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

On Debian/Ubuntu add the ROS sources and

sudo apt-get install ros-${ROS_DISTRO}-rc-hand-eye-calibration-client

From Source

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

• device: The ID of the device, i.e. Roboception rc_visard sensor. This can be either:
  • serial number, e.g. 02912345. IMPORTANT: preceed with a colon (:02912345) when passing this on the commandline or setting it via rosparam (see https://github.com/ros/ros_comm/issues/1339). This is not neccessary when specifying it as a string in a launch file.
  • user defined name (factory default is the name of the rc_visard's model), must be unique among all reachable sensors.
• host: If device is not used: 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.
• tcp_rotation_axis:, TCP rotation axis for 4 DOF robot calibration (-1 for general robot)
• tcp_offset: Offset from the TCP for 4 DOF robot calibration

Services

The following services are offered to follow the calibration routine:

• reset_calibration [rc_hand_eye_calibration_client/Trigger]: 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 [rc_hand_eye_calibration_client/SetCalibrationPose]: Provides a robot pose as calibration pose to the hand-eye calibration routine.
• calibrate [rc_hand_eye_calibration_client/Calibration]: Calculates and returns the hand-eye calibration transformation with the robot poses configured by the set_pose service. Broadcasts the result via /tf or /tf_static.
• get_calibration [rc_hand_eye_calibration_client/Calibration]: Returns the existing hand-eye calibration transformation. Broadcasts the result via /tf or /tf_static.
• save_calibration [rc_hand_eye_calibration_client/Trigger]: 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 [rc_hand_eye_calibration_client/Trigger]: 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.
• set_calibration [rc_hand_eye_calibration_client/SetCalibration]: Sets the hand-eye calibration transformation. The calibration transformation is expected in the same format as returned by the calibrate and get_calibration calls. save_calibration must be called to make the calibration transformation persistent.

Launching

Using command line parameters:

rosrun rc_hand_eye_calibration_client rc_hand_eye_calibration_client_node _device:=:<serial_number>