Dynamic modeling of Remotely Operated Underwater Vehicles (ROVs) is discussed, including special issues uncovered in the literature. A general purpose ROV simulator (SOL) was developed to be used as a design tool. Here an actual four propeller ROV is considered. A discrete-time version of a recently developed variable structure controller (I/O VS-MRAC) is applied to obtain high performance position control, outperforming conventional controllers as shown by simulations.
Remotely Operated Underwater Vehicles (ROV)play an important role in off-shore oil operations. They are also being increasingly used in a number of important applications Although Remotely Operated underwater Vehicles (ROVs) have been applied for quite a longtime, their "operation still remains a difficult task which is time-consuming and demands much of the pilot Is attention. The main reason for this difficulty is the complexity of the ROV dynamic behavior. The degrees of freedom, highly interacting in general, have to be simultaneously controlled by the pilot by "means of "a coordinated handling of the thrusters actions. However, the operation can be considerably simplified by the automatic control of the ROV positions the, lower level of an hierarchical system where, the pilot would take care of higher level functions (mission planning, obstacle avoidance, guidance, etc.). In the case ·of autonomous vehicles, a topic of sharply increasing interest, this kind of control system is even more important. Designing high quality automatic controllers for an ROV is not an easy task. The dynamic response provided by such controllers should satisfy simultaneously a set of strict specifications in terms of speed, precision, overshoot and interactions among the controlled coordinates. The choice of the control scheme should also take into account the environmental disturbances, such. as sea current and turbulence. near subsea structures, normally. acting on the ROV.