| Underwater Glider(UG)has the advantages of low manufacturing cost and long endurance,and have been widely used in the field of ocean phenomenon observation.However,the UG has insufficient power,and the influence of ocean current on the motion state of UG is decisive.The attitude control of UG with ocean current interference is a difficult problem.Ocean phenomena span a large space and time scale,so it is impossible to accurately describe ocean phenomena in multidimensional and three-dimensional by relying only on a single set of UG,so it is necessary to cooperate with other underwater observation platforms including gliders for observation.UG cannot transmit position information when underwater,so it is an urgent problem to improve the prediction accuracy of water position.In this thesis,the hybrid drive UG "Petrel-II" is taken as the research object.Based on the analysis of the influence of instantaneous ocean current on the motion state of UG,a fuzzy active disturbance rejection controller is designed,which improves the anti-interference ability of UG attitude control compared with the traditional controller.At the same time,considering the buoyancy loss and the influence of ocean current,the depthaveraged currents algorithm is adopted to improve the prediction algorithm of UG outlet position,and thus improve the prediction accuracy of UG outlet position.The main research achievements and innovations of this thesis are as follows:1.Aiming at the modeling problem of UG with ocean current,the ocean current mathematical modeling is carried out and it is integrated into Euler angular coordinate transformation relation and momentum equation.The six-degree-of-freedom kinematics and dynamics equations of UG with ocean current term are derived,and the actual sea trial data of "Petrel-II" is used to verify the mathematical model.Then three typical motion modes of UG are simulated.In order to analyze the influence of ocean current on UG,inverse ocean current,vertical ocean current and lateral ocean current were added respectively to carry out motion simulation,and the variation degree of various motion parameters of UG when facing currents in different directions was summarized,which provided mathematical basis for the subsequent work.2.A fuzzy adaptive Linear Active Disturbance Rejection Controller(LADRC)is designed for pitch angle and depth of UG.Then three simulation conditions are designed:fixed expected input,changing expected input and adding current interference.The fuzzy adaptive LADRC controller is compared with fuzzy adaptive PID controller and traditional PID controller in the simulation experiment.The simulation results show that the fuzzy adaptive LADRC controller has the advantages of short response time,excellent adaptive ability and strong anti-interference ability in the pitch angle and depth control of UG.3.In order to improve the prediction accuracy of the outlet position of UG,the effect of buoyancy loss and sea current on it is simulated and analyzed.In view of the above situation,this paper introduces and updates the deep mean flow algorithm to make it adapt to the actual scene when adding propeller.Three sections were intercepted from 95 section data measured in sea trials,and each section had 10 zigzag motion cycles to verify the UG outlet position prediction.The experimental results show that the algorithm can significantly improve the accuracy of UG outlet position prediction.In this paper,a relatively accurate UG mathematical model is established,and the relative advantages of the fuzzy adaptive LADRC controller are analyzed in attitude control and depth control.Through the actual UG data,it is verified that the improved deep mean flow algorithm can significantly improve the prediction of the water position of UG,which provides ideas for the subsequent optimization of UG under the actual environmental interference. |
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