ros2_RobotSimulation: ROS2 Execution

The ros2_execution package allows us to run programs/sequences by executing ROS2 Actions one after the other. This can be done thanks to the ros2_execution.py script, which contains the Action Clients for the ROS2 Actions (defined in ros2_actions package), and executes the robot movements one after the other according to a pre-defined sequence of actions.

Nowadays, every single robot manufacturer has its own programming language, a customised way of generating/executing programs and a tailored user-interface, which makes it difficult to combine different robots and recycle programs/sequences. However, the combination of ROS2 and MoveIt!2, the Robot Simulation packages in ros2_RobotSimulation and the ROS2 Robot Triggers in ros2_actions presents a huge opportunity to create a tool that executes programs and sequences for different robots/end-effectors in the exact same way.

And that is what ros2_execution basically does! It replicates the essential feature of executing pre-defined or pre-generated robot programs/scripts, but with an extra feature: It could perfectly execute a program for a UR, ABB, Fanuc, Kuka, Panda... with a simple requirement: The Hardware must support ROS2.

Please find below a brief explanation about how the programs are executed and how the sequences are defined and saved in the system.

Program execution

Programs can be executed by running the following command in the Ubuntu Terminal:

ros2 run ros2_execution ros2_execution.py --ros-args -p PROGRAM_FILENAME:="---" -p ROBOT_MODEL:="---" -p EE_MODEL:="---"'

• The PROGRAM_FILENAME parameter is the name of the file which contains the program. The program is saved in a .txt file, and the name must be inputted excluding the ".txt" extension.
• The ROBOT_MODEL parameter represents the model of the robot. Options: irb120 - irb1200 - irb6640 - cr35ia - ur3 - ur5 - ur10 - iiwa - panda.
• The EE_MODEL parameter represents the model of the end-effector. Options: schunk - panda_hand - none.

Pre-defined sequence: Format

The pre-defined programs are saved inside the /programs folder as .txt files. Every single line of the .txt file represents an execution step (being the 1st line: 1st step, 2nd line: 2nd step, ...), and it is represented as a python dictionary. The following list showcases how every single ROS2 Action has to be inputted in the program.txt:

• For MoveJ ---> {'action': 'MoveJ', 'value': {'joint1': 0.0, 'joint2': 0.0, 'joint3': 0.0, 'joint4': 0.0, 'joint5': 0.0, 'joint6': 0.0}, 'speed': 1.0}
• For MoveL ---> {'action': 'MoveL', 'value': {'movex': 0.0, 'movey': 0.0, 'movez': 0.0}, 'speed': 1.0}
• For MoveR ---> {'action': 'MoveR', 'value': {'joint': '---', 'value': 0.0}, 'speed': 1.0}
• For MoveXYZW ---> {'action': 'MoveXYZW', 'value': {'positionx': 0.0, 'positiony': 0.0, 'positionz': 0.0, 'yaw': 0.0, 'pitch': 0.0, 'roll': 0.0}, 'speed': 1.0}
• For MoveXYZ ---> {'action': 'MoveXYZ', 'value': {'positionx': 0.0, 'positiony': 0.0, 'positionz': 0.0}, 'speed': 1.0}
• For MoveYPR ---> {'action': 'MoveYPR', 'value': {'yaw': 0.0, 'pitch': 0.0, 'roll': 0.0}, 'speed': 1.0}
• For MoveROT ---> {'action': 'MoveROT', 'value': {'yaw': 0.0, 'pitch': 0.0, 'roll': 0.0}, 'speed': 1.0}
• For MoveRP ---> {'action': 'MoveRP', 'value': {'yaw': 0.0, 'pitch': 0.0, 'roll': 0.0, 'x': 0.0, 'y': 0.0, 'z': 0.0}, 'speed': 1.0}
• For MoveG:
  • To Open Gripper ---> {'action': 'GripperOpen'}
  • To Close Gripper ---> {'action': 'GripperClose'}
• For the ros2_grasping feature:
  • To attach object to end-effector ---> {'action': 'Attach', 'value': {'object': '---', 'endeffector': '---'}}
  • To detach object ---> {'action': 'Detach', 'value': {'object': '---'}}