Research On Initial Alignment Technology For Strap-down Compass System Based On FOG

Fiber Optic Gyroscope Strap-down Inertial Navigation System (FOG -SINS) is applied broadly in military and civil manufacture, owning to its unique advantages. In the future, the FOG-SINS will perform a leading trend in the INS development; this paper is based on lab's FOG Strap-down Compass navigation System which is developed by ourselves; With the purpose of practical project, the SINS's initial alignment method is particularly studied in this paper.Coarse alignment of the SINS is required to gain an initial coarse attitude matrix; in the paper, the inertial frame improved coarse alignment is introduced; with analytic coarse alignment and horizon leveling plus azimuth estimation coarse alignment, then expatiate on their advantages and disadvantages respectively. The corresponding simulation result is also given out.Fine alignment of the SINS aims at getting the more accurate attitude matrix. Based on this purpose, the state equation and the observation equation in inertial frame are derivate, and then make use of the Kalman filter to estimate the misalignment angles between the coarse matrix and the true matrix.Considered the flexibility and the rapidity for the modern weapon system, fine alignment which bases on Linear Quadratic (LQ) optimal control is discussed detailedly. First study the linear error model applied in SINS on the swaying base, for the step-wise disturbance which appears in the system, anti-jamming designs by using differential transformation method are done. Then using the discrete dynamic programming recursive algorithm, calculates the optimal control gain, get the amendatory angular velocities and accomplish the fine alignment procedure.