INTERFACING THE CODA AND CADCON SIMULATORS: A MULTI-FIDELITY SIMULATION TESTBED FOR AUTONOMOUS OCEANOGRAPHIC SAMPLING NETWORKS Erik Albert, Jonathan Bilodeau, and Roy M. Turner * Department of Computer Science, University of Maine 5752 Neville Hall, Orono, ME 04469 USA {albert17,bilodeau,rmt}@umcs.maine.edu Abstract Simulation testbeds are important for develop- ing complex systems, such as autonomous oceano- graphic sampling networks (AOSNs), as they allow the development and testing of control mechanisms without incurring the cost or risk of using real ve- hicles. Over the past several years, two simulators for AOSNs, CoDA and CADCON, have been de- veloped. The CoDA simulator is a multi-fidelity simulation testbed for the intelligent AOSN control mechanisms being developed at the University of Maine. While it can simulate AOSNs at a range of fidelities, it lacks truly high-fidelity simulation of the environment and of vehicle dynamics. CADCON is a high-fidelity multi-AUV simulation testbed devel- oped at the Autonomous Undersea Systems Insti- tute. This paper reports on work done to combine the two simulators into the CoDA/CADCON sim- ulator, which is capable of a range of AOSN sim- ulations, from faster-than-real-time simulations of aggregate AOSN control mechanism properties to high-fidelity, real-time simulations of an AOSN as it carries out missions. Introduction Work on developing complex systems is facilitated by the availability of simulators. This is especially true if the system is expensive or contains many expensive or difficult to obtain components. Such is the case for autonomous oceanographic sampling networks (AOSNs) [4], which are composed of many autonomous underwater vehicles (AUVs) and other instrument platforms. * This work was funded in part by grants N0001-14-96- 1-5009, N0001-14-98-1-0648, and N00014-00-1-0614 from the Office of Naval Research. The content of this paper does not necessarily reflect the position or the policy of the U.S. government, and no official endorsement should be inferred. Authors are listed alphabetically; contact author is Roy M. Turner (rmt@umcs.maine.edu). The authors thank Andrew Sylvia for his work on part of the simulator and also the other members of the Maine Software Agents and Artificial Intelligence Laboratory (MaineSAIL.umcs.maine.edu). There are several existing simulators for AOSNs (e.g., [10; 16; 3]). These typically either simulate the high-level behavior of an AOSN (e.g., SAMON [10]) or the low-level behavior of the vehicles within the AOSN (e.g., CADCON [3]). The CoDA (Cooperative Distributed AOSN con- troller) project [17] takes a different approach. The CoDA simulator, described in more detail elsewhere [16], is meant to allow AOSNs to be simulated at several different levels: it is a multi-fidelity simula- tor. For example, once the designers have completed an overall design for an AOSN control mechanism, they can use CoDA to quickly implement a high- level model and run simulation experiments. As ex- perience with the design accrues, the model can be made incrementally more detailed, so that higher- fidelity simulations can be run. Different pieces of the model can be simultaneously at different lev- els of detail. For example, the high-level behav- ior of a group of AOSN agents (i.e., the vehicles and other instrument platforms) can be simulated by rules that model the overall effects of coopera- tion protocols, while other parts of the model (e.g., task assignment) can be modeled at a higher fidelity, perhaps even with the code that would be fielded in an actual AOSN. Multi-fidelity simulation promotes rapid prototyping and faster-than-real-time simu- lation (e.g., by discrete-event simulation) of over- all system properties by selectively avoiding high- fidelity, continuous time-dependent pieces of the simulator, yet it also allows more detailed simula- tions to be done later for accuracy. Until the current phase of the CoDA project, while the simulator has been able to simulate AOSNs at a range of fidelity levels, it has not been able to support truly high-fidelity simulations of ve- hicle dynamics and sensors. This paper reports on the current phase, in which work that has been done add this capability to CoDA by interfacing it with the Autonomous Undersea Systems Insti- tute’s (AUSI’s) CADCON high-fidelity simulator. The combined simulator, called CoDA/CADCON, This paper appears in the Proceedings of the 13th International Symposium on Unmanned Untethered Submersible Technology (UUST), Durham, NH, August, 2003. Copyright c  2003 AUSI and the authors.