MEMS陀螺六阶连续带通多反馈∑△M闭环控制系统

设计了一种用于MEMS陀螺敏感模态的六阶连续带通多反馈∑△M闭环控制系统,以及相应的系统参数多目标优化方法．与以往的低通∑△M闭环控制系统相比,该系统不仅具有更好的噪声整形特征,能较大程度抑制陀螺噪声,而且易于在PCB电路上实现．由于整个闭环系统非常复杂且非线度较高,采用遗传算法对系统参数进行了多目标优化．系统优化之后的仿真结果显示,当输入角速度为200°／8时,在64Hz带宽范围内陀螺信号的信噪比可大于90dB,底噪为-120dBV／／Hz．最后采用常压封装的z轴全对称解耦结构的绝缘体上硅陀螺在PCB电路上进行了系统功能验证,测试结果显示系统具有明显的带通噪声整形特征,陀螺底噪为-100dBV／Hm．     

谐振式光纤陀螺的数字检测方案及其优化设计

提出了一种基于 DSP 芯片实现的双频率数字调制谐振式光纤陀螺系统的闭环检测方案。在此方案中,利用带通滤波器从探测器的输出光强信号中提取其基波频率的正弦信号,通过相关检测原理去掉干扰的噪声,并利用低通滤波器提取与探测器输出光强幅度直接成正比的直流信号,将其转换成相应的谐振频差,利用此频差即可求得陀螺的旋转角速度。此方案检测线路简单,操作方便,基于 DSP 芯片的实现则大大提高了系统处理速度。同时,还利用 Matlab 软件对检测系统中的滤波器参数进行了优化设计,提高了系统的检测精度。     

Dynamic instabilities in a single-axis gyroscope subjected to stochastic angular rate perturbations

Instabilities in a vibratory MEMS gyroscope that is subject to stochastic fluctuations in input angular rates are investigated. The vibratory-type gyroscope considered in the present study is of the spring-mass type. An asymptotic approach based on the method of stochastic averaging has been employed for this purpose, and closed-form conditions for mean square stability of dynamic response are obtained for the case of exponentially correlated noise. Results are shown to depend only on those values of the excitation spectral density near twice the natural frequencies and the combination frequencies of the system. The presented results remain valid if the stochastic parametric excitation has a small correlation time compared with the system relaxation time. Stability predictions have been illustrated via stability diagrams in the power-spectral-density–damping-ratio space.     

数字闭环光纤陀螺输出滤波器设计

在数字闭环光纤陀螺中,数字输出信号由高抽样率的反馈信号抽取得到,为避免抽取过程中发生频域混迭,应加入输出滤波器对信号进行低通滤波。根据多抽样率数字信号理论,采用多级抽取滤波器的设计方法,为陀螺设计输出滤波器。和一级低通滤波器比较说明,所设计的三级抽取滤波器,运算量小、滤波效果好。测试结果表明,加入输出滤波器不改变陀螺静态特性,抑制了振动时引起的高频误差,提高了陀螺精度。     

伪随机调制在全数字闭环光纤陀螺中的应用

伪随机调制信号的抗干扰能力强,获得同样的信号,对系统正常运行的干扰程度比其他测试信号低。光纤陀螺的输出信号微弱,背景噪声强,在频域随机分布,增加了信号处理的难度。结合伪随机调制的优势,在原有的数字闭环信号处理的基础上,提出了一种新的信号处理方案:伪随机调制解调方案,与数字闭环方案相互配合,有效提取环境因变量,反馈至系统使之实时做出补偿,提高陀螺稳定性。     

对称复位调制技术在小型化光纤陀螺中的应用

2π复位调制是光纤陀螺全数字闭环处理技术的一个重要环节。由于小型化Y波导的半波电压提高,小型化光纤陀螺的调制信号达不到2π复位的要求。通过分析闭环复位的原理,提出了一种新的对称复位调制技术,成功实现了小型化光纤陀螺的复位调制闭环控制。     

Higher Order Noise-Shaping Filters for High-Performance Micromachined Accelerometers

