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Calibration procedure for beam robots

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Alexander Thoms edited this page Jul 22, 2022 · 2 revisions

Required software

Our calibration procedure centres around proven methods of extrinsic and intrinsic calibration methods for lidar, camera, and IMU sensors. The following external software is required to fully calibrate all sensors:

git clone git@github.com:BEAMRobotics/kalibr_allan.git && \ 
git clone git@github.com:ethz-asl/kalibr.git

Procedure

  1. Intrinsic IMU calibration

using kalibr_allan, follow Experiment Steps 1-4 as outlined in the repository's README.md, paying attention to manual adjustments that need to be made to variables mat_path and update_rate in ../kalibr_allan/matlab/SCRIPT_allan_matparallel.m and titlestr and mat_path in ../kalibr_allan/matlab/SCRIPT_process_results.m. Upon completion of the previously mentioned steps, results output to console look like ...

{
  "date": "YYYY_MM_DD",
  "method": "kalibr_allan",
  "cov_gyro_noise": 0.00057,
  "cov_accel_noise": 0.00094,
  "cov_gyro_bias":  0.0000037,
  "cov_accel_bias": 0.0000024
}

where:

  • cov_gyro_noise:=gyroscope_noise_density
  • cov_accel_noise:=accelerometer_noise_density
  • cov_gyro_bias:=gyroscope_random_walk
  • cov_accel_bias:=accelerometer_random_walk
  1. https://github.com/ethz-asl/kalibr/wiki (camera doublesphere model intrinsics, camer-to-imu extrinsics, camera-to-camera)
  2. https://www.mathworks.com/help/vision/ref/cameracalibrator-app.html (camera pinhole model intrinsics)
  3. https://www.mathworks.com/help/lidar/ug/lidar-and-camera-calibration.html (camer-to-lidar extrinsics)

Old install notes for Kalibr

Creating Calibration Targets with Kalibr

If you want to be able to create a calibration target using kalibr_create_target, you will also need to install PyX and Latex on your system:

sudo apt-get update
sudo apt-get install texlive-latex-base
sudo pip install pyx==0.12.1

This is only for making a PDF that you can print. For the .YAML files for calibration, create a YAML file as follows (these are values for the big Apriltag grid we have):

target_type: 'aprilgrid'
tagCols: 6
tagRows: 6
tagSize: 0.48355
tagSpacing: 0.300922

More info on this can be found here: https://github.com/ethz-asl/kalibr/wiki/calibration-targets

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