mbot_apriltag

Description

This project offers tools for camera calibration and Apriltag pose estimation, specifically tailored for use with the MBot equipped with a Jetson Nano.

The provided scripts enable users to:

• Stream live camera feeds directly to a browser, allowing for real-time viewing and interaction.
• Publish and subscribe to Apriltag LCM messages.

Installation

Install Apriltag Library

1. Directly install from the official github repo:

   git clone https://github.com/AprilRobotics/apriltag.git

2. Following the install instruction there:

   cd apriltag
   cmake -B build -DCMAKE_BUILD_TYPE=Release
   sudo cmake --build build --target install

Clone this repo

git clone https://github.com/MBot-Project-Development/mbot_apriltag.git

Usage and Features

Run scripts

• python3 video_streamer.py
  • Visit http://your_mbot_ip:5001/video
  • Only shows the video stream to test your camera
• python3 save_image.py
  • Visit http://your_mbot_ip:5001
  • Show the video stream to save image to /images for camera calibration
• python3 camera_calibration.py
  • Use the images from /images and output calibration result as cam_calibration_data.npz. The result will be used directly by apriltag_streamer.py you don't have to modify anything.
• python3 apriltag_streamer.py
  • Visit http://your_mbot_ip:5001/video
  • It runs apriltag detection, when tag is detected, pose estimation will be printed on the screen.
• python3 apriltag_lcm_publisher.py
  • Publish apriltag lcm message over MBOT_APRILTAG_ARRAY
• python3 apriltag_lcm_subscriber.py
  • Listen to MBOT_APRILTAG_ARRAY for apriltag lcm message

Troubleshooting

If encounter error during runtime:"ImportError: libapriltag.so.3: cannot open shared object file: No such file or directory"

1. Verify the Installation Location

   This file is typically installed in a directory like /usr/local/lib or /usr/lib.

   ls /usr/local/lib | grep libapriltag

   ls /usr/lib | grep libapriltag

   • If there is output showing "libapriltag.so.3", we move to the next step

2. Update the Library Cache

   If the library is installed in a standard location but still not found, the system's library cache may need to be updated. Run ldconfig to refresh the cache:

   sudo ldconfig

Authors and maintainers

• The original author of this project is Shaw Sun.
• The current maintainer of this project is Shaw Sun. Please direct all questions regarding support, contributions, and issues to the maintainer. The maintainer is responsible for overseeing the project's development, reviewing and merging contributions, and ensuring the project's ongoing stability and relevance.