Cooperative Acoustic Navigation Of Underwater Vehicles Without A Dvl Utilizing A Dynamic Process Model: Theory And Field Evaluation

This paper reports the theoretical development and at-sea field evaluation of a novel combined underwater acoustic communication and navigation system, known as cooperative acoustic navigation (CAN), for underwater vehicles (UVs) utilizing a second-order dynamic plant model of the submerged UVs. The present state-of-the-art in CAN is to utilize one-way travel-time acoustic modem telemetry together with purely kinematic, constant-velocity plant process models. We term this approach CAN-KIN. At present, CAN-KIN is utilized with an on-board bottom-lock Doppler velocity log (DVL) providing frequent, high-accuracy velocity corrections. However, DVLs are relatively expensive, have significant power requirements, can be physically large, and have limited acoustic bottom-lock range, which restricts their use to a maximum of 25-420 m above the sea floor. In this study, we investigate the utility of a second-order dynamic UV plant process model in CAN of UVs equipped with an acoustic modem, attitude, and depth sensors, but lacking a DVL, and a surface ship equipped with an acoustic modem and global positioning system. We term CAN utilizing a dynamic model CAN-DYN. This paper reports results from at-sea field trials conducted in the Chesapeake Bay with the Johns Hopkins University Iver3 UV. These experimental results indicate the submerged UV position estimate from CAN-KIN is poor and even unstable in the absence of DVL velocity observations. These field experimental results also show that CAN-DYN performs well without a DVL. Our results suggest CAN-DYN without a DVL does not exhibit instability as does CAN-KIN without a DVL, performs similarly to CAN-KIN with a DVL, and outperforms DVL-based dead reckoning. Additionally, we report an experimental evaluation of the effect of adding (relative) velocity corrections in the form of acoustic range-rate observations to CAN utilizing a dynamic model without a DVL. We conclude that the addition of infrequent velocity observations, such as those provided by acoustic range rate, does not appear to improve the performance of CAN-DYN without a DVL.