Application Of Reverse Navigation Algorithm In Initial Alignment And Its System Implementation

This article is based on the FOG Strapdown Inertial Navigation System. As the SINS will not be affected by the limit of geographical, time and weather, it has the advantages of independent and concealment and can provide the navigation information timely. So it's widely used in military and civil affairs. As the key technology of SINS, the initial alignment technology indicators include accuracy and rapidity. Yet, they are inter-constraint in the self-alignment of SINS. Therefore, the study on how to reduce the time of the initial alignment while keeping up the accuracy has many practical implications.In this article, the author studies the basic theories of SINS, including its work, error equations and initial alignment technology, and also infers the related formulas. The paper focuses on the theory study on reverse navigation algorithm, aimed at reduce the time of the initial alignment without decrease the precision. The so-called reverse navigation algorithm,that is to say, if the navigation computer of SINS has sufficient memory capacities and serious computational power, the output of inertial device(including the fiber optic gyros and accelerometers)can be stored and treated as a set of time series. In addition to the conventional forward process, it can be also processed reversely. The paper derives the formulation related to the reverse navigation algorithm and obtains the relevant conclusions.Through the forward process and back process repeatedly, the analysis accuracy may be improved. If it's used in the initial alignment technology, the rapid fine alignment can be achieved.Besides, the paper finishes the system implementation of the reverse navigation algorithm. The paper builds the system circuit board based on TMS320 C6743DSP and CPLD,A/D sampling circuits and other peripheral circuits, and together with the inertial device(including the fiber optic gyros and accelerometers) forms a FOG Strapdown Inertial Navigation System. The paper analyzes the system and the working process of fiber optic gyros and accelerometers. In this paper,the author designs the sampling and processing circuits of signal (system circuit board),the sampling hardware circuits of accelerometers and temperature. Moreover, the design of FOG signal interface modules are introduced. The paper also introduces the BOOT design of system program and finishes the building and debugging finally.By the built FOG SINS, the paper carries out the initial alignment experiments on the tentative turntable. Making use of reverse navigation algorithm in the initial alignment technology, the paper reduces the time of SINS alignment.