JosefGst / apriltag_docking_ros

Apriltag Docking ROS

Listens to tf published by e.g.apriltag node to get the position of the dock.

Very simple aproach

Robot will steer directly to the docking tag.

rosrun apriltag_docking_ros simple_apriltag_docking.py

Use ROS Action and pure persuit controller

Robot will aproach charger perpendicular.

roslaunch apriltag_docking_ros apriltag_docking.launch
roslaunch apriltag_docking_ros apriltag_undocking.launch

Usage on TKO-robot

Pupblish the /apriltag_docking/goal topic and specify the "dock_tf_name". The robot will approach the named tf/tag. Subscribe to /apriltag_docking/status and read the "status" value to check the operation.

Parameters

• lookahead_dist_multiplier (double) increasae the distance to the new waypoint
• rotational_vel_gain (double) increase rotational velecity
• linear_vel_gain (double) increase linear velecity
• goal_tolerance (double) The tolerance in meters for the controller in the x & y distance when achieving a goal
• trans_bias Can shift the goal to the right with positive values, negative to the left.
• docking_timeout timeout in seconds. If docking takes longer then docking_timeout, abort.
• tag_on_ceiling (bool) true if tag is mounted on the ceiling

Docking

Subscribed Topics

• /apriltag_docking/goal

  • dock_tf_name: 'dock_name'"

    dock_name is the apriltags tf name

Published Topics

• /apriltag_docking/cancel

  • id: '/apriltag_docking-4-657.69000000'"

    The id need to match with the id form the feedpack topic. Will cancle the docking action.

• /apriltag_docking/feedback

  • distance

    distance to dock

• /apriltag_docking/result

• /apriltag_docking/status

  • status:
    • 1 processing
    • 2 preempted because new goal received
    • 3 goal reached
    • 4 aborted

Unndocking

Subscribed Topics

• /apriltag_undocking/goal

  • distance

    distance in meter the robot should move for undocking. Positive value makes the robot move forward, negative for backwards.

Published Topics

• /apriltag_undocking/cancel

  • id: '/apriltag_docking-4-657.69000000'"

    The id need to match with the id form the feedpack topic. Will cancle the docking action.

• /apriltag_undocking/feedback

  • distance

    distance to dock

• /apriltag_docking/result

• /apriltag_docking/status

  • status:
    • 1 processing
    • 2 preempted because new goal received
    • 3 goal reached
    • 4 aborted

TODO:

• reusable for tags on ceiling

Improvments

• use behavior tree
• make more generic
• add action client