The hitch_estimation_apriltag_array package is intended to estimate the angle between a mobile base and a cart that is hitched to its rear. The calculation is performed by estimating the 6DOF transform between a rear-facing RGB camera assumed to be mounted at the rear of the mobile base and an array of forward-facing April tags mounted at the front of the cart.

April tag sizes, frames, topics, etc are set in the launchers

• apriltag_ros.launch.xml
• apriltag_array_pose_estimation.launch.xml
• hitch_joint_state_estimation.launch.xml

Estimate the angle between the mobile base and the trailer with

ros2 launch hitch_estimation_apriltag_array hitch_estimation_apriltag_array.launch.xml

Instead, if you wish to estimate only the transform of the April tag array with respect to the RGB camera, comment out the last include, namely

<include file="$(find-pkg-share hitch_estimation_apriltag_array)/launch/hitch_joint_state_estimation.launch.xml"/>

The utility of this package is to facilitate motion planning and control during autonomous navigation of articulated vehicles. See video: