一种高性能电磁式微机械振动环陀螺

模态匹配和高的品质因数是提高振动环陀螺性能的关键。设计制作了一种电磁式微机械振动环陀螺,采用了全对称的结构以实现模态匹配。通过理论推导建立了陀螺灵敏度和机械噪声的数学模型,分析了陀螺参数对灵敏度及分辨力的影响。采用（100）晶向的单晶硅及MEMS体硅标准工艺加工了陀螺样片,该工艺简单,无需键合。器件频响实验结果表明,所设计的振动环陀螺驱动模态和检测模态频差小于0.5Hz,大气压下品质因数约为500,在1Pa的低真空下达到14000。锁相放大器测试结果表明,在-200 ~200 o/s测量范围内,陀螺分辨力为0.05o/s,灵敏度为0.2uv/ o/s。测试结果表明该陀螺能够实现模态匹配和较高的品质因数,具有较高的性能指标。     

抗过载环形 MEMS 固体波动陀螺设计加工与测试

本文针对传统MEMS振动陀螺在经历高过载过程无法存活且冲击前后参数变化大的问题,开展了抗高过载MEMS固体波动环形微机械陀螺设计、加工和测试方面的研究工作。首先,提出了全对称梁的陀螺结构形式,该结构能够有效的减小冲击过程在结构中造成的应力残留,配合止挡机构以及灌封技术能够提升陀螺在冲击过程中的存活能力,并在此基础上推导了陀螺的动力学方程和敏感轴冲击振荡运动函数,指出了敏感轴冲击模态的固有频率越高、品质因数越小则越有利于提高陀螺在敏感轴上的抗冲击特性。其次,利用有限元分析软件对陀螺结构进行了模态分析和冲击特性仿真,结果显示在15 000 g@10 ms的冲击作用下,陀螺的最大位移和应力分别为9.46μm和99.6 MPa,保证了陀螺结构具有较好的抗冲击裕度。再次,利用较为成熟的玻璃-硅键合和深硅刻蚀工艺实现了陀螺结构的加工,结合陶瓷封装实现了陀螺结构的真空封装,并基于驱动闭环和检测开环回路搭建了陀螺的测试系统。最后,在实验室环境下利用冲击台实现了对陀螺样机的冲击测试,冲击过程(脉宽0.6 ms)出现了多个5 000 g以上的峰值,最大峰值为16 050 g,陀螺响应时间约为1 s,冲击前...     

微纳卫星陀螺阵列系统信息融合

为了实现微纳卫星MEMS陀螺动态在线滤波,对MEMS陀螺阵列建模,设计可应用于动态过程的最优在线数据融合算法,建立陀螺阵列测试系统,并对融合滤波的陀螺系统的性能对比分析。首先,建立多个陀螺的量测模型。接着基于信息融合模型,使用Kalman滤波算法,对预测的协方差矩阵进无求逆运算迭代;然后,基于误差估计,对动态时变信号滤波模型建模,并给出了融合滤波方法;最后,搭建6个MEMS陀螺在线滤波系统,验证该算法的有效性。实验结果表明：滤波误差可降低为单陀螺采样误差的1/15,精度提高一个数量级;运算量相比层序式滤波减少为1/4,计算时间减少为1/3。本文所提算法在提高精度的基础上,显著提高了MEMS陀螺系统的性能指标,拓展了MEMS陀螺在微纳卫星的应用范围。     

基于改进SPI的多量程MEMS虚拟陀螺研究北大核心CSCD

文中设计了多量程MEMS虚拟陀螺,解决了现阶段微机电系统(MEMS)虚拟陀螺不能兼容载体对陀螺仪精度和量程的问题。提出一种改进SPI的新型数据采集方式,在改善数据读取速率的同时增强了数据实时性。在静态测试中,该阵列经过滤波融合后,1σ标准差降低了76.8%,零偏不稳定性降低了89.1%;在模拟动态测试中,通过选取最佳量程数据进行滤波融合与姿态解算,该阵列最终姿态角偏离程度最小。实验结果表明多量程MEMS虚拟陀螺融合效果与降噪能力都优于单一量程虚拟陀螺。     

