Simulators of ROS

One of the open source robotic simulators tightly integrated with ROS is Gazebo (http://gazebosim.org). Gazebo is a dynamic robotic simulator with a wide variety the robot models and extensive sensor support The functionalities of Gazebo can be added via plugins. The sensor values can be accessed to ROS through topics, parameters and services. Gazebo can use when your simulation needs full compatibility with ROS. Most of the robotics simulators are proprietary and expensive; if you can't afford it, you can directly use Gazebo without any doubt.

Figure 13: Gazebo simulator