The application of statistical theory of nonlinear systems to ship motion performance in random seas¹

Article type: Research Article

Authors: Vassilopoulos, Lyssimachos A.

Affiliations: Department of Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A.

Note: [1] Paper presented at the First Ship Control Systems Symposium held in Annapolis, Maryland, U.S.A. on November 15–17, 1966 under the auspices of the U.S. Navy marine Engineering Laboratory.

Abstract: The contents of the paper stem from a preliminary inquiry into the problem of modelling a surface ship in irregular seas as a nonlinear, time-invariant system when its motions are large. The main objective of the study is to introduce to the naval architectural profession the Wiener theory of nonlinear systems and to evaluate its potential in the solution of such problems. After a brief historical review, the basic results of the theory are summarized and attention is fixed to explicit, time-domain, functional representations of the output of a nonlinear system in terms of input. The Volterra and Wiener kernels and their transforms are defined and methods for their determination are briefly mentioned. It is then shown how the output of such a system can be characterized when the input is periodic, aperiodic or random. The paper concludes with example applications to ship motion problems and a discussion of several issues associated with this type of analysis. Among tip items discussed are the wave-induced ship resistance in random seas, uncoupled nonlinear motions, such as roll, and the extension of the theory to multi-input, multi-output systems.

DOI: 10.3233/ISP-1967-1415002

Journal: International Shipbuilding Progress, vol. 14, no. 150, pp. 54-65, 1967