...USARSim provides embodyment (sensors and platforms) and environments for a physics-based robotic simulation while ROS provides leading edge control algorithms.
USARSimROS provides for auto-discovery of the simulated robots and sensors and connects these robots to the appropriate ROS control topics. Through the use of auto-discovery, robotic platforms and sensors may be easily changed and connect to the ROS control stack. Repeatable experiments are possible in a variety of environments and will hopefully lead to more robust and capable algorithms.