IMU not added to the graph: cannot interpolate imu transform

[VK]

Hi Mathieu,

I'm trying to compute stereo odometry using IMU for initialization with left and infrared images from D435i.
For launching rtabmap_ros I'm using the following:

roslaunch rtabmap_ros rtabmap_imu.launch \
   stereo:=true \
   rtabmapviz:=true \
   approx_sync:=false \
   use_sim_time:=true \
   frame_id:=D435_link \
   left_camera_info_topic:=/D435/infra1/camera_info \
   right_camera_info_topic:=/D435/infra2/camera_info \
   left_image_topic:=/D435/infra1/image_rect_raw \
   right_image_topic:=/D435/infra2/image_rect_raw \
   wait_imu_to_init:=true \
   imu_topic:=/rtabmap/imu \
   compressed:=true \
   queue_size:=30 \
   args:="-d \
      --Odom/ResetCountdown 1 \
      --Rtabmap/StartNewMapOnLoopClosure true \
      --Odom/Strategy 0 \
      --Vis/FeatureType 0 \
      --Rtabmap/DetectionRate 5 \
      --Rtabmap/ImagesAlreadyRectified false \
      --RGBD/OptimizeMaxError 5.0 \
      --RGBD/LoopClosureReextractFeatures true \
      --Kp/DetectorStrategy 0 \
      --RGBD/NeighborLinkRefining true"

In the custom rtabmap_imu.launch file I've just added a node for madgwick filter  (from ros imu tools) for orientation computation from D435i raw accel and gyro measurements.
Even if I have already used the above successfully with an other dataset also recorded with D435i, now I receive the following warning and imu is not used from rtabmap:
[ INFO] [1623069339.896805890]: rtabmapviz started.
[ WARN] [1623069364.219142565, 1622552179.257503632]: Still waiting for data on topic /imu/data_raw...
[ WARN] [1623069364.219344809, 1622552179.257503632]: Still waiting for data on topic /imu/data_raw...
[ WARN] (2021-06-07 15:36:11.716) Odometry.cpp:302::process() Updated initial pose from xyz=0.000000,0.000000,0.000000 rpy=0.000000,-0.000000,0.000000 to xyz=0.000000,0.000000,0.000000 rpy=-0.045161,0.373951,-1.603868 with IMU orientation
[ WARN] (2021-06-07 15:36:11.716) Transform.cpp:517::getTransform() No transform found for stamp 1622552179.243977! Earliest is 1622552179.275116
[ WARN] (2021-06-07 15:36:11.716) Transform.cpp:517::getTransform() No transform found for stamp 1622552179.243977! Earliest is 1622552179.275116
[ INFO] [1623069371.835923653, 1622552179.457486548]: Odom: quality=0, std dev=99.995000m|99.995000rad, update time=0.119310s
[ WARN] (2021-06-07 15:36:11.857) Transform.cpp:517::getTransform() No transform found for stamp 1622552179.243977! Earliest is 1622552179.275116
[ WARN] [1623069371.857708592, 1622552179.479215499]: We are receiving imu data (buffer=81), but cannot interpolate imu transform at time 1622552179.243977. IMU won't be added to graph.

I think that the only difference between my current dataset and the the one I used in the past, is that in this dataset the compressed images were recorded, thus I use ros image transport for decompression.
Is it possible that the error above has to do with Image transport long delay for decompression?
I double checked my bag and there are no sync issues or time gaps between images and imu  topics....

Any ideas?

Thanks a lot!!
Any ideas how to solve it?

[matlabbe]

Hi,

Is it happening continuously? If no, maybe just some lags when replaying the bag.

The warning "Odometry.cpp:302::process() Updated initial pose from" is okay.

For this warning "We are receiving imu data (buffer=81), but cannot interpolate imu transform at time 1622552179.243977. IMU won't be added to graph. ", check if the /rtabmap/imu data has a continuous rate.

cheers,
Mathieu

[Masoumeh]

Dear Mattieu,

I have also the same error, but in the published topic, i do not have /rtabmap/imu!
how can i resolve this issue?

thanks

[matlabbe]

See http://wiki.ros.org/rtabmap_ros/Tutorials/StereoHandHeldMapping#Bring-up_example_with_RealSense_cameras