Generic 6-DOF Added Mass Formulation for Arbitrary Underwater Vehicles based on Existing Semi-Empirical Methods

Abstract

The KTH Maritime Robotics Lab is developing a simulation framework for experimental autonomous underwater vehicles in MATLAB and Simulink. This project has developed a formulation for added mass of the vehicle, to be implemented in this simulation frame-work. The requirements of the solution is that it should require low computational power, be a general formulation applicable on arbitrarily shaped vehicles and be veri-fied against literature. Different existing methods and formulations for primitive bodies have been investigated, and combining these methods has resulted in a simplified but adequate method for calculating the added mass of arbitrarily shaped hulls and control surfaces, that is easy to implement in the existing simulation framework. The method has been verified by calculating added mass coefficients for two existing vehicles, and comparing the values to the coefficients already calculated for the vehicles in question. Some limitations have been identified, such as the interaction effects between compo-nents of the vehicle not being taken into account. To determine the extent of the errors due to this simplification and to fully validate and verify the model, future work in the form of CFD calculations or experiments on added mass measurements need to be con-ducted. There is also an uncertainty in the calculation of the coupled coefficients m26 and m35, and results on these coefficients should be handled with care.