Research Of Data Collecting Technique And Initial Alignment In Strapdown Inertial Navigation System

Strapdown INS is a type of Inertial Navigation Systems. Compared with Platform INS, Strapdown INS has the advantages of low volume, low weight, low cost and high reliability. Strapdown INS leads the trend of INS. The thesis stems from part of a certain national key fundamental security project, and, based on SIMU-123, deals with two key techniques of Strapdown INS in order to pave the way for further research.Main work done is as follows:1. Design of data-collecting electronic circuit of the Strapdown INS as well as relevant software development. Data-collecting electronic circuit is the communication interface between inertial instruments and navigation computer. At the same time, as a connection with the outside, the circuit has to be anti-interference, in other words, the circuit is not only the data communication inteface, but also the protective insulation interface of navigation computer. In aspects of system principle, choice of devices, design of hardware and development & debugging of software, the thesis sheds light on the developing process of 12-channeled, high-speed data-collecting system. The use of the data-collecting system shows that the basis and design of the system is feasible and meets the demands of Strapdown INS. In accordance with modularization of software engineering theory, C language is adopted on the DOS platform to develop the program, so as to lay a foundation for embedment in the future.2. Research on initial alignment method of Strapdown INS. Initial alignment is a key technique of INS, which plays an important role in the performance of navigation system. The thesis discusses the self-alignment, in other words, the method of utilizing the acceleration rate of the system itself, gravity force measured by gyro, and rotation information of the earth to achieve independent alignment. First, the thesis introduced the analytical sketchy alignment and one rank sketchy alignment, which can roughly determine the initial value of the Strapdown matrix as the initial value for precise alignment. Having studied the inertial alignment methods based on the classical controltheories, the thesis realizes horizontal alignment and azimuth alignment by using output feedback control, establishes the system error equation, and proposes the determination method of system parameters. Based on it, Kalman filter and Hx filter are applied to the initial alignment of Strapdown INS and, in addition, an analysis of simulation is made.