Integral Line-of-Sight Guidance of Underwater Vehicles Without Neutral Buoyancy

Abstract

This paper analyzes an integral line-of-sight guidance law applied to an underac-tuated underwater vehicle. The vehicle is rigorously modeled in 5 degrees of freedom usingphysical principles, and it is taken into account that the vehicle is not necessarily neutrallybuoyant. The closed-loop dynamics of the cross-track error are analyzed using nonlinear cascadedsystems theory, and are shown to achieve uniform semiglobal exponential stability. Hence, theintegral line-of-sight guidance law compensates for the lack of neutral buoyancy, and it is nolonger necessary to assume that the vehicle is perfectly ballasted. The exponential convergenceproperties of the guidance law are demonstrated in simulations of an autonomous underwatervehicle.