Nonlinear Output Feedback Control of Underwater Vehicle Propellers using Advance Speed Feedback

T.I. Fossen, M. Blanke

Publikation: Working paper/PreprintWorking paperForskning

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More accurate propeller shaft speed controllers can be designed by using nonlinear control theory. In this paper, an output feedback controller reconstructing the advance speed (speed of water going into the propeller) from vehicle speed measurements is derived. For this purpose a three-state model of propeller shaft speed, forward (surge) speed of the vehicle and axial inlet flow of the propeller is applied. A nonlinear observer in combination with an output feedback integral controller are derived by applying Lyapunov stability theory and exponential stability is proven. The output feedback controller minimizes thruster losses due to variations in propeller axial inlet flow which is a major problem when applying conventional vehicle-propeller control systems. The proposed controller is simulated for an underwater vehicle equipped with a single propeller. From the simulations it can be concluded that the advance speed can be estimated with good accuracy. In addition the output feedback integral controller shows good performance and robustness.
StatusUdgivet - 1999