Adaptive/integral actions for 6-DOF control of AUVs

In this paper the control of Autonomous Underwater Vehicles in 6 degrees of freedom is analyzed in a comparison study among several controllers. At steady state the vehicle needs to compensate for two dynamic effects, the ocean current and the restoring forces; the appropriateness of the adaptive/integral action designed with respect to those persistent effects is discussed. Moreover, for each controller an adaptive/integral PD+gravity-compensation-like version is derived and eventually, modified so as to achieve null steady state error under modeling uncertainty and presence of ocean current. Numerical simulations are presented to better illustrate the controllers' behavior.