Micromachined inertial sensors that have been incorporated in sigma-delta force-feedback loops have been proven to improve linearity, dynamic range, and bandwidth, and also provide a direct digital output. Previous work mainly focused on using the sensing element only to form a second-order single-loop sigma-delta modulator (SigmaDeltaM); however, the advantages of higher order single-loop electromechanical SigmaDeltaM have not been fully explored. High-performance inertial sensors require higher signal-to-quantization noise ratio (SQNR). This paper presents topologies for higher order single-loop electromechanical SigmaDeltaM with optimal stable coefficients that lead to a better SQNR. The topologies have good immunity to fabrication tolerances, which was verified by Monte Carlo analysis. The topologies are applicable not only to accelerometers but also to other inertial sensors such as gyroscopes.     

Modal Coupling in Micromechanical Vibratory Rate Gyroscopes

The authors present modeling approaches to describe the coupling of modes in a resonant vibratory rate gyroscope. Modal coupling due to off-diagonal stiffness and damping terms is considered. Three analytical modeling approaches are presented in the context of a$z$-axis micromechanical vibratory rate gyroscope fabricated in an integrated polysilicon surface-micromachining process. The first approach is based on frequency-response analysis of the gyroscope output. The second approach takes the route of state-space-based system identification to identify the modal-coupling parameters. A third approach based on measured vibration data identifies the coupling parameters due to stiffness and damping. These three methods are then applied to predict the extent of displacement and force coupling between the drive and the sense axes of an existing device as a function of varying degrees of matching between the resonant frequencies associated with the drive and the sense modes. Experimental data show that as the resonant frequencies of the drive and sense modes are brought closer together, an improvement in overall resolution and scale factor of the device is obtained at the expense of an enhanced coupling of forces to displacements between the two axes and the onset of instability for an open-loop sensing implementation.     

石英陀螺闭环自激驱动电路(英文)

为使石英陀螺满足高性能、小型化和集成化需求,设计石英陀螺专用集成电路接口芯片势在必行.本文通过分析石英陀螺表头的机电特性,得出方波驱动方式是系统性能和复杂程度的折衷.据此设计了一种闭环自激驱动电路.该电路与石英结构形成反馈环路,从而实现陀螺的自激驱动,并通过自动增益控制电路实现幅值稳定.该电路已用0.5μm CMOS工艺实现,测试结果表明该电路可以实现稳幅稳频的驱动,幅值稳定度0.01%.集成该驱动电路的石英陀螺系统达到战术级性能.     

剑杆织机前馈-反馈张力控制系统的分析与设计

在分析剑杆织机张力控制中噪声源及噪声特性的基础上,提出控制结构和控制器的设计方法,选择合适的模拟低通滤波器,对检测通道的高频振动信号和随机噪声进行滤波.针对周期性低频振动噪声,一方面,采用频谱分析定周期+相干平均法定信号的方法估计模拟低通滤波器后的周期性振动噪声,并在反馈通道进行补偿,提高控制性能;另一方面,采用频谱分...     

具有栅结构与静电梳齿驱动的电容式微机械陀螺的仿真、设计与测试

电容式陀螺仪是一种振动式陀螺仪,由于加工的特殊性使其具有了传统的陀螺无法比拟的优点,从而拓宽了其应用领域.为了提高陀螺仪的检测精度,本文提出了一种静电梳齿驱动、栅结构的电容式检测的微机械陀螺仪的设计方法,并分析了其工作原理.运用ANSYS软件对陀螺结构进行了仿真和模态分析,仿真结果与理论计算结果相接近.所设计的陀螺结构采用体硅标准工艺方法进行了设计,并对其进行了流片加工和封装,最终得到了电容式微机械陀螺仪.实验测试的结果表明,陀螺驱动模态的固有频率为4.06kHz,灵敏度为0.027 9 v/((°)s-1).     

