Resonator Fiber Optic Gyro Digital System Design

Gyro is a kind of important inertial sensor, and it is a basic part of navigation or guidance. The resonator fiber optic gyro (R-FOG) which is based on Sagnac effect has some special advantages which other gyros cannot replace. R-FOG is built up by solid parts, so it can endure bigger vibration and acceleration, and it has a longer working time compared with traditional mechanical gyro. At the same time, it has broad dynamic arrange, low power consumption, and small weight. R-FOG uses a fiber resonator ring as a central sensor part, which transfers Sagnac effect to the shift of resonant frequency. Compared with interferometric fiber optic gyro (I-FOG) which senses the phase signal, R-FOG theoretically has higher accuracy and better dynamic arrange. Because Sagnac effect is very weak, the detection of signal is in a very significant position of the gyro system. This paper made use of digital signal processing technology to design a detecting system based on DSP and FPGA. After building a model for the operation of detection and feedback control, optimizing design was carried out based on simulation. And then, cooperative debug was done as well as the lock of the whole loop.At first, this paper introduced the whole construction of R-FOG, and then analyzed its working principle based on Sagnac effect and the property of resonator. Considering the demanded accuracy for detection, it figured out the function and target of the digital system. Because the word length if not enough for the demand of system, it is suggested to overcome the A/D's quantization error by repeated sample and average technology. In order to improve the precision of feedback control signal outputted by D/A, different digital steps were combined before output. For analyzing and proving these methods, some calculating experiments were finished with Matlab. Based on that the demodulation output signal is linearly versus the shift frequency near the resonant frequency, a mathematic model of object controlled was set up. Through theoretic analysis and simulation, the algorithm and the optimized parameters for loop control were chosen.After the scheme of the whole system was decided, an electronic system was designed based on DSP and FPGA. Through the cooperative work of both of them, the system finished the synchronous detection and demodulation, and it also realized the extension of accuracy in hardware. At the same time, the algorithm of loop control was realized in digital system where DSP is the core. Finally, through debugging the digital system connected with optic route, the method of modulation and detection were proved. By observation of the result of frequency lock, we proved the means we taken to track and lock the frequency in a loop, which built a foundation for the research of the whole R-FOG...