numerical investigation of dynamic stability of an auv

in order to determine the stability of underwater robots, their governing differential equations of motion in vertical and horizontal planes should be investigated. for horizontal plane stability, using routh stability criterion, four hydrodynamic coefficients, including derivatives of the lateral force and vertical moment with respect to sway and angular velocity are required. these coefficients are usually measured in a towing tank with rotating arm experimental facilities. in present work, these coefficients were calculated for an auv, using computational fluid dynamics. towing of the model, with various drift angles, in a towing tank and also rotation of the model in a rotating arm are simulated numerically, to obtain the required coefficients. the coefficients were then used to investigate the stability of the robot in horizontal plane and to determine the effect of control surfaces on the robot's stability.