Application of nonlinear filter on the position estimation of dynamic positioned ship

In order to solve the problem of dynamic positioning ships when they lose the GPS signals during their operations, and cause drifting away from their setting points due to the deviant operation of the dynamic positioning system, this paper had designed a nonlinear filter which can use the history data of the ship to make real time estimating of the ship´s position. This enable the ship maintains its position near the operation point in a given period. When regain the GPS, it can return to normal operation quickly. In order to make the history data more accurately to the real time position, this paper compensated the history data by using its mean error to the setting point. At the end of this paper, there are the simulating curves of the designed nonlinear filter in the marine simulator system. Analyzing results show that there is an obvious improvement in estimating the real time position of the ship with the nonlinear filter relative to that without the nonlinear filter.