微机械振动环陀螺

为了减小振动环驱动模态和检测模态的频率差从而提高陀螺性能,提出了一种采用电磁驱动、电磁检测的全对称振动环陀螺结构。采用MEMS体硅工艺完成该微机械振动环陀螺的加工,其结构在保持镜像对称的同时,还保持了中心对称,因此整个结构高度对称,有利于减小模态频率差。为有效跟踪陀螺驱动模态的谐振频率并稳定驱动模态的幅值,设计了闭环驱动控制电路。该电路由低噪声前置放大器、相位调整环节以及自动增益放大器(VGA)组成。测试结果表明,该陀螺两个模态频率差为0.27 Hz,实现了频率较好的匹配。在±200 °/s,测得陀螺灵敏度为8.9 mV/(°/s),分辨力为0.05 °/s,非线性度为0.23%。     

MEMS陀螺零偏温度补偿方法

MEMS陀螺零偏是惯性导航系统的主要误差源之一,而外界环境温度变化对MEMS陀螺零偏具有重要影响。针对上述情况,提出基于小波阈值去噪与RBF神经网络相结合的零偏温度补偿方法。通过设计好的实验方案采集与温度相关的MEMS陀螺输出数据,并采用不同的温度补偿方法进行零偏温度补偿。实验结果表明,与原始输出、多项式拟合及RBF神经网络相比,基于去噪RBF神经网络的零偏温度补偿方法精度更高,适应性更强,有效地提高了MEMS陀螺输出精度,进而提高惯性导航系统精度。     

光纤环温度性能分析软件设计

介绍了影响光纤陀螺温度性能的主要因素—Shupe效应,论述了基于LabVIEW软件设计开发的光纤环温度性能分析软件的程序组成和功能,并利用光纤环温度性能分析软件开展了内外热源两种工作条件下,光纤陀螺温度性能的仿真分析及与光纤陀螺测试结果的对比评价。结果表明,仿真分析结果与光纤陀螺测试结果一致,光纤环温度性能仿真分析软件能够将光纤环有限元分析结果与光纤陀螺输出有机结合。     

微型光纤磁传感器的设计与制作

提出了一种基于微机电系统(MEMS)扭镜结构的光纤磁场传感器,并利用对角度变化非常敏感的双光纤准直器对扭镜的扭转角度进行了检测.该MEMS光纤磁传感器由MEMS扭镜结构、磁性敏感薄膜和双光纤准直器组成.文中分析了器件的磁敏感原理和光纤检测原理,介绍了器件综合设计方法,并给出了器件的结构参数.利用MEMS加工技术成功制作出了MEMS光纤磁传感器样品,最终得到的磁传感器的尺寸为3.7 mm×2.7 mm×0.5mm.对磁传感器进行了实验测试,得到的输出实验值与理论值吻合.测试结果表明,该磁传感器的光纤检测灵敏度可达到0.65 dB/mT,最小可分辨磁场可达167 nT.将MEMS敏感结构与光纤检测相结合,该传感器兼备了两者的优点,结构紧凑、制作工艺简单、工作时无需电流激励.     

应用分层自适应匹配追踪重构MEMS陀螺信号

对含噪微机械系统(MEMS)陀螺信号进行小波分解重构时,真实信号对应的小波系数很难选取,故本文提出一种分层自适应匹配追踪算法(LAMP)来解决上述问题。建立了含噪MEMS陀螺信号中信号小波系数稀疏提取架构,将信号小波系数提取问题转化为含噪信号中信号小波系数稀疏性的恢复问题。比较已有稀疏重构算法,采用一种新的LAMP算法,在各种可能的小波系数组合中挑选出分解系数最为稀疏的一组,以此消除信号中的噪声小波系数,进而重构MEMS陀螺信号。实验表明:提出的LAMP算法的稀疏重构效果优于其他迭代贪婪重构算法;基于LAMP的信号稀疏小波重构方法,可以有效去除MEMS陀螺信号的大量噪声;去噪前后,纯MEMS陀螺数据解算的方位角平均累积误差由10.060 2(°)/h减小到5.034 6(°)/h,优于传统小波阈值重构法平均累积误差8.596 8(°)/h,显示了较好的应用效果。     

