Camera

Tower-mount camera calibration

On workstation or your PC

  1. To shh the youbot (in all terminals):

yb2

Note

alias yb2=ssh -X robocup@youbot-brsu-2-pc2

  1. Export the youbot ssh alias

export_yb2

Note

alias export_yb2=export ROS_MASTER_URI=http://youbot-brsu-2-pc2:11311

On robot

  1. Launch the robot

roslaunch mir_bringup robot.launch

  1. Launch Nav2d (to visualize the robot in Rviz)

roslaunch mir_2dnav 2dnav.launch

  1. Run calibration

roslaunch mir_calibrate_pick calibrate_pick.launch

A small gui window to adjust the pose of the end-effector in terms of XYZRPY will appear.

  1. Place a small round object on the ground (at approx. 25 cm from the center of the front wheel)

On workstation or your PC

  1. Run rviz

rosrun rviz rviz

  1. Load the camera_calibration_config.rviz config and set the global frame to base_link

    Ensure to enable raw_color_pcl and camera_calibration_obj_pose. You can see an arrow pointing away from the robot.

  2. Adjust the values in the pose mockup gui, so that the beginning of the arrow matches the center of the round object.

Note

Make sure the object is not too far away from the robot and the Z value is slightly above the object.

../_images/camera_calib_side.png

Camera calibration example side view

../_images/camera_calib_top.png

Camera calibration example top view

On robot

  1. Test the calibration in another terminal

  rosrun mir_calibrate_pick calibrate_pick_client_test.py

The robot will move towards the gripper and move the end-effector of the arm close the object based on the given offset.

  1. If the final end-effector position is not properly aligned to the desired goal position, in the robot navigate to the robot urdf configuration and edit the robot.urdf.xacro

/ros/noetic/robocup/src/mas_industrial_robotics/mir_robots/mir_hardware_config/youbot-brsu-2/urdf/robot.urdf.xacro

<xacro:realsense_d435 name="arm_cam3d" parent="base_link">
  <origin xyz="0.30 -0.05 0.80" rpy="0.00 1.137 0.0" />
</xacro:realsense_d435>

Adjust the values of xyz and rpy to account for the offset according to the values set in step 8 and repeat from step 8.

  1. If the final end-effector position is properly aligned to the desired goal position, the camera calibration is complete.

  2. Terminate all operations and relaunch the robot to continue.

RealSense2 camera

How to use the RealSense2 camera

  1. Installation

Go to the intel-ros github page. Clone the realsense repository in your catkin workspace inside src:

git clone git@github.com:intel-ros/realsense.git

  1. Camera Output

Run the following to get access to the camera:

roslaunch realsense2_camera rs_rgbd.launch

Open rviz to visualize the camera output.

  1. Configure camera output (OPTIONAL)

Run the following to open the rviz configuration window:

rosrun rqt_reconfigure rqt_reconfigure

You can also try to change the “octree_resolution” value:

cd *catkin workspace*/src/mas_perception/mcr_scene_segmentation/ros/config

  1. Setup Base Frame

Run the following:

rosrun tf static_transform_publisher x y z roll pitch yaw base_link camera_link 100

where x, y, z are the distances and roll, pitch, yaw are the rotations from the base_link to the camera_link.

To visualize your frames in rzviz, add the TF feature in the rviz menu.

  1. Save Point Clouds

If it’s your first time saving point clouds, you need to choose where you want to save them and enable data collection:

cd *catkin workspace*/src/mas_perception/mcr_scene_segmentation/ros/launch

Change the value of “dataset_collection” from “false” to “true”. Change value of “logdir” from “/temp/ to the path in your computer where you want to save the files.

Run the following to get access to the point clouds given by the camera:

roslaunch mcr_scene_segmentation scene_segmentation.launch input_pointcloud_topic:=/camera/depth_registered/points

Publish the message ‘e-start’:

rostopic pub /mcr_perception/scene_segmentation/event_in std_msgs/String "data: 'e_start'"

Publish the message ‘e-add-cloud-start’:

rostopic pub /mcr_perception/scene_segmentation/event_in std_msgs/String "data: 'e_add_cloud_start'"

This last one will save the current point cloud of the observed object in your system.

Warning

Sometimes the camera won’t save the point cloud (don’t worry, not your fault). Just try a different position for the object until it works.

  1. Visualize Point Cloud

Run the following in the folder where you saved the point clouds:

pcl_viewer *.pcd file you want to open*