双路闭环谐振式光纤陀螺数字信号检测系统的设计与实现

发布时间：2018-09-08 09:54

【摘要】：谐振式光纤陀螺(RFOG)与传统的干涉式光纤陀螺一样基于光学Sagnac效应,其突出优点是可用短光纤获得高精度,是光纤陀螺小型化的重要途径。相对于模拟信号检测系统,RFOG的数字信号检测系统具有体积小、处理速度快、稳定性好和抗干扰能力强等优点。相对于单路闭环检测,双路闭环RFOG系统能够提高系统的线性度和动态范围。论文以FPGA为核心,设计并实现了双路闭环RFOG的数字信号检测系统。具体来说,本文主要开展了如下研究工作： (1)基于正弦相位调制解调技术设计并实现了RFOG的数字信号检测系统。利用CORDIC算法,在FPGA上实现了正弦调制信号的产生及信号的同步解调。实验结果表明,研制的数字信号检测系统等效输入噪声为9.95nV√Hz。 (2)基于伺服控制器设计并实现了RFOG的谐振频率伺服回路。在比例积分控制器的基础上加入重积分项,用于抑制谐振频率线性漂移引入的锁定偏差,实验结果表明,研制的伺服控制器极大地减小了锁定回路的稳态误差。同时,通过设计自动控制复位技术,有效地减小了伺服控制器溢出复位脉冲的影响,复位重新锁定时间从8s降低到了5ms。 (3)基于相位调制器设计并实现了高精度的等效移频器。通过改进数字锯齿波调制技术,提高了移频器的移频精度和移频范围。设计的移频器频率分辨率可达0.0075Hz,对于谐振腔直径为12cm的RFOG,其等效检测精度为0.03°/h。 (4)基于串口通信设计并实现了计算机与FPGA之间的通信系统,实现了对FPGA参数的实时控制调节以及对FPGA内部信号的高速采样,增强了系统的灵活性和实用性。将上述以FPGA为核心的数字信号检测系统应用于双路闭环RFOG系统,实验结果表明：在1s积分时间下,谐振频率伺服回路等效锁定精度为0.18°/h(1σ)；在105s积分时间下,陀螺输出的零偏稳定性优于0.5°/h；相对于单路闭环检测,双路闭环检测RFOG系统将检测范围从±215°/s扩大到了±1507°/s,提高了7倍,在相同的±215°/s检测区间内,标度因素的非线性度从1.2%降低到了0.02%(200ppmm),改善了60倍。
[Abstract]:The resonator fiber optic gyroscope (Rfog) (RFOG) is based on the optical Sagnac effect just like the traditional interferometric fiber optic gyroscope. Its outstanding advantage is that it can obtain high precision by using short fiber optic fiber, which is an important way to miniaturize the fiber optic gyroscope. Compared with the analog signal detection system RFOG digital signal detection system has the advantages of small volume fast processing good stability and strong anti-jamming ability. Compared with single closed loop detection, double closed loop RFOG system can improve the linearity and dynamic range of the system. Taking FPGA as the core, this paper designs and implements a digital signal detection system of double closed loop RFOG. Specifically, the main research work of this paper is as follows: (1) the digital signal detection system based on RFOG is designed and implemented based on sinusoidal phase modulation and demodulation technology. Using CORDIC algorithm, sine modulation signal generation and synchronous demodulation are realized on FPGA. The experimental results show that the equivalent input noise of the digital signal detection system is 9.95nV Hz. (2) the resonant frequency servo loop of RFOG is designed and implemented based on servo controller. The double integral term is added to the proportional integral controller to suppress the locking deviation caused by the linear drift of the resonant frequency. The experimental results show that the developed servo controller greatly reduces the steady-state error of the locking loop. At the same time, by designing automatic control reset technology, the effect of overflow reset pulse of servo controller is reduced effectively. The reset and reset time is reduced from 8 s to 5 Ms. (3) based on the phase modulator, a high precision equivalent frequency shifter is designed and implemented. By improving the digital sawtooth wave modulation technology, the frequency shift accuracy and frequency range of the frequency shifter are improved. The frequency resolution of the designed frequency shifter can reach 0.0075 Hz. For the RFOG, whose resonator diameter is 12cm, the equivalent detection accuracy is 0.03 掳/ h. (4) the communication system between computer and FPGA is designed and implemented based on serial communication. The real-time control of FPGA parameters and the high-speed sampling of FPGA internal signals are realized, which enhances the flexibility and practicability of the system. The digital signal detection system with FPGA as the core is applied to the double-channel closed-loop RFOG system. The experimental results show that the equivalent locking accuracy of the resonant frequency servo loop is 0.18 掳/ h (1 蟽) at 1s integral time, and at 105s integral time, the equivalent locking accuracy of the resonant frequency servo loop is 0.18 掳/ h (1 蟽). The zero bias stability of gyroscope output is better than 0.5 掳/ h, and compared with single closed-loop detection, the double-channel closed-loop detection RFOG system expands the detection range from 卤215 掳/ s to 卤1507 掳/ s, which is seven times higher than that of the same 卤215 掳/ s detection range. The nonlinearity of scale factor is reduced from 1.2% to 0.02% (200ppmm), which is improved by 60 times.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.23

【共引文献】