Same data but not always successed. Jump & Large velocity sometimes.

[j953302]

Hello @rsasaki0109 Thanks for your soon reply. You have help me clean one bug in #23 . And I have add the check delta_t code in imu_preintegration.cpp.

However, when I keep play my bag data, I hope it could finish a loop. But it will happen a lot of problem randomly. Here I record some result here. And I knew you are busy. But if you are free, please help me check my data or how could I avoid this randomly problem. Thank you very much.

bag file: https://drive.google.com/drive/folders/1Ov5nnFHmqO3qDI_GLPtWwOS9HZtOQiP0?usp=sharing

Result1: First half everything is perfact. But other will jump out. And I will get Rviz2 info: [rviz2]: Message Filter dropping message: frame 'base_link' at time 1686970685.207 for reason 'Unknown'

Result2: Same. But this time it jump early than result1. And show more info like: [imu_preintegration]: Large velocity, reset IMU-preintegration!

If I have other new found, I will update here. Thank you very much.

[rsasaki0109]

@j953302 Can you provide the yaml file?

[j953302]

@rsasaki0109 Sure. But I didn;t change anything. lio.zip If you need more information, please tell me.

[rsasaki0109]

The following output is being produced. Are you using image_projection (which is a node for scan distortion correction)? Not using it can lead to a decrease in estimation accuracy.

[image_projection-4] Failed to find match for field 'time'.
[image_projection-4] [ERROR] [image_projection]: Point cloud is not in dense format, please remove NaN points first!
[image_projection-4] [WARN] [image_projection]: Point cloud timestamp not available, deskew function disabled, system will drift significantly!
[INFO] [image_projection-4]: process has finished cleanly [pid 1039676]

The accuracy will degrade if the following is not estimated with an actual IMU. For example, the following package could be useful: https://github.com/gaowenliang/imu_utils

      imuAccNoise: 3.9939570888238808e-03
      imuGyrNoise: 1.5636343949698187e-03
      imuAccBiasN: 6.4356659353532566e-05
      imuGyrBiasN: 3.5640318696367613e-05

[rsasaki0109]

Setting ndt_resolution to 1.0 or slowing down the rosbag playback speed may improve the trajectory estimation. Note that lowering ndt_resolution reduces robustness against violent movement and rotation.

Also, if ndt_num_threads is 0, the pc load may be too high, so adjusting it for your pc may help stabilize scan matching.

[rsasaki0109]

And I have add the check delta_t code in imu_preintegration.cpp.

By the way, it would be great if you could give me a PR for this. If it's too much trouble, I can fix it myself.

[rsasaki0109]

@j953302 In my environment, there were no issues with scan maching failure even when playing the rosbag at 1.0x with your parameters, so I suspect the problem lies with your PC specs. I would recommend adjusting the ndt_num_threads or lowering the speed of rosbag playback or using a higher spec PC.

[j953302]

The following output is being produced. Are you using image_projection (which is a node for scan distortion correction)? Not using it can lead to a decrease in estimation accuracy.

[image_projection-4] Failed to find match for field 'time'.
[image_projection-4] [ERROR] [image_projection]: Point cloud is not in dense format, please remove NaN points first!
[image_projection-4] [WARN] [image_projection]: Point cloud timestamp not available, deskew function disabled, system will drift significantly!
[INFO] [image_projection-4]: process has finished cleanly [pid 1039676]

The accuracy will degrade if the following is not estimated with an actual IMU. For example, the following package could be useful: https://github.com/gaowenliang/imu_utils

      imuAccNoise: 3.9939570888238808e-03
      imuGyrNoise: 1.5636343949698187e-03
      imuAccBiasN: 6.4356659353532566e-05
      imuGyrBiasN: 3.5640318696367613e-05

[image_projection-4] Failed to find match for field 'time'. -> This problem will always occur but it will not affect my reconstruct. Is it ok?

And because imu_utilts is just for ros1. Maybe later I try to change it into ros2 and try it.

[j953302]

And I have add the check delta_t code in imu_preintegration.cpp.

By the way, it would be great if you could give me a PR for this. If it's too much trouble, I can fix it myself.

It's my pleasure, but I didn't change too much code. I change in image_projection.cpp. And add some code before it check if point cloud is dense cloud point. Like below:

  std::vector<int> indices;

  pcl::removeNaNFromPointCloud(*laserCloudIn, *laserCloudIn, indices);
  if (laserCloudIn->is_dense == false) {
    RCLCPP_ERROR(
      get_logger(), "Point cloud is not in dense format, please remove NaN points first!");
    rclcpp::shutdown();
  }

[j953302]

Hello, it work stably after I change ndt_num_threads and rosbag play speed. Here I put my result here. And I will keep optimate this result. Thank you very much.

[rsasaki0109]

The issue seems to be resolved, so I'll close this issue.