基于锁相技术的微机械陀螺闭环驱动电路

传统的闭环驱动电路其输出信号的频率与微机械陀螺驱动方向的固有频率存在一定偏差,且频率抖动较大,系统的建立时间较长．基于上述不足,在分析微机械陀螺闭环驱动方式工作原理的基础上,提出一种基于锁相技术的闭环驱动电路方案,电路进入稳定工作状态时,交流驱动电压与驱动方向敏感电流的相位及频率一致．微机械陀螺在驱动方向谐振,显著改善了输出信号的频率特性．仿真结果表明,这种闭环驱动电路输出信号频率与微机械陀螺驱动模态固有频率完全一致,频率抖动及系统建立时间分别是传统闭环驱动电路的38％和50％．通过实验验证了该方法的可行性     

Discrimination of wide-field images as a test of a peripheral-vision model

In order to test a model of peripheral vision, various contrast sensitivity functions (CSF's) and fundamental eccentricity constants (FEC's) [see J. Opt. Soc. Am. A 8, 1762 (1991)] were applied to real-world, wide-field (6.4 degrees-32 degrees eccentricity) images. The FEC is used to model the change in contrast sensitivity as a function of retinal eccentricity. The processed test images were tested perceptually by determining the threshold FEC for which the observers could discriminate the test images from the original image. It was expected that higher CSF sensitivity would be associated with higher FEC's; and in fact, for images processed with low-pass (variable-window stimuli) CSF's, the threshold FEC's were larger for the higher-sensitivity (pattern-detection) CSF than for the lower-sensitivity (orientation detection) CSF. When two higher-sensitivity CSF's were compared, the bandpass (constant-window stimuli) CSF resulted in essentially the same FEC threshold as did the low-pass (variable-window stimuli) CSF. The fact that the FEC compensated for complex differences in the form of the CSF suggested that the discrimination task was mediated by a limited range of spatial frequencies over which the two CSF's were similar. Image contrast was then varied in order to extend the range of spatial frequencies tested. The FEC's estimated with the lower-contrast test images were unchanged for test images obtained with the high-sensitivity, bandpass CSF but increased for test images obtained with the high-sensitivity, low-pass CSF. These results suggest that peripheral contrast sensitivity as used in the present discrimination task is based on a high-sensitivity, bandpass CSF. The peripheral-vision model validated by the present analysis has practical applications in the evaluation of wide-field simulator images as well as area-of-interest or other foveating systems.     

变结构PID在微机械陀螺仪闭环驱动电路中的应用

为满足微机械陀螺仪(MMG)闭环驱动电路起振快速、无超调且稳态精度高等要求,提出了一种基于FPGA的数字化变结构PID控制器,并以其为核心构建了微机械陀螺仪的数字化闭环驱动电路.通过构造以控制误差为自变量的比例增益、积分增益和微分增益函数,使变结构PID的结构和参数能够根据瞬时误差的变化而变化,以提高闭环驱动电路的性能.针对某型微机械陀螺仪敏感结构参数,进行了SIMULINK仿真,仿真结果表明以变结构PID为核心的闭环驱动电路是可行的.起振实验结果表明,经典PID构成的闭环驱动电路,其检测电压的幅值超调量达到了75%,稳定时间为2 s;采用变结构PID控制器后闭环驱动检测电压的幅值无超调且稳定时间为0.7 s;1 h的稳定性实验表明,采用经典PID时检测电压幅值的长期稳定性为2.73×10-5V,采用变结构PID时其稳定性为2.68×10-5V,证明变结构PID可以兼顾系统在快速性、超调量和稳态精度等方面的要求.     

