Stabilizing Control of an Unmanned Surface Vehicle Pushing a Floating Load

In this paper, the automatic control of a single unmanned surface vehicle (USV) pushing a floating load is developed and theoretically analyzed. This represents a challenging control problem, since the manipulated load is underactuated and its open-loop dynamics is inherently unstable. Thus, a stabilizing controller must be designed. To this end, a scheme that combines partial feedback linearization with local linearization of the remaining nonlinear terms is proposed. Such scheme simplifies the design of a variable structure controller, that has robustness characteristics to parametric uncertainties and matched disturbances. The proposed closed-loop control system has local stability properties. Small-scale experimental results in calm waters, and simulation results, illustrate the performance of the proposed control system.