fusion of IMU and odometry

[acp]

Dear people.

I am trying to fuse IMU with odometry base on this launch file: zed_visual_odom_true_bag_play.launch





Then I used the following launch file to make a 3D map using  with:

stereo version of rtabmap using  left/right images? (subscribe_stereo:=true)

 zed_visual_odom_true_bag_play.launch


Then I compare the odometry from the fused (imu + odom) with the one generated by  rgbd_odometry.


I show the picture with the comparison of the two odoms.





1.- The tow odoms are shifted. The red one is the one generated by thergbd odometry which produces a good map, the blue one is the one generated by the fusion which generates a not good map as you can see it in the following.




The question is:

What can I improve to get a better map or tune?


Thank you :)

[Williamc17]

Hi acp,

I am also trying to fuse IMU with odometry based on zed-mini. A few days ago, I happened to see this post Fusion on zed and imu, but the map drifted immediately in the forum. Two most important things we should do. I make a note as follows:

1. To get a good fusion on between IMU and vo, the transform between the sensors should be very precise. You can use kalibr tool to get this information and get more precise TF.

2. When using /camera/odom, you don't need to use visual_odometry node. rtabmap should be subscribed to /odometry/flltered if you want to use odometry output from IMU and /camera/odometry fusion, otherwise IMU is ignored if rtabmap is subscribed directly to /camera/odom.

These are my suggestion:
First of all, have you recalibration your camera/IMU to get a precise transform between the sensors?
Secondly, I don't know whether you subscribe the right nodes?

Cheer,
Williamc17

[acp]

Hi Williamc17


Thank you for your answer.


Yea I did camera and imu calibration using https://github.com/ethz-asl/kalibr/wiki/camera-imu-calibration


I have used /mavros/imu/data_raw and not /mavros/imu/data. I hope it is ok :)

The calibration is here: camchain-imucam-homeacpcatkin_wskalibr-cdedynamicsdata.yaml


I do not know how and where and how to set up that transformation.


In fact I do not want to use

/stereo_camera/odom

 because the child_frame_id is

/zed_center

 I think that  /vo shall be fine.


you can see this post:   http://official-rtab-map-forum.206.s1.nabble.com/Outdoor-3D-mapping-with-GPS-and-IMU-td5427.html#a5558 


Secondly, I don't know whether you subscribe the right nodes?
Which nodes are you talking about?


I am looking forward to your replay