Noise Analysis And Digital Closed-loop Control System Design For FOG

Fiber Optic Gyroscope (FOG) is a new angular rate sensor based on the Sagnac effect.Compared with the traditional mechanical gyroscope, FOG has the advantages of wide dynamic range, low cost, light weight, long life and high reliability.And this makes it widely applied in the navagation control system of aircrafts, spacecrafts and ships. This paper studies on the noise and the signal detection method and presents new theory methods at scheme establishment signal detection and processing. The research method has been tested by experiment and got good results. The following are the main work of the paper:Firstly, because all kinds of noise in the high precise IFOG have been the most important impact and are the restriction factor to IFOG.'s precision. In this paper every kinds of noise brought by optic component and environmental impact was analyzed, so a steady theoretical foundation for the reduction or elimination of the noise and the increase of signal detection have been establishedSecondly, Completed the implement of this system based on FPGA and two methods based on the second closed-loop were proposed to restrain the error brought by this instability of Y waveguide, which will induce a drift on the closed-loop gain. Then the dual close-loop scheme based on Four-states modulation which is more simple in demodulation and more quicker in error detection, was selected as the experimental scheme by comparative analysis.Lastly, according to the design requirement of weak signal detection system and the characters of interference signal, the FOG closed-loop control circuit was established by appropriate component and the software was designed with VHDL language, then the four-state dual close-loop control system based on four-state was realized in FPGA.Then, both the hardware and software the system were test in experimentation,and the resault was given lastly.