The C-API driver is (currently) only compatible with CB2 controllers running a 1.x version of Polyscope. It cannot be used on CB3 or newer controllers.

UR Control Box

  • ssh into the control box (instructions for how to do this can be found on the support site)
  • Create a base directory for source code, e.g. ur_ros_ctrl
  • Clone the industrial_core (hydro-devel) (Note: this is a fork of the main repo. See and universal_robot (hydro-devel-c-api) repositories into this directory

  • Download the latest UR C-API version and extract it into this directory

  • cd ~/ur_ros_ctrl/universal_robot/ur_ctrl_server/scripts

  • Run ./ to create symbolic links for scons compiler

  • cd .., then run scons to compile the control server

  • Two binaries should be generated in the ./bin folder. The ur_test_server executable can be used for testing communication or the controller without commanding the actual robot. ur_ctrl_server is the actual robot-side driver.

ROS-enabled UR master machine

  • Clone the industrial_core (hydro-devel) and universal_robot (hydro-devel-c-api) repositories into your catkin workspace. You also need to install the ros-controls repositories ros_control, ros_controllers, realtime_tools, and control_toolbox. There might be updated Debian packages for these.

  • You should also install rqt, rqt-robot-dashboard, and rqt-robot-monitor
  • After making, you should be done installing

Starting the Controller Drivers

[ System design/ROS Industrial workshop slides ] You might want to begin by using the test binary on the robot to test communication, then use the actual controller once you feel you have the hang of it.

  • Begin by stopping the tablet controller using ./ in the root directory. To restart the tablet controller, you should bring down the ROS driver, then run ./

  • Start the server on the robot by running the binary in ur_ctrl_server/bin. You should not need to touch this terminal again. The real controller will print out junk until the interface is opened.

  • On the UR master, run roslaunch ur_c_api_bringup ur<5/10>_bringup.launch robot_ip:=<robot's ip>

  • Bring up the rqt GUI by running rqt in the terminal.

  • Enable the plugins "UR Dashboard" and "UR Joint Control" and customize the layout to your liking
  • We will now begin bringing up the robot controller. Click the 3rd button in the dashboard to open the interface to the robot.
  • Once the state reads "NO_POWER", click the 4th button to turn on the power to the robot
  • Once the state reads "INITIALIZING", click the 5th button to unlock the safety brakes to release
  • Use the joint control GUI to calibrate each of the joints, moving each of them in one direction until they all say "RUNNING". Once all the joints are callibrated, all of the buttons should turn green and all of the states will say "RUNNING".
  • Bringing up the robot can be a testy process and you might have to restart a few times to get it to work. However, once the joints are calibrated, the system is fairly stable.

Managing the controllers

You can load/start/stop/unload controllers using the controller_manager utility rosrun controller_manager controller_manager help. You can also find a GUI interface for managing controllers in rqt. See the ros_control page for more information.

Control Modes

There are multiple ways of actuating the joints provided in the UR C API, but only one can be activated at a time. Right now there are 2 interfaces supported, the velocity (prefix: vel_) and position/velocity/acceleration (prefix: pva) interfaces. Every controller which uses that particular interface should be prefixed accordingly.

In addition, there are *_enable_mode controllers. To run a controller like pva_forward_ctrl, pva_enable_mode must also be started. To switch to, say vel_trajectory_ctrl, you must first stop pva_enable_mode (and optionally pva_forward_ctrl), then start both vel_enable_mode and vel_trajectory_ctrl to enable the trajectory controller. This feature keeps two interfaces from running simultaneously.

Test Code

You can find test code for two controllers in ur_controllers/test. Be careful, as this code will move the robots. However, they assume that the appropriate controllers are already running.

Wiki: ur_c_api_bringup (last edited 2015-04-17 08:06:43 by GvdHoorn)