Usage

This chapter explains how to use the ur_robot_driver

Quick start

Driver startup

To start it with hardware, use:
```
$ ros2 launch ur_robot_driver ur_control.launch.py ur_type:=<UR_TYPE> robot_ip:=<IP_OF_THE_ROBOT> launch_rviz:=true
```
After starting the launch file start the external_control URCap program from the pendant, as described here.
To run it with URSim check details about it in this section.

To use mocked hardware (capability of ros2_control), use use_mock_hardware argument, like:

$ ros2 launch ur_robot_driver ur_control.launch.py ur_type:=ur5e robot_ip:=yyy.yyy.yyy.yyy use_mock_hardware:=true

Sending commands to controllers

Once the driver is started, you can use it like any other ROS robot arm driver by sending trajectories to the /scaled_joint_trajectory_controller/follow_joint_trajectory action. If you’re new to that, please have a look at the section “Move the robot”.

Robot frames

While most tf frames come from the URDF and are published from the robot_state_publisher, there are a couple of things to know:

The base frame is the robot’s base as the robot controller sees it.
The tool0 is the tool frame as calculated using forward kinematics. If there is no additional tool configured on the Teach pendant (TP) and the URDF uses the specific robot’s calibration the lookup from base -> tool0 should be the same as the tcp pose shown on the TP when the feature “Base” is selected.

Troubleshooting

This section will cover some previously raised issues.

I started everything, but I cannot control the robot

The driver is started, but trajectory execution doesn’t work. Instead, the driver logs

Can't accept new action goals. Controller is not running.

The External Control program node from the URCap is not running on the robot. Make sure to create a program containing this node on the robot and start it using the “Play” button . Inside the ROS terminal you should see the output Robot connected to reverse interface. Ready to receive control commands.

Note

When interacting with the teach pendant, or sending other primary programs to the robot, the program will be stopped. On the ROS terminal you will see an output Connection to reverse interface dropped.. Please see the section Continuation after interruptions for details on how to continue.

In general, make sure you’re starting up the robot as explained here.

When starting the program on the teach pendant, I get an error “The connection to the remote PC could not be established”

Make sure, the IP address setup is correct, as described in the setup guides (CB3 robots, e-Series robots)

Note

This error can also show up, when the ROS driver is not running.

When starting the driver, it crashes with “Variable ‘speed_slider_mask’ is currently controlled by another RTDE client”

Probably, there is a fieldbus enabled on the robot. Currently, this driver cannot be used together with an enabled fieldbus. Disable any fieldbus to workaround this error. ROS 1 driver issue #204 contains a guide how to do this.

I sent raw script code to the robot but it is not executed

On the e-Series the robot has to be in remote control mode to accept script code from an external source. This has to be switched from the Teach-Pendant.

Using the dashboard doesn’t work

On the e-Series the robot has to be in remote control mode to accept certain calls on the dashboard server. See Available dashboard commands for details.