Design and initial in-water testing of advanced non-linear control algorithms onto an Unmanned Underwater Vehicle (UUV)

UUVs equipped with high-level control software have a variety of potential applications for Anti-Terrorism/Force Protection (ATFP) objectives. Desirable vehicle control capabilities include the ability to drive at very low, controllable speeds, the ability to maintain a set distance and attitude (pitch and roll) relative to some surface for optimal sensor (both sonar and video) effectiveness, and the ability for the operator to intervene to change the mission activities. Moreover, a vehicle capable of rotating in place or having a fraction of a meter turning radius is needed to conduct the mission. The present state-of-art vehicles are not maneuverable enough to successfully accomplish most of these tasks. The novel controllers are expected to be nonlinear due to the fact that the vehicle is translating at nonzero attitude or translating in a direction different from that of the surface. Non-linear controller that compensates for non-linear forces (such as drag, buoyancy/gravity) was designed, installed onto the UUV test-bed, and in-water tested. The structure of a controller is hierarchical such that an "inner loop" non-linear controller (outputs the appropriate thrust values) is the same for all mission scenarios while an appropriate "outer-loop" nonlinear controller is used based on what mission or part of the mission is desired.