Minimizing Ship Motions. A Practical Approach to the Optimal Control of Systems with Application to the Control of a Submarine in a Random Sea

摘要

The basic problem considered is the design of an optimal control for a system subjected to disturbances. Although deterministic disturbances are discussed, the majority of the work and the three examples deal with random or stochastic disturbances. The principal contention of this work is that one cannot determine an 'optimal' control for a system without optimizing a performance criterion which is a measure of the performance of the entire system. The Max-Ranking Performance Criterion which is developed has the capability for considering a wide variety of system variables. The use of this criterion does not depend upon any knowledge of the system interactions; the designer need only present his specifications for the system operation in the form of a ranking array. The nonlinear systems are analyzed using a statistically equivalent linear system. Random search techniques are then applied to three systems which are subjected to random disturbances: the design of a threeparameter control for a third-order system; the design of a five-parameter control for the roll control of a submarine; and the design of a nine-parameter control for the coupled pitch-heave control of a submarine. (Author)