Fuzzy/Kalman Hierarchical Horizontal Motion Control of Underactuated ROVs

A new closed loop fuzzy motion control system including on-line Kalman’s filter (KF) for the twodimensional motion of underactuated and underwater Remotely Operated Vehicle (ROV) is presented. Since thesway force is unactuated, new continuous and discrete time models are developed using a polar transformation. Anew hierarchical control architecture is developed, where the high level fuzzy guidance controller generates thesurge speed and the yaw rate needed to achieve the objective of planar motion, while the low level controller givesthe thruster surge force and the yaw torque control signals. The Fuzzy controller ensures robustness with respectto uncertainties due to the marine environment, forward surge speed and saturation of the control signals. AlsoLyapunov’s stability of the motion errors is proved based on the properties of the fuzzy maps. If InertialMeasurement Unit data (IMU) is employed for the feedback directly, aleatory noises due to accelerometers andgyros damage the performances of the motion control. These noises denote a kind of non parametric uncertaintywhich perturbs the model of the ROV. Therefore a KF is inserted in the feedback of the control system tocompensate for the above uncertainties and estimate the feedback signals with more precision