A low-speed control module for a streamlined AUV

Streamlined autonomous underwater vehicles (AUVs) are typically designed to operate at a nominal speed. Control surfaces are sized to meet control requirements near this operating condition. Occasionally, the need arises for a vehicle to operate at a lower speed, for example, to perform an inspection task. Because hydrodynamic forces and moments decrease quadratically with speed, there is generally some minimum speed below which a streamlined AUV can not operate. If the vehicle is slightly buoyant, for example, it may be incapable of generating sufficient down-force to maintain depth. This paper describes the use of a moving mass actuator (MMA) module to augment control of an existing streamlined AUV in order to obtain a lower minimum operating speed. In some scenarios, as described in the paper, the MMA may be combined with a fixed wing to generate additional lift. The results of analysis include sizing guidelines for control surfaces and MMA modules and a technique for estimating the minimum controllable speed.