For people learning robotics, the ability to have access to real robots is fun and useful, but not everyone has access to a real robot. Simulators are a great tool when we have limited access to a real robot. They were created for testing the behavior of algorithms before trying them on a real robot. This is why simulators exist.
In this chapter, you learned how to create a 3D model of your own robot. This included a detailed explanation of how to add textures and creating joints, s as well as how to use a node to move the robot.
Then, we introduced Gazebo, a simulator where you can load the 3D model of your robot and simulate it moving and sensing a virtual world. This simulator is widely used by the ROS community, and it already supports many real robots in simulation.
We saw how we can reuse parts of other robots to design ours. In particular, we included a gripper and added sensors, such as a laser range finder and a camera.
As you can see, you don't have to create a robot from scratch...