Space radiation effect on fibre optical gyroscope control circuit and compensation algorithm

The process of a γ-irradiation experiment of fibre optical gyroscope （FOG） control circuit was described, in which it is demonstrated that the FOG control circuit, except for D/A converter, could endure the dose of 10krad with the protection of cabin material. The distortion and drift in D/A converter due to radiation, which affect the performance of FOG seriously, was indicated based on the elemental analysis. Finally, a compensation network based on adaptive neuro-fuzzy inference system is proposed and its function is verified by simulation.     

光纤陀螺捷联航姿系统CAN总线设计

针对光纤陀螺捷联惯性航姿系统对通讯实时性、可靠性和抗干扰要求高的特点,基于独立的CAN控制器SJA1000设计了光纤航姿系统CAN总线通讯节点,提出了CAN总线软硬件设计方案,解决了CAN控制器与系统主处理器地址和数据线分离之间所存在的问题.与传统的RS232/422/485、1553B等相比,采用CAN总线有助于将航姿系统、控制设备、测试设备、各种传感器及载体其它电子设备,通过CAN总线互连,构成一个高速、可靠、廉价的现场总线控制系统.考到虑航姿系统的特殊应用背景,制定了CAN应用层协议.实验及实际应用表明,该航姿系统通讯实时性、可靠性好,抗干扰能力强.     

光纤陀螺仪在惯性测量组合中的应用分析

介绍了闭环方案的干涉型光纤陀螺仪和捷联惯性测量组合。针对惯测组合的特定应用，分析了其面向的系统环境。通过对环境引入陀螺仪的误差项及其控制方案进行了具体分析和比对，提出了较优的应用方案和测试参数。采用该方案的惯性测量组合进行了充分实验和实际应用，证明了其可行性。     

基于对称性评估的保偏光纤偏振轴检测技术

提出一种基于端面图像对称性特征的偏振轴检测算法。该算法利用图像极坐标变换来实现图像的对称性检测,使用金字塔搜索法快速寻找最优对称轴,确定偏振轴向。所提算法利用图像的全局性特征而不依赖于应力区边缘点位置实现精确定位,对图像清晰度要求显著降低。实验结果表明,所提算法具有较高的准确性和精确性(±0.1°),其稳健性大幅增强,且算法速度提升了近1.5倍。     

消除光纤陀螺死区的方法研究

光纤陀螺的工作原理和检测方法使得它从理论上将不存在死区，光纤陀螺的死区是因为电路的交叉耦合以及输出方式造成的。文中阐述了光纤陀螺死区的测量方法，分析和推导了死区产生的机理，提出了通过引入正弦信号减小或消除死区的具体措施，并进行了试验验证。结果表明，该措施可以大大减小或消除光纤陀螺死区，同时对陀螺的静态精度不产生影响。     

用A/D和FPGA实现的加速度计数据读出系统

加速度计是惯性导航系统的核心部件，通常加速度计输出为模拟电流信号，为便于导航计算机的数字处理，需经过A／D、I／F或V／F转换。针对应用背景实时、高精度、宽动态范围的要求，文中采用高分辨率模数转换器和嵌入式现场可编程门阵列组成石英挠性加速度计串行数据读出系统，设计了系统的硬件和软件。系统解决的几项关键技术，如数据采集逻辑电路设计、高分辨率A／D的接口电路设计等，可为其它要求宽动态范围的传感器接口系统所利用。     

Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro

The phase modulation and the closed-loop controller can generate electrical crosstalk-coupling in digital closed-loop fibre optic gyro. Four electrical cross-coupling paths are verified by the open-loop testing approach. It is found the variation of ramp amplitude will lead to the alternation of gyro bias. The amplitude and the phase parameters of the electrical crosstalk signal are measured by lock-in amplifier, and the variation of gyro bias is confirmed to be caused by the alternation of phase according to the amplitude of the ramp. A digital closed-loop fibre optic gyro electrical crosstalk-coupling model is built by approximating the electrical cross-coupling paths as a proportion and integration segment. The results of simulation and experiment show that the modulation signal electrical crosstalk-coupling can cause the dead zone of the gyro when a small angular velocity is inputted, and it could also lead to a periodic vibration of the bias error of the gyro when a large angular velocity is inputted.     

Effect of radiation-induced color centers absorption in optical fibers on fiber optic gyroscope for space application

The effects of color centers' absorption on fibers and interferometric fiber optical gyroscopes(IFOGs) are studied in the paper. The irradiation induced attenuation(RIA) spectra of three types of polarization-maintaining fibers(PMFs), i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers' absorption on RIA and mean wavelength shifts(MWS) at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient(RWC) degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.     

保偏光纤偏振特性自动测试系统的研制与开发

介绍了保偏光纤偏振特性的基本测试原理,给出了高精度检偏系统的光路结构,硬件检测电路和分析软件的结构框图,并对实验结果进行了精度分析。实验表明:光功率测试范围可达0 2nW—2mW,测得2m长保偏光纤最大消光比47 2dB,对于40dB以下的偏振态测量,误差优于±0 1dB。