Research On Internal Damping Technique For Strap-down Attitude Measurement System With Ring Laser Gyroscope

It is very important for the warship to improve autonomous measurement accuracy of Strap-down Attitude Measurement System(SAMS)with Ring Laser Gyroscope.In the autonomous navigation state,there are periodic errors,such as Schuler,Foucault and Earth oscillation amplitude error in SAMS.And these errors can be restrained through the internal damping method.This thesis carries out research on internal damping technique for SAMS.The main research contents are as the following parts:1.A novel damping network with continuously adjustable damping ratio is designed in this thesis.The error model of SAMS is deduced and analyzed,a novel damping network with continuously adjustable damping ratio is designed according the principle of lead-lag correction of automatic control theory.And the damping ratio can be changed via adjusting the correction coefficient of the damping network.SAMS is a discrete system,so the damping network is discretized with bilinear transformation,and configured as a differential equation into the solution program.2.Internal horizontal damping technique of SAMS.FIR and IIR digital filter is designed to extract carrier acceleration,and the delay characteristics of these digital filters are analyzed.On the basis of analysis on the system error model,the relationship among the carrier acceleration,damping ratio and attitude angle error is deduced.Three kinds of adaptive control are designed to realize the adaptive damping scheme.And the damping switching criterion of the damping switching scheme is determined.Finally,the adaptive damping scheme and the damping switching scheme are validated via the data collected from the experiment on the sea.3.In order to suppress overshoot error of internal damping switching,the discrete self-compensation method is proposed.The reason of overshoot error is studied with the Laplace transform.Aiming at the initial value in Laplace transform,the overshoot error is suppressed by compensating the carrier's velocity at the time of damping switch.A simulation is designed to compare the discrete self-compensation method and variable damping method to suppress the overshoot error.4.Internal absolute damping technique of SAMS.The mechanism of azimuthal damping attenuate earth oscillation error is analyzed.The transfer function of carrier acceleration to azimuth is deduced.The internal absolute damping is verified via the data of the experiment on the sea,and the limitation of the internal absolute damping is analyzed.Finally,the scheme of switching between no damping and internal horizontal damping is determined.