Navigation of unmanned underwater vehicles for scientific surveys

Possible navigation methods for unmanned underwater vehicles are described and the limits of their accuracy are reviewed. The best approach seems to be the use of a sparse network of bottom-laid acoustic transponders giving only sporadic coverage of the area, together with a high-accuracy dead reckoning system based on a bottom-referenced acoustic log and a low-cost inertial navigator used as a precision gyrocompass. The likely performance and operating costs are discussed. Accuracy requirements are considered in detail