Route Planning Research Based On Gravity Information

Inertial navigation system is the main navigation method of underwater vehicle navigation positioning system, but the inertial navigation system error accumulates over time. It’s difficult to ensure the positioning precision after long time work. So other navigation mode is needed to aid inertial navigation. Gravity field information can be applied to water diving device aided navigation system for its stable nature and the characteristic of independent and passive access. Path planning is one of the key technologies in the gravity aided inertial navigation. It relates to the matching precision of gravity aided navigation system. Therefore, in order to ensure the veracity of the positioning information of underwater gravity aided navigation, it’s urgent to solve gravity aided navigation route planning problem.For the gravity matching aided navigation route planning problem, the preferred path planning based on the start and stop is analyzed in the paper to improve the match positioning accuracy. Due to the close relationship of matching positioning precise and sailing area, it’s necessary to make assessment of matching effect of the sailing area. First, the selection of the matching area is introduced. In the paper, in the basis of the traditional matching area selection method, isotropic coefficient is adopted to measure the direction of matching area. Comprehensive characteristic parameter is constructed by traditional parameters and isotropic coefficient through the analytic hierarchy process(AHP) to select the matching area. Route planning is conducted after the matching area selection. Based on the classic A * algorithm, the improvements are carried out in two steps: gravity characteristic parameter is added to the evaluation function and weight coefficient and search step length are dynamic programmed, making A * algorithm is more suitable for gravity aided inertial navigation route planning. The paper mainly includes the following work:1) Three traditional matching area selection methods are analyzed: the threshold value method, SPSS regression analysis method, analytic hierarchy process(AHP). Through comparison analysis and simulation, isotropic coefficient is introduced to measure the sensitivity of the matching area to direction thus making up for the disadvantage of traditional method.2) Characteristic parameters of the gravity field are analyzed: the gravity field variationcoefficient and kurtosis coefficient, skewness coefficient and isotropic coefficient are combined to build a comprehensive characteristic parameter by analytic hierarchy process(AHP). The matching area selected by the threshold of comprehensive characteristic parameters can improve the accuracy of the matching area selection.3) The principle and application of the A * algorithm is analyzed. Combined with the matching area, comprehensive characteristic parameter is introduced in the estimate function of A * algorithm to make that the evaluation index of A * algorithm not only contains the distance, but contains gravity characteristics. The simulation shows that the route planning obtained by the improved A * algorithm can get good matching effects and timely correction of inertial navigation..