Research On Dynamic Modeling And Control Of Underwater High-speed Vehicle

Underwater high-speeds vehicle breaks the velocity bottleneck of underwater movement with its low fluid drag and obtains super high underwater speed. It will become a new generation of high-speed underwater weapons to combat and intercept various land, sea and air military targets with its speed advantage, and with its long-range strike, high-speed, and concealment superior operational effectiveness to defeat the enemy. This paper takes the national defense basis research projects "Research on theory and related technology of underwater high-speeds movement" as background. The dynamic modeling and vertical motion control problems of underwater high-speeds vehicles are mainly studied. The main works are:The stress analysis and collate are completed for movement model of high speeds vehilce with rudders and without rudder by using rigid body dynamics principle and ship modeling theory. Especially, simulation and calculation of the planing forces produced in the tail of the vehicle are done to analyse its cause and process. Finally, a nonlinear dynamic model of the supercavity vehicle is established. It offers theory foundation for analyzing the dynamic characteristic and designing control system.Linearization is completed for nonlinear movement equations by introduced the small perturbation theory, then linear differential equations of the model with rudders and without rudders have been derived. For the model with rudders, this paper proposes that take the cavitator deflection and rudders deflection as control variables to establish its state-space expression, and for the model without rudders, this paper proposes that take the cavitator deflection and pitch angel and thrust vector deflection as control variables to establish its state-space expression. The controllability and observability are done for rudders control model and no rudders control model. Because of the complexity of underwater high-speeds, there are many uncertainties such as modeling error of the vehicle object, system parameters uncertainty or dynamic characteristics can not be fully identified and so on. So for the model with rudders, take cavitator deflection and rudders deflection as control variables, using robust pole assignment algorithm to design the controllor. The simulation results show that the method could effectively improve the model dynamic stability; For the model without rudders, take cavitator deflection and pitch angle and thrust vector deflection as control variables, firstly using LQR method to design the controllor for the vehicle, as the anti-interference capability of the LQR control system is weak, then H_∞mixed sensitivity method andμsynthesis method are used to design the cotrol system for the vehicle. The simulation results show that the system has stronger robustness.On the base of theoretical study of the dynamic characteristics and control strategies of the supercavity vehicle, presents hardware implementation technical difficulties and key issues on tactical control system of high-speeds underwater vehicle, then discusses the application of catastrophe theory in cavitation problems. Finally, analyzes and prospects the research focuses of supercavity problem.