Method for modeling long distance autonomous underwater vehicle

It is well known that the hydrodynamic model of autonomous underwater vehicle (AUV) is very important for system analysis, design and simulation, but the traditional model of AUV suffers from the following two shortcomings: (1) the local earth coordinate is selected as an inertial one, the model does not consider the curvature and rotation of the earth; (2) the geographic positional parameters, such as longitude and latitude, are not included in the model. Therefore such a model will result in a big position error and cannot be used for integrated navigation and control system simulation for a long distance AUV. In order to overcome the aforementioned problems, a hydrodynamic model for long distance AUV is proposed. In order to establish the hydrodynamic model of long distance AUV, the earth-centered inertial coordinates and earth-centered earth-fixed coordinates, navigation coordinates, body-fixed coordinates and velocity coordinates are selected. The hydrodynamic model consists of two parts. The first part is the six-degree-of-freedom dynamic equations in earth-centered inertial coordinates based on the theory of momentum and moment. The second part is the six-degree-of-freedom kinematic equations by coordinates transformations among earth-centered inertial coordinates, earth-centered earth-fixed coordinates, navigation coordinates and body-fixed coordinates. This model has been successfully used in integrated navigation and control system semi-physical simulation for long distance AUV, Simulation results show that this model has the following two distinguishing features: (1) Because the model is established in the earth-centered inertial coordinates, the navigation parameters, such as longitude and latitude, are included in the model, therefore the model is more suitable for global guidance system simulation for long distance AUV. (2) The model is suitable for long distance AUV integrated navigation and control system simulation and can be used for precision analysis and precision index assignment of the sensors of navigation and control system.