Dynamic Analysis Of Underwater Vehicles Based On Differential Geometry Theory

Underwater vehicles as a new type of underwater reconnaissance platform, has agreat development prospect in the field of military and civilian. In underwater vehicledynamics analysis, the vehicles and the surrounding fluid are treated as a mechanicalsystem when they are analyzed. The vehicles complete the appropriate motionthrough the interaction with the fluid in the process of movement. The vehicles, withthe surrounding fluid, form a strong coupling nonlinear mechanical system due to thecomplicated interaction mechanism with the damping fluid.Based on the previous studies of the research group, with the introduction ofdifferential geometry method and the viewpoint of energy, the underwater vehiclesystem is analyzed and the unified geometric dynamics model of underwater vehicleis obtained. The hybrid underwater gliders and vectored thrust underwaterautonomous vehicle are analyzed. Through the specific analysis of the underwatervehicle system, the system property is obtained. Then the specific property issubstituted into the unified geometric underwater vehicle dynamics model.Underwater vehicle space kinematics and dynamics numerical simulation in sixdegrees freedom are analyzed. Through the simulation analysis and comparison oflake sea trial test, the unified geometric underwater vehicle dynamics model isverified. This provides the dynamic geometry model framework for the controlsystem based on differential geometry theory in the future research.The following contributions have been derived：1. By analyzing the characteristics of the underwater vehicle moving in the fluidcircumstance, from the viewpoint of energy, the dynamic equation of underwatervehicle is deduced. According to the characteristics of the special kind of mechanismsystem, Riemannian metric is introduced to represent the underwater vehicle massmatrix. Then through the derivation of the dynamic geometric model, the dynamicunified model for underwater vehicle is obtained.2. Based on analyzing the system of hybrid underwater glider, the simplifiedsystem model is obtained. Then the simplified model is analyzed in the unifiedgeometric underwater vehicle dynamics model. The model is simulated in the way of numerical simulation. By comparison with the sea trials, the results of numericalsimulation and the unified model are verified.3. Through analyzing the system of vectored thrust underwater autonomous vehicle,a simplified system model is obtained. Then the simplified model is substitute into theunified geometric underwater vehicle dynamics model. The model is simulated in theway of numerical simulation. By comparison with the sea trials, the results ofnumerical simulation and the unified model are verified.