Read sensor data with ROS

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Now I want to add some sensors to my robot and read the data from ROS. How can I do it? Do I need to code a Gazebo plugin?

To extract data from Gazebo, you have three options:

1. Use a pre-existing Gazebo Plugin/Sensor that publishes the data to ROS
2. Use a pre-existing Gazebo Plugin or Sensor that publishes the data to the Gazebo Transport Layer. You'll have to access this data (e.g. from a ROS Node) via the Gazebo Transport Library.
3. Write your own custom Gazebo Plugin that publishes sensor data using either of the above methods.