Optimal design of an automatic control system for submerged hydrofoil boats operating in a random seaway

A novel design procedure is applied to hydrofoil boat control systems; it is referred to as the Specific Linear Optimal Control Optimization Problem (SLOCOP). Also described is the minimization algorithm, GRASP, which is used to produce numerical SLOCOP solutions. SLOCOP requires that the boat motion satisfy linear differential equations and results in a linear feedback law. The forcing function is a discretized Pierson-Moskowitz random seaway. The free-surface effects, orbital particle velocity, and unsteady lift are modeled as sums of outputs of linear oscillators subject to random initial conditions. Surge, heave, and pitch degrees of freedom are considered. Control surfaces are actuated using fluid power. Noisy sensors for wave height, acceleration, attitude, and rate are assumed. The objective is to minimize acceleration while maintaining the foils near trim depth and control deflections within cavitation limits. The relationship of horsepower capacity to performance is also sought.