Research On Sonobuoy Area Dynamic Positioning

Sonobuoys' layout is relatively simple, and the measurement array is consisted of many sonobuoys, with highly measurement accuracy. And it also can compensate for the fixed sonar' s direction blind spots without the interference of the ship nosie. It is an important underwater detection equipment. The motorized sonobuoy which compensate for the shortcomings that currently sonobuoy must be moored to the seabed to keep its position and it's difficult to be laid and recovered,and the measurement array can not evolve based on the need of sea test after laying the array . The motorized sonar buoys could hold its position automatically and effectively simplify the sonobuoy's laying recovery, shorten the buoy array layout measuring time and improve the efficiency of sea trials. The motorized sonobuoy controller is designed based on ideas of green dynamic positioning and model predictive control. It can effectively reduce the sonobuoy's power when performing holding position and prolong the working hours of sonobuoys. To achieve these goals, this paper has done the following research areas:At first, this paper completed designing the motorized sonobuoy. It is the basis for future research work. To optimize the hull of sonobuoy lines, proposed four kinds of improved lines,used computational fluid dynamics method and calculated the resistance of the four lines. And finally found a line of the least resistance buoy housing. After the completion of the hull design, this paper optimized various parts of sonobuoys to improve the sonobuoys' initial metacentric height, selected suitable hardware of the sonobuoy control system, designed the related circuit, compared the commonly course measurement methods, and finally chose the MTi-G which had moderate price and good performance to measure the buoy heading. After the design is complete, checked the speedability ,stability and endurance of sonobuoysSecondly,combing the motorized sonobuoy's structural characteristics and reference ship modeling process,this paper established six degrees of freedom model of sonobuoys. Based on the characteristics of the motorized sonobuoy, ignored heave and roll, and finally simplified sonobuoy's four degrees of freedom model. In the smaller pitch angle of the premise, this paper further simplified its four degrees of freedom model and decouple the pitch and the other three DOF. Finally the paper presented the single degree of freedom pitch model in the vertical plane and three degrees of freedom motion model in the horizontal plane.Drifting buoy position was mainly affected by waves and currents,so the waves and currents model were bulit. Based on the reason for the pitch of sonobuoys, this paper designed the pitch PD controller, and carried out the simulation.Thirdly, this paper integrated the advantages of GreenDP and requirement of regional positioning and proposed the control strategy with advantages of meeting the requirements and saving energy. The classification and principle of model predictive control were introduced in detail. This paper used the method of Taylor expansion to expand the predictive index function to design the controller. Then carried out the simulation experiments which was under the currents disturbance. Experiments showed that the controller could hold the position of the sonobuyo effectively and smoothly.Finally, in the lake test, direct tests of the sonobuoy was carried out ,and the result showed the design of the sonobuyo is reasonable. According to the actual situation, three times regional position keeping test were carried out ,and the tests are successful.