基于最小分辨率的MEMS陀螺漂移抑制方法研究

针对油气井MEMS陀螺定向测斜仪存在的漂移大,精度较低的问题,本文从实际工程应用角度出发,在研究MEMS陀螺仪输出信号漂移特性的基础上,提出了基于最小分辨率的MEMS陀螺漂移抑制方法,利用输出采样的差分值,从MEMS陀螺输出中将传感信号和漂移信号分离,同时通过静态测点对漂移进行估计.实验表明,该方法大幅提高了仪器测量精度,使定向精度提高50％以上,同时该方法为其它类似传感器漂移抑制提供了一种有益的参考.     

基于MEMS镍平面微弹簧尺寸误差分析

对微机电系统(Micro-Electro-Mechanical System,MEMS)加工的S型微弹簧垂直方向弹性系数影响最大的参数是弹簧线宽b。鉴于此,特针对采用LIGA工艺加工出的两组不同弹簧的线宽进行了精密测量,分析计算出加工误差对弹性系数的影响大小,并对S型微弹簧的设计提出几点建议。     

折叠梁刚度的误差灵敏度分析

对MEMS中并联或串联组合而成的两种折叠梁形式的总刚度进行了分析,分析了两种梁在总刚度相同的条件下对加工误差的灵敏度,指出在加工误差不可避免的情况下,选择合适的折叠梁结构来满足具体的运用要求。得出:除发生误差的情况之外,折叠梁对误差的灵敏度比单梁小得多。运用CoventorWave软件对梁结构在随机相对误差下进行了有限元仿真分析,验证了理论分析的正确性。     

无线加速度传感器的MEMS芯片ADXL202应用设计与集成

阐述了一种基于MEMS技术的芯片ADXL202的应用设计与集成。介绍了ADXL202的测试原理和主要参数设计原则，然后利用其集成了一种无线加速度传感器并进行了测试。实验结果表明：ADXL202非常适合于频率变化较为缓慢、加速度不太大的土木工程结构的测量；利用ADXL202所构成的无线加速度传感器，易安装拆除，适合在土木工程结构监测中应用。     

再论单键键槽对称度误差的检测与计算

对GB195 8 80《形状与位置公差检验规定》中推荐的单键键槽对称度误差检测的翻转打表法提出质疑 ,认为单键键槽对称度误差应是其截面误差和键长误差的综合结果 ;运用解析几何方法推导出单键键槽对称度误差与截面误差和键长误差的关系式 ,并分析了这两种误差对测量结果的影响系数 ,指出影响单键键槽对称度误差的主要因素是键长方向的对称度误差。     

微机械应力测试结构的温度特性和应力抑制方法

研究了典型微机械应力测试结构的温度特性及从源头上抑制热应力的方法。设计了一种可以代表微机械系统(MEMS)器件温度特性的应力测试结构,并分析了温度对其固有频率的影响机理。指出了与材料弹性模量、结构尺寸变化相比,轴向应力是影响该结构固有频率温度稳定性的主要因素,同时设计了一种可以释放热应力以及加工残余应力的应力隔离结构。考虑硅的线膨胀系数随温度变化的特性,通过建模仿真和实验测试获得了应力测试结构、应力隔离结构的轴向应力以及固有频率的温度特性。结果表明:在-50℃~+85℃,应力隔离结构将轴向热应力抑制到了应力测试结构的2个数量级以下,固有频率-温度系数由5.0×10~(-3)ppm/℃左右降到了5.0×10~(-5)ppm/℃以下。结果显示:设计的应力隔离结构具有非常良好的应力隔离效果,从源头上抑制了主要的温度影响因素引入整个微机械系统,可以应用于其它MEMS结构以获得良好的温度稳定性。     

微电子机械系统的力学特性与尺度效应

针对微电子机械系统（MEMS）材料的力学特性,工艺过程对力学特性的影响以及微执行器、微机器人的尺度效应等力学问题进行了研究。从力学角度提出了硅和常用的薄膜材料作为MEMS结构材料时应遵循的设计和加工原则,并系统地分析、归纳了静电、电磁、压电、形状记忆合金等各种微执行器的尺度效应特征。通过对机器蚂蚁、微型飞机、微型机器鱼等微机器人在微尺度下的动力学特性分析,得到微机器人在尺寸越小时越容易被驱动的结论,为设计和制作微机器人等复杂微系统提供了理论依据。     

