Adaptive Path Control of Surface Ships in Restricted Waters

摘要

The feasibility and effectiveness of using an integrated system for the adaptive control of a surface ship along a prescribed path in restricted waters is investigated. The prescribed path is restricted to straight line segments which would extend between isolated turning maneuvers. The controller consists of four major components arranged in two loops: an inner or control loop and an outer or gain update loop. The inner loop consists of a Kalman state estimator and an optimal stochastic control law which would provide effective control when subjected to disturbances and measurement noise. The outer loop estimates the parameters of the system equations of motion to enable the controller to adapt itself for the changes in ship characteristics which take place due to changes in the ship operating condition and environment. The Brownian motion process is shown to be an effective model for bias disturbances in the design of the Kalman filter. A design criterion is proposed for the selection of the appropriate value of the diffusion coefficient to achieve the desired character of the disturbance model. A control loop designed using this approach is shown to perform very effectively with typical disturbances. The transient response of the control loop is, however, sensitive to variations in two of the coefficients in the equations of motion.