Design Of Dynamic Positioning System Control Strategy For Dredger

With the increase of the dredging amount,the demand of the dredging efficiency is gradually improved,more and more dredgers begin to adapt DP(Dynamic Positioni-ng) system.It's a closed-loop feedback control system,compared with the traditional positioning method,DP system can position by its own generated thrust without any external devices,it can work under sea in any depth,and it has a rapid response on t-he external environmental change so that it can finish special task such as moving in a fixed track. With the support of jiangsu province high technology research proje-ct,the paper take "Design of Dynamic Positioning System Control Strategy for Dred-ger" as a dissertation research subject.According to the particularity of DP system ofdredger,the paper analyze the thrusting force allocation problems systematically,it hasexplicit engineering application background and practical value, the main contribution is as follows:According to the particularity of the DP system of trailing suction hopper dredg-er,a selection of propellers is proposed and the reasons are analyzed.Two different t-hruster configurations are provided for trailing suction hopper dredger,focusing on theanalysis of the problem of thrust allocation in the two configurations.In the first co-nfiguration,the dredger is equipped with one bow thruster,two main thrusters and tw-o rudders,the thrust allocation strategy is designed forthe eight modes of trailing suct-ion hopper dredger according to the thrust command given by the control system,an-d the thrust generated by the thrusters is calculated respectively.In the second config-uration,the dredger is equipped with four azimuthing thrusters,the thrust allocation ta-rget of the second propulsion configuration is to minimize energy consumption,also consider the limits of the propeller thrust,singular structure and other factors.The thru-st optimal allocation is based on the sequential quadratic programming method accor-ding to the thrust command generated by the control system.On this basis,a evaluation method to analyze the capability of the DP system ofthe trailing suction hopper dredger is introduced,which is called dynamicpositioning c-apability plot.Using DPCAP software,the model of DP system of the trailing suctionhopper dredger is established and the dynamic positioning capability plots of the twodifferent propeller configurations are analyzed.The two different configuration of thrus -t allocation are simulated using MATLAB,the control signals are obtained and analy-zed.In the paper,the operating process of eight modes of trailing suction hopper dre-dger DP system is introduced,including how to operate in the eight modesand how t-o examine all states of dredger.Part of the research results of the paper has been applied in a trailing suction h-opper dredger,recognition and praise is obtained by the relevant leaders of shipyard.