Research On Ship Autopilot Electric Drive Control Technology

Since the beginning of the new century,marine situation of China has become increasingly tense with the change of the world pattern.Research and development of high-performance naval vessels has become an urgent need for China to build a marine power.It is particularly important to reform technology of vessel equipment and upgrade servo system.This paper adapts to the development trend of the whole electric propulsion ship,and in order to solve the problems existing in hydraulic drive system of ship autopilot at present,a kind of electric drive servo system is designed to realize rudder position servo control and ensure that the system has good anti-interference performance.The main work of this paper is as follows:Firstly,the realization scheme,control strategy and related technology of the electric drive servo system were studied in this paper.According to the parameter and performance index of the rudder equipped on the target ship,the load torque at the end of the rudder shaft was analyzed,and the driving power required by the servo system was calculated.The technical characteristics of ship autopilot electric drive servo system was summarized,and the rotating electric machine drive scheme coaxial connected with reducer and the electric cylinder drive scheme was compared.A design scheme of the equivalent physical prototype of autopilot drive servo system was given according to the idea of equal-scaling model,and the related equipment selection was completed.Secondly,the mathematic model of autopilot electric servo system was given.According to engineering design method,the design process of closed-loop PID control strategy was given.A sliding-mode control strategy was proposed because of the large load disturbance on the rudder shaft.Aiming at the problem of sliding mode chattering,the relationship between system robustness and chattering was analyzed,and an improved variable gain exponential approaching law was designed.The switching gain was adjusted adaptively according to the position deviation and the switching function.The robustness of the system can be maintained while the degree of chattering was effectively suppressed.Simulation results in MATLAB environment showed that the system using sliding mode control strategy had better control effect and anti-interference performance than that using PID control strategy.Then,the hardware design of the controller was completed according to the servo system scheme,including the master chip minimum system of TMS320F28335,digital-analog conversion circuit of torque signal,encoder output signal conditioning circuit and serial communication circuit.In the CCS development environment,the system controller software design was completed.The control strategy is implemented by software program.At the same time,a data communication message transmission format was given,which realized the real-time upload of position,speed and given signal.Based on the C++ language,the interface program of the host computer software was designed,and the autopilot position reference transmission as well as the function of data display and monitor was implemented.Finally,the ship autopilot electric drive servo system was completed.DSP controller and other related hardware,host computer software interface,and the function of data communication was tested.The step response test and sinusoidal tracking test of the equivalent physical prototype of autopilot drive servo system proved that the servo system was feasible.