Connected and automated vehicles (CAVs) can bring safety, mobility, and energy
benefits to transportation systems. Ideally, CAV applications would be fully
evaluated and validated prior to real-world implementation. However, many
technical challenges in both software and hardware hinder the process. To
comprehensively evaluate all aspects of CAV applications, an integrated
evaluation environment is needed with various simulation tools from different
domains. In the current literature, there lacks a well-developed interface to
enable multi-resolution simulation of vehicle, traffic, virtual environment, and
hardware-in-the-loop (HIL) simulation. In this work, a modular and flexible
interface is developed to enable multi-resolution vehicle and traffic
co-simulation for CAV applications. This interface is built upon Oak Ridge
National Laboratory’s (ORNL’s) Real-Sim approach, can support various simulation
tools and real-time X-in-the-loop (XIL) simulations, and is based on network
communication protocols. The network communication delays are analyzed for
simultaneous connection of up to 20 simulators. Then, two example applications
are studied to demonstrate the potential usage of the Real-Sim interface: (1) a
centralized merging scenario where the dynamics of two ego vehicles are emulated
with detailed vehicle and powertrain dynamics models and (2) a
signal-controller-in-the-loop (SCIL) evaluation where one intersection of the
simulated traffic scenario is controlled by a physical signal controller. This
Real-Sim interface is a tool that allows researchers to bring real, tangible
hardware and software into simulated environments to comprehensively evaluate
and support a wide variety of CAV applications.
