examples of lego-loam issues
How to align the IMU to Lidar? && Problems with the KITTI dataset
RobustFieldAutonomyLab/LeGO-LOAM#153
Coordinate transformation when use imu
RobustFieldAutonomyLab/LeGO-LOAM#19

I assume that I can simply make sure myself that the axis of the IMU data align with the axis of the lidar? Or should the output of the IMU be identical to the axis of the IMU image? With all the axis modifications as mentioned?

I think the above issues are helpful.

Does the imu data have to contain RAW acceleration data? (incl. gravity) and do i need to compute a covariance matrix?

Now, the imu message must contain angle velocity, acceleration, and orientation(In other words, it must be a 9-axis IMU.). No covariance is required.

Last question: How can it be that the modules start running when I specify use_imu: True at moments when i am not launching the IMU? Shouldnt it wait for imu messages to come in before starting?

Because even when the IMU is not launched, the modules of lego-loam start running.
This package uses only IMU for distortion correction and does not use IMU for preintegration, so I don't think it's a problem to start the module before the imu message comes. But some kind of warning statement might be necessary.

from lidarslam_ros2.

Later on I will add a imu demo using the lego-loam dataset, so please be patient.

jackal_dataset_20170608
https://github.com/RobustFieldAutonomyLab/jackal_dataset_20170608

from lidarslam_ros2.

My apologies.
Apparently there was a bug with respect to the IMU, which caused lidar to jump all over the place.

I've just fixed it.

If you set the scan_period to 0.1, it works fine with any of the data in the above dataset.

from lidarslam_ros2.

I close this issue because there is no recent activity on this issue.
Please open the issue again if you have any further problems.

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