Research On Safety Navigation Control Strategy Method For Air Cushion Vehicle

As a kind of high performance ship,the air cushion vehicles(ACV)attracts attentions of nearly all military superpowers in the world due to amphibious and fast features.The hull structure,the sailing environment and status of the ACV are significantly different from the ordinary ship,for example,the existence of the cushion system makes the water dynamic and aerodynamic have stronger nonlinear and uncertainty then the ordinary ship.The small navigation resistance and poor stability often make the ACV occur sideslip phenomenon,to be exposure in the dangerous sailing condition and dangerous situation developing rapidly,and leading to capsize accident easily.Therefore,it has important military value and civil value to solve the control problem of ACV navigation safety.Around the theme of ACV safety sailing,the in-depth study is carried out from the view of ACV mathematic modeling and analysis,the stable trajectory angle control,the establishment of sailing safety bound and emergency control in this dissertation.The main contents of dissertation are as follows:Firstly,in order to meet the needs of safety sailing,the six degrees of freedom mathematic model is established for ACV,focusing on the mathematical model of cushion system and the wave resistance model.The simulation and analysis for the ACV maneuverability in the normal state and fault state is carried out,it lays a foundation for trajectory angle control and emergency control.Secondly,aiming at the underactuated ACV safety sailing trajectory angle control problem,the concept of the trajectory angle indirect input is proposed.Based on the desired heading update strategy according to the sideslip angle information,a finite time convergence terminal sliding mode ACV safety sailing trajectory angle control method is proposed to transform the trajectory angle control to the heading control problem,the stable and fast tracking to the desired trajectory angle is realized,and the large sideslip angle which leads to unsafty is avoided.Lyapunov stability theory is applied to prove the stability of the system.Effectiveness of the proposed control method is verified by simulation.Then,to sovle the fully actuated ACV trajectory angle tracking control problem,the multi control surface strategy is proposed.The forces(torques)coordination distribution module is introduced,and the fore nozzle is used to counteract the sideslip angle,and the air rudder is used to produce rotary torque and track the desired trajectory angle.The terminal sliding mode controller is designed to realize the stable and fast tracking to the desired trajectory angle and avoid the sideslip angle.The Lyapunov stability theory proves the stability of the system,and simulation is carried out to verify the feasibility and effectiveness.Furthermore,according to the ACV trajectory angle control working mode,the main factors which lead to closed-loop system instability is commented,the state prediction method of losing steady for ACV is proposed by obtaining the closed-loop system security clearance,based on BP neural network and Lyapunov stability theory.Lyapunov stability theory is used to get the stability judgement,the BP neural network is used to confirm the security clearance.The obtained ACV safety clearance judgement forecast model can check the stability of the ACV current motion parameters.And the rationality is verified based on the ship test data.Finally,for the emergency situation when the ACV motion parameters exceed the corresponding security clearances,an emergency optimal control method is proposed to make motion parameters return to the system security clearance based on optimal control theory.The simulations of safety control problems for heading,trim and heel show that,in the bad sea condition and high speed,emergency optimal control method can ensure the ACV in safty sailing state.