Study On Nonlinear Motion Modeling And Control Of High-Speed Foil-Assisted Boat

Foil-assisted boat becomes sensitive to external disturbances, such as wind, wave and etc, during its transition from hull-borne mode to foil-borne mode. Therefore, special control system is required to ensure its seaworthness. Although some researchers have applied conventional control theories to its controller design, it is still a problem to make full use of the new results of control theory to design the controller. And furthermore, the previous designs cannot keep effective throughout the overall operating overlope. Therefore, the mathematical model is firstly proposed. Then, this paper designs its controller by use of newly developed control methods, and also meet its special requirement. Regarding motion modeling and control of foil-assisted boat, the main research results are presented as follows.Mathematical modeling is not only important to testify its controller design, but also one of the key technologies to develop the shiphandling simulator for foil-assisted boat. Therefore, through fluid analysis, the mathematical model is established of heave and pitch motions in waves. The calculations of the relevant parameters are detailed. In consideration of large fluctuations of some boat's parameters during different operating mode, the method of fitting the curves of hull sections are proposed to calculate the parameters on line. To validate the effectiveness of the modeling process, based on such a boat, "HC200B-A1", simulation researches are carried out, by use of Matlab's Simulink Toolbox. It's shown that the simulation results agree with well the experimental data and also marine practice, and the model herein is competent and reliable in the future research.To design the boat's attitude controller, firstly, a novel P-D (proportional-derivative) control scheme is addressed with controlled fore and aft flaps. The traditional P-D controller requires that 8 feedback gains be chosen manually, while herein only 4 parameters. The key idea lies in the introduction of virtual control input, which is distributed between fore and aft flaps. To further improve the performance of the attitude controller, the newly developed techniques of controller design are studied. Therefore the state space model is proposed through Jacobian linearization of the nonlinear model around its equilibrium. All the partial derivatives contained in the model are detailed. Based on the linear model, state-feedback H_∞ technique is thenutilized to design the attitude controller, whose performance index takes account of the boat's exogenous disturbances. Simulation researches show that//~ attitude controller's performance is better than linear quadratic regulator (LQR) scheme. Moreover, output-feedback H~ control technique is also employed, which is featured by not only the consideration of exogenous disturbances but also the need of only partially-known information from the boat's states. Based on "HC200B-A1", simulation researches have demonstrated the efficiency of the designs.However, only in the vicinity of its design points are the aforementioned controller designs effective. However, it is found that attitude control strategies with fuzzy gain scheduling scheme are successful to overcome this drawback. Therefore, fuzzy controller design is studied based on T-S fuzzy model. (1) For nonlinear H~ control problem, a less conservative LMI-based //- fuzzy controller via T-S fuzzy model is proposed, and applied to attitude control for foil-assisted boat. The proposed /f~ fuzzy controller can guarantee that the closed-loop system is UUB (uniformly ultimately bounded) with prescribed H<~ control performance. (2) For nonlinear system with parametric uncertainties, a novel robust fuzzy controller design with much less conservetiveness is proposed. The controller can guarantee that the fuzzy system is asymptotically stable at its equalibrium. (3) Robust fuzzy 77- output feedback controller is also proposed for a class of nonlinear system in the presence of both parametric uncertainties and exogenous disturbances, by use of DPDC (dynamical parallel distributed compensation) scheme. Robust fuzzy //? controller can guarantee the asymptotical stability of T-S fuzzy system and //? control performance. Then, T-S fuzzy model for foil-assisted boat is proposed. And these fuzzy controller design schemes are applied to foil-assisted boat. Simulation reseaches have shown that the proposed schemes are effective throughout its operating range.