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Controlling the UR10e with a 3D Mouse

It is possible to control robots using a 3D mouse such as the 3DConnexion SpaceMouse. This allows for controlling the end-effector's position and orientation with one hand. The following steps can be run natively or on the Docker container.

To accomplish this, the spacenav ROS package is used (https://index.ros.org/p/spacenav/) which converts the signal from the 3DConnexion SpaceMouse into various ROS2 messages, including /spacenav/twist (geometry_msgs/msg/Twist). The custom ROS2 package spacenav_converter is used to listen to the /spacenav/twist topic. This twist is turned into a desired pose offset, and used to calculate the next desired pose. The desired pose is then sent as a command to the UR10 via (currently) two possible interfaces:

  • MoveL commands (a linear move command used by the Universal Robots scripting language, URScript) which is sent to the robot (real or simulated via URSim) via the /urscript_interface/script_command topic.
  • Joint positions, calculated using the inverse kinematics in kinematics_utils.py, sent to the robot via the /scaled_joint_trajectory_controller/joint_trajectory topic (if using URsim or the real robot) or the /joint_command topic (if simulating the robot in Isaac Sim).
    • Note The real robot should be controlled using a velocity control interface, outlined in real_experiments.md.

Installation

  1. Ensure you have the SpaceMouse and tf-transformations packages installed (already done in the ProDapt Docker container): 
    sudo apt-get install spacenavd
sudo apt-get install ros-${ROS_DISTRO}-spacenav
sudo apt-get install ros-${ROS_DISTRO}-tf-transformations
  2. Build the spacenav_converter package (only needed to be done once, and after any code change) by running 
    cd ~/prodapt
rosdep install -i --from-path src --rosdistro ${ROS_DISTRO} -y
colcon build --packages-select spacenav_converter

Steps

  1. (If using URSim) Turn on the UR robot (or URSim) and run the UR driver (either locally, in it's own container, or in the ProDapt container). Make sure the robot is externally controllable, such as by following the steps in ursim.md.
  2. (If using Isaac Sim) Start Isaac Sim as detailed in isaacsim.md. Ensure the simulation is started and not paused.
  3. Plug in the SpaceMouse.
  4. Run the spacenav node by running: 
    ros2 run spacenav spacenav_node
    And check that it is publishing by running 
    ros2 topic echo /spacenav/twist
    You should see the topic being published to rapidly, and it should react to manipulating the SpaceMouse.
  5. Run the spacenav_converter package by running 
    cd ~/prodapt
source install/setup.bash

# If using URSim
ros2 run spacenav_converter converter_movel  # or 'converter_joints' to control via joint positions
# If using Isaac Sim
ros2 run spacenav_converter converter_joints --ros-args -p interface:=isaacsim
    Now you should be able to control the robot with the SpaceMouse by moving the SpaceMouse in the desired direction and orientation (i.e., not touching the SpaceMouse should cause the robot to stay still).

Troubleshooting

If you get the error

tf2.ConnectivityException: Could not find a connection between 'base' and 'tool0' because they are not part of the same tree.Tf has two or more unconnected trees.

or another tf error after running the spacenav_converter package, simply kill the UR driver, confirm the robot (simulated or real) is powered on and started, then restart the UR driver. You can check the tf frames are correct and connected by creating a PDF of the frames using

ros2 run tf2_tools view_frames.py

and view the PDF with

xdg-open frames.pdf

If the robot is not moving when using the joint commands on URSim, first confirm that the robot is externally controllable by following ursim.md. If it is, confirm that the /scaled_joint_trajectory_controller/joint_trajectory has a subscriber by running

ros2 topic info /scaled_joint_trajectory_controller/joint_trajectory

If there are no subscribers, kill the URSim container and the UR driver and restart them until the topic appears in ros2 topic list and has a subscriber.

If running ros2 run spacenav spacenav_node is resulting in an error or ros2 topic echo /spacenav/twist is always returning 0 for every value, check the following:

  1. Ensure the Spacemouse is connected
  2. Ensure that the host computer has installed the spacenav packages by running: 
    sudo apt-get install spacenavd
service spacenavd restart
  3. Ensure that the socket is properly formatted by running ls -l /var/run/ | grep 'spnav.sock'. If nothing shows up, something is wrong and the socket is not being created. If the socket appears, ensure the first section reads srwxrwxrwx, and does not start with a d (for directory). If it does, delete it and rerun the previous step and ensure a proper socket is created.