Abstract:
Improving the performance of modular, low-cost autonomous underwater vehicles (AUVs) in such
applications as long-range oceanographic survey, autonomous docking, and shallow-water mine countermeasures
requires improving the vehicles' maneuvering precision and battery life. These goals
can be achieved through the improvement of the vehicle control system. A vehicle dynamics model
based on a combination of theory and empirical data would provide an efficient platform for vehicle
control system development, and an alternative to the typical trial-and-error method of vehicle
control system field tuning. As there exists no standard procedure for vehicle modeling in industry,
the simulation of each vehicle system represents a new challenge.
Developed by von Alt and associates at the Woods Hole Oceanographic Institute, the REMUS
AUV is a small, low-cost platform serving in a range of oceanographic applications. This thesis
describes the development and verification of a six degree of freedom, non-linear simulation model
for the REMUS vehicle, the first such model for this platform. In this model, the external forces
and moments resulting from hydrostatics, hydrodynamic lift and drag, added mass, and the control
inputs of the vehicle propeller and fins are all defined in terms of vehicle coefficients. This thesis
describes the derivation of these coefficients in detail. The equations determining the coefficients,
as well as those describing the vehicle rigid-body dynamics, are left in non-linear form. to better
simulate the inherently non-linear behavior of the vehicle. Simulation of the vehicle motion is
achieved through numeric integration of the equations of motion. The simulator output is then
checked against vehicle dynamics data collected in experiments performed at sea. The simulator is
shown to accurately model the motion of the vehicle.
