谐振式光纤陀螺数字系统设计

【作者】 沈庆；

【导师】 金仲和； 马慧莲；

【作者基本信息】 浙江大学 ， 微电子学与固体电子学， 2006， 硕士

【摘要】 陀螺是重要的惯性传感器,是导航和制导系统的基础部件。基于Sagnac效应的光学陀螺有许多其他陀螺无法取代的独特优点,它全部由固态器件组成,相对于传统的机械陀螺来说,可以承受更大的振动和冲击,具有寿命长、动态范围宽、功耗低、质量轻等优点。谐振式光纤陀螺(R-FOG)用一个光纤环形谐振腔作为核心敏感部件,把Sagnac效应反映到谐振频率的变化上,相对于基于相位敏感的干涉式光纤陀螺,理论上具有更高的精度和更大的动态范围。由于Sagnac效应是一种极其微弱的效应,因此信号检测在陀螺系统中占有非常重要的地位。论文利用数字信号处理技术,设计了一个基于DSP和FPGA的检测系统,并对检测和反馈控制算法进行了建模仿真和优化设计。在此基础上,完成了整个R-FOG数字系统的联合调试,并顺利完成整个系统的锁定。 论文首先介绍了整个谐振式光纤陀螺数字系统的结构设计,然后按照Sagnac效应与环形腔的谐振特性,分析了整个陀螺系统的工作原理,结合目前系统检测精度要求,提出了数字系统需要实现的功能和参数指标。考虑到目前A/D转换器、D/A转换器的量化位数与系统的要求有一定差距,在A/D端,提出利用多次采样平均技术和数字滤波技术来抑制由于位数不足带来的量化噪声,在D/A反馈控制端采用了不同台阶高度的组合技术提高控制的精度,并利用Matlab对相应的精度扩展措施进行分析验证。利用解调信号和谐振频率偏差在靠近谐振点附近的近似线性关系,对反馈控制对象建立了数学模型,经过理论分析和仿真计算,确定了环路的控制算法和最佳锁定参数。 在确定了数字系统方案的基础上,设计了一个基于DSP和FPGA的电子系统,通过两者的协同工作,实现了对光电信号的同步检测和解调,并把精度扩展的方法在硬件上实现。同时,以DSP为核心在数字系统上实现了环路控制算法。最终,通过数字系统与光路的联调,验证了数字调制方案的效果,也验证了整个检测方案的可行性。通过闭环的频率锁定实验,证明了环路的频率锁定方案的效果,为整个谐振式光纤陀螺系统的研制打下了基础。更多还原

【Abstract】 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更多还原