Development of a novel boring tool with anisotropic dynamic stiffness to avoid chatter vibration in cutting: Part 1: Design of anisotropic structure to attain infinite dynamic stiffness

This paper presents a novel design method of the anisotropic structure to attain infinite dynamic stiffness to avoid chatter vibration in boring operations. Because a long and slender tool is used for boring operations, the stiffness of the tool holder is likely to decrease, resulting in low chatter stability. Although it is difficult to improve the stiffness of the boring holder itself, the nominal dynamic stiffness for the cutting process can be improved by designing an appropriate anisotropy in the dynamic stiffness of the boring tool. In this study, we formulate a theoretical relationship between the mechanical structural dynamics and chatter stability in boring operation and present the basic concept of tool design with anisotropic structure. In the actual tool design, ideal anisotropy may not be realized because of the influence of design error. Therefore, an analytical study was conducted to clarify the influence of the design error on the vibration suppression effect. Analytical investigations verified that the similarity of the frequency response functions in the modal coordinate system and the design of the compliance ratio according to the machining conditions are important. Furthermore, we designed a boring tool with an anisotropic structure which can achieve the proposed anisotropic dynamics. The frequency response function was evaluated utilizing FEM analysis. The estimated anisotropic dynamics of the proposed structure could significantly improve the nominal dynamics for boring operations.     

Assessment of dynamical properties in EDM process—detecting signature of latent change to deleterious process in advance

Time series data of gap state were often used as feedback signal in EDM control systems. An effective way to quantify gap state in machining was developed in this paper. Based on a time series of gap states recording a machining process, the entire process was partitioned into three parts, transient process, efficient machining process, and deleterious process. It is expected that efficient machining process should be maintained long enough in consideration of machining efficiency and avoiding workpiece surface damage. In this case, a signature of structural change from efficient machining process to deleterious process has to be detected or detected in advance. It has been found that linear analysis methods failed the task. In this paper, a nonlinear analysis method, cross-prediction error, was employed to track this structural change in efficient machining process in two tests. In the first test, the efficient machining process was roughly split into 30 segments. By using the cross-prediction-error method in this test, the non-stationarity, a signature of structural change from stationary process in efficient machining process to non-stationary process, was successfully revealed in the last segment of the process. In another test, efficient machining process was even more finely split into 70 segments, and by using the cross-prediction-error method again it is found that the detected non-stationarity in the process was in the last segment but one. The second test not only proves the effectiveness of the method, but also brings forward the detected non-stationarity more than 10s. The detected non-stationarity in advance, thus, is supposed to be used for avoiding the occurrence of abnormal deleterious process and maintaining a persisted efficient machining process.     

Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors

Kinematic errors due to geometric inaccuracies in five-axis machining centers cause deviations in tool positions and orientation from commanded values, which consequently affect geometric accuracy of the machined surface. As is well known in the machine tool industry, machining of a cone frustum as specified in NAS979 standard is a widely accepted final performance test for five-axis machining centers. A critical issue with this machining test is, however, that the influence of the machine's error sources on the geometric accuracy of the machined cone frustum is not fully understood by machine tool builders and thus it is difficult to find causes of machining errors. To address this issue, this paper presents a simulator of machining geometric errors in five-axis machining by considering the effect of kinematic errors on the three-dimensional interference of the tool and the workpiece. Kinematic errors of a five-axis machining center with tilting rotary table type are first identified by a DBB method. Using an error model of the machining center with identified kinematic errors and considering location and geometry of the workpiece, machining geometric error with respect to the nominal geometry of the workpiece is predicted and evaluated. In an aim to improve geometric accuracy of the machined surface, an error compensation for tool position and orientation is also presented. Finally, as an example, the machining of a cone frustum by using a straight end mill, as described in the standard NAS979, is considered in case studies to experimentally verify the prediction and the compensation of machining geometric errors in five-axis machining.