Pole assignment using state feedback with time delay in friction-induced vibration problems

The dynamic behavior of friction-induced vibration problems is governed by second-order differential equations having asymmetric matrices, due to the coupling of structures and external loads, which are functions of some parameters. Asymmetric systems are prone to unstable vibration (flutter) as a parameter reaches a critical value. Placement of these unstable poles to the left-hand half of the complex pole plane for stabilization can be achieved by active (feedback control) and passive means (structural modification). Moreover, placement of poles is also done to achieve the desirable dynamic response and system performance. However, such active pole assignment control introduces inherent time delays in the feedback control loop. This paper presents a method for assigning complex poles to second-order damped asymmetric systems by using state-feedback control while considering a constant time-delay in the feedback control loop. The control strategy is based on receptances of the symmetric part of the asymmetric open-loop system (without time delay), which can be easily obtained from transfer function measurements. This method does not require the knowledge of mass, damping and stiffness matrices, and hence circumvents the modeling errors (finite element or reduced order). In this research, with numerical examples, it is shown that by means of active state feedback control and by using a relatively small number of available receptances, open-loop poles of the asymmetric system can be assigned precisely. The stability of the closed-loop system is analyzed by computing primary closed-loop poles and the associated critical time delay.     

Quantitative criteria for the design of dither-based quantizingsystems

This paper addresses the problem of designing quantizing systems employing dither. These are composed of a dither generator, a quantizer, a subtracting block and a low-pass digital filter. Quantitative criteria for choosing the parameters that influence the resolution and accuracy of the quantizing system are given, and the system performance is determined under worst, best, and average conditions for discrete binary, uniform, and Gaussian dither signals. The results presented also can be applied when the signal plus input-referred noise are quantized     

非线性系统随机振动响应限界极大极小控制

研究非线性系统随机振动的限界极大极小最优控制。引入调控变量放大振动峰响应,用高阶多项式作为性能指标函数,提高其中峰值占比,建立非线性随机振动峰响应的极小化最优控制问题方程;应用随机动态规划原理建立HJB方程,考虑控制作用的有界性,确定半连续与跳变型极大极小最优控制律;最后通过数值结果,说明该最优控制能够有效地抑制非线性随机振动,并调控变量、控制界限、跳变型控制等对于控制效果的影响。     

环形子孔径拼接算法的精度影响因素分析

优化的拼接算法是环形子孔径扫描测量大口径非球面光学元件的关键问题。针对一种基于离散相位值的环形子孔径拼接算法,从精度评定判据入手,对随机噪声、高阶噪声、重叠区宽度及子孔径数目这几个主要影响因素进行了数值仿真分析。结果表明,该算法对高阶噪声和随机噪声均不灵敏,高阶噪声的影响略大于随机噪声的影响;对口径和相对口径较大的非球面,相邻子孔径间重叠系数应大于 0.15,对于非球面度不大的非球面,重叠系数可大于 0.25, 能以较高精度求得拼接参量。     

Theoretical principles for establishing a hierarchy of dynamicaccuracy with the integral-square-error as an example

This paper presents the possibility of applying maximum dynamic errors to establish a hierarchy of measuring systems intended for dynamic measurements. To determine maximum errors, it is necessary to apply strictly defined calibrating signals. The shape analysis and necessary and sufficient conditions for such signals to exist are presented with the integral-square-error criterion as an example. Moreover, limitations imposed on calibrating signals depending on the low-pass, high-pass, or bandpass types of calibrated systems are also discussed. The values of the maximum errors determined by means of the signals mentioned above make it possible to create accuracy classes and the resulting hierarchy of dynamic accuracy, valid regardless of the measured signal shape. The solutions presented in the paper refer to both measuring analog systems and systems with analog-to-digital (A/D) conversion     

基于听觉感知的不同航速稳态舰船噪声合成

声纳人员培训和人耳辨识舰船声实验中常需要完备的敌我舰船辐射噪声样本,但实录各国舰船噪声几乎是不可能的。因此,合成与真实水下声样本听觉感知相同的舰船辐射噪声十分必要。研究了舰船航速对其辐射噪声的影响及人耳听音的临界带通特性,通过已知的零散舰船噪声样本合成目标舰船在其它未知状态下的辐射噪声。采用临界带通滤波和线谱迭加方法,分别合成了目标舰船在低、中、高三种不同航速下的稳态辐射噪声。为了验证合成声的有效性,进行了主观评价实验,采用成对比较法验证了15组不同航速状态下的合成舰船噪声样本。结果表明,合成舰船噪声样本能够被人耳有效识别,准确率达93%。