Abstract—Sophisticated unmanned underwater vehicles require automatic motion control systems. Common approach to synthesis of such systems does not consider parametric uncertainty of underwater vehicles and nonlinearity of some of their elements. Also, interaction between manipulated variables is not commonly considered. The paper is dedicated to mathematical modeling of a multivariable control system for an unmanned underwater vehicle vertical motion, considering its interval parametric uncertainty. Research resulted into a tridimensional mathematical model of an underwater vehicle motion in a vertical plane; a model of a propulsion and steering system of an underwater vehicle and a method of robust controller parametric synthesis for such systems.