Fuzzy Adaptive Control And Its Application For Ship Steering

Since Zadeh, who was the professor of University of California in America, founded fuzzy theory in 1965,fuzzy control develops quickly because fuzzy logic provides a method based on language rules and reasoning. It is an important embranchment of intelligent control. At present ,fuzzy control develops towards adaptive control and self-learning control. The adaptive controllers make the parameters and rules regulate, modify and perfect constantly, so the best performance of the control system can be obtained.The motion of ship is nonlinear. The operating machine has nonlinearity such as dead zone and relay. The dynamic characteristic of ship is related to the conditions of sail such as wind, wave, flow and so on. The manipulation of ship is a very complicated problem.The autopilot is the key equipment of the ship. PID rudder is the first generation. Its algorithm is simple. The physical meaning of the parameter is obvious. The effect of control is creditable, but the precision and adaptability are not so good. Adaptive control does well in the precision and fuel efficiency, but the cost is high. The performance of control is hard to guarantee.In this paper, the schemes of several fuzzy adaptive controllers are summarized. The fuzzy model reference adaptive control system for ship steering based on linear model and nonlinear model is constructed. With the help of simulink, fuzzy logic box provided by Matlab, s-functions are written in C and M files. The output plots of heading and rudder angle can be obtained. The experiments are performed to test the disturbance rejection properties of the fuzzy model reference adaptive control compared with fuzzy control. The simulation results show that the fuzzy model reference adaptive control has more advantages. Next, A self-learning algorithm is put forward. Thisalgorithm comes from the repeated control of the robot. It is an attempt to apply this algorithm to ship steering. The project of fuzzy self-learning control is written in the integrated development environment of C++ Builder 5. The simulations are performed for the linear and the nonlinear process. The results suggest the algorithm is correct. It is attempt to realize fuzzy control for the ship steering in microcomputer in regard to the application of fuzzy control in the last chapter of the paper. The program of fuzzy control is written in assemble language in the developing system given by the corporation of tsinghua tongfang .The paper is based on the project of National Natural Science Foundation "the intelligent control system of ship on bumping and avoiding bumping"and "the study based on the impulsion response of light duty configuration, control and experiment method of high speed ship". The fuzzy adaptive control is applied to ship steering. It is significant to improve automation technology of ship in china.