ROS1 vs. ROS2 (Short Description)

• Why ROS2?
  • Real time
  • Safety
  • Certification
  • Security
• ROS1 vs. ROS2 - API
  • ROS1: Linux >> TCPROS/UDPROS >> rospy and roscpp >> Master & Your code
  • ROS2 (has more layaers): Linux/Windows/MacOS >> DDS >> rclpy, rclcpp, rcl... >> Your code
• Writing a node
  • ROS1:
    • def callback_number(msg):
    • def callback_reset_counter(req):
    • if __name__ == '__main__':
  • ROS2:
    • class NumberCounterNode(Node):
      • def __init__(self):
      • def callback_number(self, msg):
      • def callback_reset_counter(self, request, response):
    • def main(args=None):
• ROS2 Components
  • ROS1
    • Excutable 01 > Node 01
    • Excutable 02 > Node 02 ...
  • ROS2
    • Solution with ROS1 Nodelets
    • Only one Excutable > Node 01 (component), Node 02 (component), Node 03 (component) ...
• Writig launch files
  • ROS1: .launch file with xml format.
  • ROS2: .launch.py with python format - allows you to customize your luanch file much more than before with xml. Python launch files bring more modularities.
• No more ROS master
  • ROS1: Centralized. Each Node communicates through ROS Master.
  • ROS2: Decentralized. No ROS master. Each node is independent and communicates directly with other Nodes.
• ROS Parameters (ROS1)
  • ROS1: Parameter server is defined in ROS Master.
  • ROS2:
    • No global parameters anymore.
    • Each Node declares and manages its own parameters.
    • Real time.
• ROS Services
  • Synchronous (ROS1)
  • Asynchronous (ROS2) - with option to make them synchronous.
• ROS Actions
  • ROS1:
    • Service is not asynchronous.
    • Communication based on ROS topics.
    • Action Clinet class <------> Action Server class
  • ROS2:
    • Native.
    • Communication based on Topics and Services.
    • Clinet Node <-----> Server Node
• Msg, Srv, Action Definitions
  • Create definitions under folder:
    • msg
    • srv
    • action
  • >> ROS1 compilation, no namespace added.
  • >> After ROS2 compilation, new namespage:
    • msg/...
    • srv/...
    • action/...
  • Ex) Package: my_robot_msgs, Message: Temperature, Service: ActivateButton
    • ROS1
      • my_robot_msgs/Temperature
      • my_robot_msgs/ActivateButton
    • ROS2
      • my_robot_msgs/msg/Temerature
      • my_robot_msgs/srv/ActivateButton

• Building Your Nodes
  • ROS1: catkin_make
  • ROS2: colcon build
• Command Line Tools
  • ROS1: rostopic list...
  • ROS2: ros2 topic list...
• ROS2 Overlays
  
  • ROS1
    • 1. Source >> ROS installation
    • 2. Source >> ROS workspace
  • ROS2
    • 1. Source >> ROS2 installation
    • 2. Source >> ROS2 workspace (overlay 1)
    • 3. Source >> ROS2 workspace (overlay 2)
    • 4. Source >> ....
• ROS - Supported Platforms
  • ROS1: Ubuntu
  • ROS2: Ubuntu, Windows, MacOS