Research On Course And Cushion Pressure Control Of Air Cushion Vehicle By Fuzzy Sliding Mode Control Method

As a representative of high-performance ships,the air cushion vehicle(ACV)has the advantages of strong adaptability to various terrains and fast sailing speed.However,due to its special navigation mechanism,there are inherent defects in maneuverability,poor safety,and unstable air cushion during navigation.Therefore,in order to ensure the maneuverability and safety of the ACV,it is necessary to control the track direction on the horizontal plane and control the cushion pressure on the vertical plane.According to the characteristics of the ACV being affected by environmental disturbance,large model uncertainty and obvious nonlinearity,the fuzzy sliding mode algorithm is chosen to design the controller,and the high-speed safe navigation of the ACV is guaranteed from the perspective of motion control.The main research contents are as follows:First,establish a mathematical model of the ACV movement,study the movement mechanism of the ACV,and lay the foundation for the controller design.Only in a reasonable model that conforms to the characteristics of real ships,the research on motion control technology has practical application significance.First,establish a fixed coordinate system and a motion coordinate system.Secondly,through the analysis of the ACV,its kinematic model is established.At the same time,block modeling is used to model the aerodynamics,hydrodynamics and control surfaces to establish a dynamic model.Finally,the mathematical model of the six-degree-of-freedom motion of the ACV was obtained.In addition,an environmental model including sea breeze and waves was established.Finally,the simulation model is used to verify that the established model is in line with the actual ship characteristics.Second,due to its special navigation mechanism,ACV is highly susceptible to changes in heading due to external environmental disturbances.Therefore,it is necessary to study and design the heading control method of the ACV.In this paper,the fuzzy sliding mode method is used to realize the heading control of the ACV.Firstly,the principle of sliding mode control is introduced,including its basic concept and mathematical description,controller design process,derivation of control law and stability judgment.Secondly,the ordinary sliding mode controller is established,and through the simulation test of the simple system,it shows that there is a large chattering in the control process.On this basis,the main reasons and solutions for the chattering are analyzed,and the fuzzy method is combined with the sliding mode.Finally,the common sliding mode controller and the fuzzy sliding mode controller are usedrespectively,and the ACV model is used to test the heading simulation in the windless and windy conditions respectively,and the effectiveness of the designed fuzzy sliding mode algorithm is proved.Thirdly,in order to improve the safety and maneuverability of the ACV in the high-level safety navigation control system,the driver’s operation control burden is reduced and the control method of the ACV’s track is controlled.In this paper,the improved integral line-of-sight(ILOS)is combined with the designed heading controller to realize the ACV course control.Firstly,the closed-loop guidance law is studied.The deviation guidance law and the line-of-sight(LOS)are introduced.According to the ACV track,the track deviation guidance law and the improved ILOS guidance law are designed according to the control requirements.Secondly,on this basis,the control strategy of the ACV course control is analyzed,and the method of determining the expected path,the calculation method of the track direction and the guidance law when the path is switched are given.Thirdly,according to the direct method control strategy,an ACV course control system based on closed-loop guidance of track deviation is designed.At the same time,according to the control idea of indirect method,a layered control structure is adopted to design an ACV course control system based on improved ILOS guidance law.Finally,the simulation comparison experiments were carried out on the two control systems under different environments.Fourth,the cushioning system is the key to the ACV,which fundamentally determines its maneuverability and safety.In order to reduce the bump in the direction of the hovering of the ACV,that is,the "cobblestone effect",the research and design of the cushion pressure control method for the ACV is carried out.Firstly,the pressure-flow formula of the cushioning booster fan,the air cushion volume change rate and the apron discharge flow is solved,and the mathematical model of the cushion system is established.Secondly,for its control needs,the sliding mode control method is selected to control the speed of the booster fan.Thirdly,the ordinary sliding mode controller is designed,and the adaptive fuzzy sliding mode controller is designed based on the universal approximation principle of the fuzzy method.Finally,design a simulation test.The common sliding mode controller and the adaptive fuzzy sliding mode controller are used respectively,and the ACV model is used to carry out the simulation test of the padding pressure control in the windless and windy conditions.