automaticaddison/cobot_arm_examples

Examples of basic ROS 2 Publishing and Subscribing

cobot_arm_examples

This package provides basic ROS 2 examples to demonstrate fundamental concepts such as publishing/subscribing and parameter handling. Despite its name, it does not specifically deal with robot arms but serves as a general introduction to ROS 2 programming.

Overview

The cobot_arm_examples package includes simple implementations of ROS 2 nodes in both Python and C++. It covers:

• Publishers and Subscribers
• Parameter declaration and handling

Contents

Python Examples

• minimal_py_publisher.py: A simple publisher node that sends "Hello World" messages.
• minimal_py_subscriber.py: A subscriber node that listens for messages on a topic.
• minimal_py_parameters.py: Demonstrates parameter declaration and handling in ROS 2.

Topics used in Python examples:

• /topic: Used by both the publisher and subscriber for string messages.

C++ Examples

• minimal_cpp_publisher.cpp: A C++ implementation of a simple publisher node.
• minimal_cpp_subscriber.cpp: A C++ implementation of a subscriber node.
• minimal_cpp_parameters.cpp: Demonstrates parameter handling in C++.

Topics used in C++ examples:

• /topic_cpp: Used by both the publisher and subscriber for string messages.

Prerequisites

• ROS 2 Iron

Building the package

To build this package, clone this repository into your ROS 2 workspace and build it using colcon:

cd ~/ros2_ws/src
git clone https://github.com/automaticaddison/cobot_arm_examples.git
cd ..
colcon build --packages-select cobot_arm_examples
source ~/ros2_ws/install/setup.bash

Running the examples

After building and sourcing the package, you can run the examples using the ros2 run command.

Python Examples

Run the publisher:

ros2 run cobot_arm_examples minimal_py_publisher.py

In another terminal, run the subscriber:

ros2 run cobot_arm_examples minimal_py_subscriber.py

To run the parameters example:

ros2 run cobot_arm_examples minimal_py_parameters.py

C++ Examples

Run the publisher:

ros2 run cobot_arm_examples minimal_cpp_publisher

In another terminal, run the subscriber:

ros2 run cobot_arm_examples minimal_cpp_subscriber

To run the parameters example:

ros2 run cobot_arm_examples minimal_cpp_parameters

Modifying Parameters

You can modify parameters at runtime using the ros2 param set command. For example:

ros2 param set /minimal_parameter_cpp_node velocity_limit 3.14

Dependencies

This package depends on the following ROS 2 packages:

• rclcpp
• rclpy
• rcl_interfaces
• std_msgs

These dependencies are listed in the package.xml file and will be automatically resolved when building with colcon.

License

This project is licensed under the Apache License 2.0. See the LICENSE file for details.

Author

Addison Sears-Collins