koide3
what is invert_imu
On default, the invert_imu is enabled but the localization just failed when the car turns. Then I turned it off, and everything works perfectly fine. Could you give me a hint of what this invert_imu does?
Hi @HaoyunXu , If it is enabled, all IMU data will be inverted (multiplied by -1). It was made for backward compatibility with a specific sensor. I think I will make it disable by default. Thanks for reporting.
I did a test, it seems that when using hdl_400.bag.tar.gz with imu, the imu's acc and gyro in the bag, we should enable invert_imu_acc and invert_imu_gyro.
Note:
imu's orientation is not used.
Before using imu, we should firstly transform imu's data into laser, if they are not aligned. Am i correct @koide3 :)?
Yes, the acc and gyro in the bag are inverted, and thus invert_imu_acc and invert_imu_gyro need to be enabled. plot_status.py is useful to validate the IMU directions that plots prediction errors with/without IMU. If the errors with IMU are smaller than without IMU, your IMU configuration should be fine.
In case the LIDAR and IMU have different coordinate systems, it's better to change odom_child_frame_id to the imu frame. Then, input point cloud is transformed in the IMU frame, and localization should be done without problems.