Global Output Feedback Control ofDynamically Positioned Surface Vessels: An Adaptive ControlApproach


Unmanned surface vessels have become an important tool in marineapplications, mostly related to offshore oil industry. As a result,the development of automatic ship control systems has been a topicof considerable interest over the past decade. A dynamicallypositioned ship is a ship system where its three degrees-of-freedom(i.e., surge, sway, and yaw) are controlled via thrusters andpropellers aft of the ship. In this paper, we consider the outputfeedback control problem for dynamically positioned surface vesselswhen uncertainties related to the system parameters are present.Specifically, by applying Lyapunov techniques, we design anonlinear model based adaptive output feedback controller thatachieves global asymptotic tracking and compensates for theparametric uncertainties associated with nonlinear ship dynamicsdespite the lack of velocity measurements. Simulation results areincluded to illustrate the performance of the proposed controllaw.

Simulation Results

Fig.1 Position Tracking Errors

Fig.2 Control Torque Inputs

Fig.3 Parameter Estimates for MatrixM

Fig.4 Parameter Estimates for MatrixD


For more information concerning this research, please refer tothe following publication:

Y. Fang, E. Zergeroglu, M. S. de Queiroz and D. M. Dawson, "Global Output Feedback Control ofDynamically Positioned Surface Vessels: An Adaptive ControlApproach", Proc. of the American Control Conference, June,2001, pp. 3109-3114.

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