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RobotOperation.md

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IFRA-Cranfield: ROS2 Sim-to-Real Robot Control

Robot Operation: Instructions

This document provides detailed instructions for operating a robot in the ROS2 Sim-to-Real Robot Control framework. It also provides information about the usage of additional features and tools for both Gazebo Simulation and Real Robot Control.

ROBOT MOVEMENT

Robot movements in the ROS2 Sim-to-Real Robot Control framework are controlled via specific ROS2 Actions. The two main ROS2 actions for movement are /Move and /RobMove.

/Move ROS 2 Action

The /Move action allows you to execute various robot motion commands based on specific movement types and parameters such as speed, joint positions, Cartesian paths, and rotations.

Robot Movements are executed from a single ROS 2 Node in ros2_SimRealRobotControl. A Robot Motion request consists of a simple ROS2 Action (/Move) call, where the following parameters must be specified:

  • The ACTION that is going to be executed.
  • The speed at which the robot will execute the action.
  • The value of the action to be executed.

Actions can be executed by running the following commands in the Ubuntu Terminal:

  • MoveJ: The Robot moves to the specific waypoint, which is specified by Joint Pose values.

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveJ', movej: {joint1: 0.00, joint2: 0.00, joint3: 0.00, joint4: 0.00, joint5: 0.00, joint6: 0.00}, speed: 1.0}"  # (6-DOF)
ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveJ', movej: {joint1: 0.00, joint2: 0.00, joint3: 0.00, joint4: 0.00, joint5: 0.00, joint6: 0.00, joint7: 0.0}, speed: 1.0}" # (7-DOF)

  • MoveL: The Robot executes a CARTESIAN/LINEAR path. The End-Effector orientation is kept constant, and the position changes by +-(x,y,z).

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveL', movel: {x: 0.00, y: 0.00, z: 0.00}, speed: 1.0}"

  • MoveR: The Robot rotates the selected joint a specific amount of degrees.

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveR', mover: {joint: '--', value: 0.00}, speed: 1.0}"

  • MoveROT: The Robot rotates/orientates the End-Effector frame according to the input: EulerAngles(yaw,pitch,roll). THE ROT(yaw,pitch,roll) determines the ADDED ROTATION of the End-Effector, which is applied to the END-EFFECTOR COORDINATE FRAME.

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveROT', moverot: {yaw: 0.00, pitch: 0.00, roll: 0.00}, speed: 1.0}"

  • MoveRP: End-Effector rotation AROUND A POINT -> The Robot rotates/orientates + moves the End-Effector frame according to the input: EulerAngles(yaw,pitch,roll) + Point(x,y,z). THE ROT(yaw,pitch,roll) determines the ADDED ROTATION of the End-Effector, which is applied to the END-EFFECTOR COORDINATE FRAME, AROUND THE (x,y,z) POINT.

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveRP', moverp: {x: 0.00, y: 0.00, z: 0.00, yaw: 0.00, pitch: 0.00, roll: 0.00}, speed: 1.0}"

  • MoveG: The Gripper fingers move to the specific pose. The "moveg" value is a value between 0-100, representing the gripper opening percentage.

    ros2 action send_goal -f /Move ros2srrc_data/action/Move "{action: 'MoveG', moveg: 0.0, speed: 1.0}"

  • NOTE: The Robot JOINT SPEED is controlled by the "speed" parameter when executing the specific ROS2.0 action. The value must be (0,1]. being 1 the maximum velocity and 0 the null velocity (which is not valid -> A small value must be defined, e.g.: 0.01 represents a very slow movement).

/RobMove ROS 2 Action

The /RobMove action is used to move the robot’s end-effector to a specific end-effector pose. It allows for two types of movement:

  • PTP (Point-to-Point): The robot moves directly to the target pose via an optimal path in joint space.
  • LIN (Linear): The robot moves in a straight line between its current pose and the target pose.

To execute a /RobMove action, the following parameters need to be defined:

  • The TYPE of movement: It can be Point-to-Point ("PTP"), or LINEAR ("LIN").
  • The speed at which the robot will execute the action.
  • The POSE, (POSITION - x,y,z + ROTATION - qx,qy,qz,qw).

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

ros2 action send_goal -f /Robmove ros2srrc_data/action/Robmove "{type: '---', speed: 1.0, x: 0.0, y: 0.0, z: 0.0, qx: 0.0, qy: 0.0, qz: 0.0, qw: 0.0}"

It is recommended to combine /Robmove with /Robpose (ROS 2 Topic, see below). This ROS 2 topic publishes the current (real-time) pose of the Robot's end-effector, which helps the user to define the robot's next pose.

MONITOR ROBOT STATE

Monitoring the robot’s state and pose is crucial for real-time feedback and system control. There are two main tools for this:

  • RobotState.py script (JOINT VALUES).
  • /RobPose ROS 2 Topic (END-EFFECTOR POSE).

RobotState.py script

The RobotState.py script allows the user to get the state of the robot in joint values, by simply executing the following command:

ros2 run ros2srrc_execution RobotState.py

RobPose ROS 2 Topic

The /Robpose topic publishes the real-time pose of the robot’s end-effector in terms of position and orientation. You can monitor the current pose by subscribing to this topic:

ros2 topic echo /Robpose

EXTRA: Spawn Object to a Gazebo Environment

The SpawnObject.py script allows users to spawn objects into the Gazebo simulation environment. The objects must be defined in a .urdf file and placed in the appropriate package folder (/urdf/objects folder inside the specified package).

ros2 run ros2srrc_execution SpawnObject.py --package "{}" --urdf "{}.urdf" --name "{}" --x {} --y {} --z {}