Real-Sim: A Multi-resolution X-in-the-loop Experimental Approach for Testing Connected and Automated Vehicles

Connected and automated vehicle (CAV) technologies need comprehensive testing and evaluation before actual implementation in the real world. However, many inherent technical challenges exist due to the complexity of CAVs. An integrated evaluation platform is needed with vehicle and traffic simulation tools from different domains and X-in-the-loop (XIL) components to fully evaluate all aspects of CAV technologies. In this work, a multi-resolution XIL simulation framework named Real-Sim is presented to support inclusive testing and evaluation of CAVs. Real-Sim approach is simply defined as nearly any part of a system can be "in the loop", either physically or virtually. Oak Ridge National Laboratory (ORNL) has adapted Real-Sim into all its XIL capable laboratories, as well as much of its simulation and model-based design. The foundation of this approach is the system-of-systems concept which has become more relevant as much of transportation research has expanded beyond the vehicle into the traffic networks and traffic control devices. Real-Sim allows researchers to bring real, tangible hardware and software into simulated environments. It applies to a wide variety of applications, including Real controller-Simulated vehicle, Real vehicle-Simulated virtual environment, Real signal controllers-Simulated traffic, etc.