Modelling and LQG/LTR Control of a Propelled AUV in Longitudinal Dynamic

The development of underwater vehicles considers main areas of modelling, navigation, guidance and control. The autonomous underwater vehicles have been modified in order to improve the maneuverability and to be applied in local inspection tasks, such as remotely operated vehicles. The current paper investigates the modelling and control of an AUV composed of four propellers, stabilizing fins and without control surfaces. The modelling is developed following the slender body theory, obtaining the longitudinal hydrodynamic coefficients. The LQG/LTR robust control approach is applied to control the surge and pitch rate dynamics. The pitch attitude dynamics in uncontrollable directly by a centralized controller, then a PID in cascade structure is proposed to tack this problem. The results achieve the desired performance in rising and diving maneuvers.