Fuel-Optimal Guidance And Tracking Control of AUV Under Current Interaction

Since there exist more or less sea currents in most of underwater environments, ingenious guidance can lead an AUV to reach the terminal position with reduced consumption of fuel. This may be one of the most critical progresses in the navigation of AUV, since it always suffers from the restricted amount of fuel storage. This paper addresses the development of fuel-optimal guidance and tracking control of AUV when it transfers between two pre-designated points in the region of sea current. Strategy of fuel-optimal guidance is applied to the navigation of an AUV "R-One Robot", developed by IIS, university of Tokyo. In the formulation of this guidance problem, position vector of the vehicle relative to inertial frame is qualified as the state vector, while the vehicle's heading as the input. Total amount of fuel consumption to reach the terminal position is considered as the performance index to be minimized. Optimal guidance law was derived as an ordinary differential equation of two-point boundary value problem on the basis of the calculus of variations. Application of optimal guidance shows especially apparent savings of fuel consumption, when the local distribution of sea current becomes more complicated and irregular.