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Setting up a UR robot for ur_rtde_driver
Prepare the robot
For using the ur_rtde_driver with a real robot you need to install the externalcontrol-1.0.urcap which can be found inside the resources folder of this driver.
To install it you first have to copy it to the robot's programs folder which can be done either via scp or using a USB stick. The installation process is similar for CB3 and eSeries robots and will be shown side-to-side in this guide.
On the welcome screen select Setup Robot and then URCaps to enter the URCaps installation screen (For eSeries click on the hamburger menu in the top-right corner to get to the setup menu). There, click the little plus sign at the bottom to open the file selector. There you should see all urcap files stored inside the robot's programs folder or a plugged USB drive. Select and open the externalcontrol-1.0.urcap file and click open. Your URCaps view should now show the External Control in the list of active URCaps and a notification to restart the robot. Do that now.
After the reboot you should find the External Control URCaps inside the Installation section. For this select Program Robot on the welcome screen, select the Installation tab and select External control from the list.
Here you'll have to setup the IP address of the external PC which will be running the ROS driver. Note that the robot and the external PC have to be in the same network, ideally in a direct connection with each other to minimize network disturbances. The custom port should be left untouched for now.
To use the new URCaps, create a new program and insert the External Control program node into the program tree:
If you click on the command tab again, you'll see the settings entered inside the Installation. Check that they are correct, then save the program.
Prepare the ROS PC
For using the driver make sure it is installed (either by the debian package or built from source inside a catkin workspace).
Extract calibration information
Each UR robot is calibrated inside the factory giving exact forward and inverse kinematics. To also make use of this in ROS, you first have to extract the calibration information from the robot.
Though this step is not necessary, to control the robot using this driver, it is highly recommended to do so, as endeffector positions might be off in the magnitude of centimeters.
For this, there exists a helper script:
$ rosrun ur_calibration calibration_correction \
_robot_ip:=192.168.56.101 \
_robot_name:=ur10_example \
_output_package_name:=my_calibrations \
_subfolder_name:=etc
For the parameter robot_ip insert the ip on which the ROS pc can reach the robot. The robot_name is an arbitrary name you can give to the robot. It is recommended, to choose a unique name that can be easily matched to the physical robot.
The script will then extract the calibration information from the robot and convert it to a yaml syntax that can be used by the robot_description.
The resulting yaml file is stored in the package specified in the output_package_name parameter inside the folder subfolder_name with the name robot_name*_calibration.yaml*. The parameter subfolder_name is optional and defaults to etc if not given.
Note: You'll have to provide the name of an existing package. It is recommended to have a package storing all calibrations of all UR robots inside your organization. This way, the extraction as described in this package has only to be performed once and the calibration can be reused by other users. To create a new package, go to your catkin_workspace's src folder and call
catkin_create_pkg my_calibrations
It is recommended to adapt the new package's package.xml with a meaningful description.
Start the robot driver
To actually start the robot driver use one of the existing launchfiles
$ roslaunch ur_rtde_driver <robot_type>_bringup.launch robot_ip:=192.168.56.101 \
kinematics_config:=$(rospack find my_calibrations)/etc/ur10_example_calibration.yaml
where <robot_type> is one of ur3, ur5, ur10, ur3e, ur5e, ur10e. Note that in this example we load the calibration parameters for the robot "ur10_example". If the parameters in that file don't match the ones reported from the robot, the driver will output an error during startup.
For more information on the launchfile's parameters see its own documentation.
Once the robot driver is started, load the previously generated program on the robot panel and execute it. From that moment on the robot is fully functional. You can make use of the pause function or even stop the program. Simply press the play button again and the ROS driver will reconnect.