Study Of Longitudinal Motion Control System On SWATH

SWATH has a better seakeeping performance than traditional ships. But the trim counter rotating is always deduced, especially when ships are in high speed because of the small waterline areas. Furthermore, the 'MUNK' toque makes it easy to lose the stability, even lose the ability of navigation and commutation. In solving this problem, the application of fin stabilizer is a good way. The method of controlling the longitudinal motion of SWATH using LQG optimum is discussed.Domestic and oversea histories of anti-rolling measures and SWATH development are reviewed, and then the SWATH motion equations based on the longitudinal motion linear strip theory is introduced, and the relationship between the choice of fins and the stability of SWATH is discussed. Based on what are discussed above, the design and research about longitudinal motion control system combined with LQG optimum control theory are analyzed in detail, which are simulated by MATLAB. The principles in selecting weight matrix and the results of relevant simulation tell that the motion equations based on the LQG optimum control theory have very good dynamic performances. In addition, the theory of LQG quadratic gaussian optimum control is also discussed in application for the optimum design of this system. Since this method takes the random noise and random measuring noise in consideration, the control strategy developed is more practical in solving quadratic optimum control problems.With a lot of tests and simulation analyses from the weight matrix selection of quadratic optimum control design, the principles of selecting weight matrix are summed up. The quadratic optimum control design is object-independent, although the selection of weight matrix is longitudinal motion control systems oriented. So, when the weight matrix is hard to determine in the LQG quadratic optimum control, the principles developed to design weight matrix is also valuable for referencing.