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ROS Hand-eye calibration client for Roboception's rc_visard

This node provides ROS service calls and topics to calibrate the rc_visard to a robot (aka hand-eye calibration).

It also provides the new or pre-existing calibration via /tf or /tf_static. The default behavior is to request the existing calibration of the rc_visard once on startup, broadcast it (latched) on /tf_static and only broadcast again if the advertised ROS services calibrate or get_calibration are called.

The calibration routine consists of several steps:

  1. Setting calibration parameters, i.e. grid size and mounting, via dynamic reconfigure.

  2. For a user-defined number of robot calibration poses repeat

    1. Move the robot to the pose (calibration grid must be visible in the rc_visard's view).
    2. Send the robot pose to rc_visard (set_pose)

  3. Trigger the calibration tranformation to be calculated (calibrate).

After the calibration transform is calculated and tested, it should be saved to the rc_visard (save_calibration).

For detailed instructions on the calibration routine consult the rc_visard manual: https://doc.rc-visard.com.

Installation

This package relies on git submodules for the cpr library which need to be initialized before building from source.

git submodule update --init --recursive

Configuration

Parameters

  • host: The IP address or hostname of the rc_visard that should be calibrated
  • rc_visard_frame_id: Name of the frame on the rc_visard when calibrating. Default: "camera"
  • end_effector_frame_id: Name of the frame calibrated to when using a robot_mounted (see below) rc_visard. Default: "end_effector".
  • base_frame_id: Name of the frame calibrated to when using a statically (externally) mounted rc_visard (robot_mounted == false). Default: "base_link"
  • calibration_request_period: Decimal number, controls the requesting of calibration from the rc_visard. Default: 0.0.
    • If positive: Interval in seconds for automated requests to get the latest calibration
    • If zero: Only request once on startup (default)
    • If negative, the calibration is never requested.
    • In any case, new results will be broadcast when the services calibrate or get_calibration (see further below) of this node are called.
  • calibration_publication_period: Decimal number, controls broadcasting of the calibration on /tf or /tf_static. Default: 0.0
    • If positive: Interval in seconds.
    • If negative or zero, the calibration is broadcast on /tf_static only when changed in a manual or periodic calibration request (default)

Dynamic reconfigure parameters

  • grid_width: The width of the calibration pattern in meters
  • grid_height: The height of the calibration pattern in meters
  • robot_mounted Whether the camera is mounted on the robot or not

Services

The following services are offered to follow the calibration routine:

  • reset_calibration: Deletes all previously provided poses and corresponding images. The last saved calibration result is reloaded. This service might be used to (re-)start the hand-eye calibration from scratch.
  • set_pose: Provides a robot pose as calibration pose to the hand-eye calibration routine.
  • calibrate: Calculates and returns the hand-eye calibration transformation with the robot poses configured by the set_pose service. Broadcast the result via /tf or /tf_static.
  • get_calibration: Returns the existing hand-eye calibration transformation. Broadcast the result via /tf or /tf_static.
  • save_calibration: Persistently saves the result of hand-eye calibration to the rc_visard and overwrites the existing one. The stored result can be retrieved any time by the get_calibration service.
  • remove_calibration: Removes the stored hand-eye calibration on the rc_visard. After this call the get_calibration service reports again that no hand-eye calibration is available. Periodic broadcasting via /tf will be stopped.

Launching

Using command line parameters:

rosrun rc_hand_eye_calibration_client rc_hand_eye_calibration_client_node _host:="10.0.2.44"