一种基于PCB工艺的平面绝对式角位移传感器研究

文中研究的平面绝对式角位移传感器采用PCB工艺制造定子和转子。定子PCB包含正弦形平面激励线圈和环形感应线圈,转子PCB包含改变激励线圈和感应线圈耦合系数的铜箔阵列。传感器共有2个传感通道,2个通道的重复结构周期数相差为1,共同实现绝对角位移测量。文中对该传感器进行了有限元仿真,验证了其原理可行性。样机实验表明,在0°～360°范围内传感器的原始测量误差为-104.2″～28.8″。这种基于PCB工艺的平面绝对式角位移传感器,具有结构简单、厚度小的特点,非常适合机器人关节臂等对传感器体积要求苛刻的工作场合。     

基于平面线圈的高分辨力时栅角位移传感器

针对现有时栅角位移传感器采用漆包线绕制工艺加工线圈,导致线圈布线不均且容易随时间发生变化进而影响测量精度的问题,提出一种基于PCB技术的新型时栅角位移传感器。该传感器通过在PCB基板的不同层上布置特定形状的激励线圈和感应线圈,形成两个完全相同并沿圆周空间正交的传感单元;当在两传感单元的激励线圈中分别通入时间正交的两相激励电流后,通过导磁定子基体和具有特定齿、槽结构的导磁转子对传感单元内的磁场实施精确约束,使两传感单元的感应线圈串联输出初相角随转子转角变化的正弦感应信号;最后通过高频时钟脉冲插补初相角实现精密角位移测量。利用有限元分析软件对传感器进行了建模和仿真。根据仿真模型制作了传感器实物,开展了验证实验,并对实验中角位移测量误差的频次和来源进行了详细分析。经过标定和补偿,最终获得了整周范围内误差在-2.82″~2.02″的时栅角位移传感器。理论推导、仿真分析和实验验证均表明,该传感器不仅能实现精密角位移测量,还能在激励线圈和感应线圈空间极距和信号质量不变的情况下,将位移测量的分辨力从信号源头提高1倍,且结构简单稳定、极易实现,特别适用于环境恶劣的工业现场。     

基于电涡流的多周期双极直线位移传感器

传统的基于电涡流的多周期位移传感器由于输出信号的周期重复性,难以解决断电重启后的绝对位置识别问题。 提出 一种基于电涡流的新型双极直线位移传感器。 经过理论与仿真分析,验证了随着滑片的滑动,接收线圈中感应电压的幅值呈现 正余弦变化。 设计了双极敏感结构,通过上极多周期接收线圈保证位移的精确测量。 下极布置单周期接收线圈对上级所处周 期进行识别。 通过感应信号偏移及幅值归一化处理算法提高精度,在实验室搭建传感器样机,以高精度电控平移台进行测试。 经测试,新型多周期双极电涡流直线位移传感器可以实现绝对位置测量,在 0~ 60 mm 量程内测量误差为 30 μm,最大非线性为 0. 08% 。 突破了传统多周期涡流式位移传感器绝对位置无法识别的局限。     

电感式磨粒传感器中铁磁质磨粒特性仿真研究

针对机械装置的在线监测传感器,模拟了铁磁质磨粒通过传感器过程中传感器线圈的磁场和感应线圈的感应电压瞬态变化特性.考虑了线圈与铁磨粒的材料、线圈匝数和激励线圈的输入电压等因素,应用Jmag Designer I0.4软件建立了传感器的二维有限元模型.仿真结果揭示了磨粒运动过程中线圈磁场与感应线圈中感应电压的变化规律,获得了感应电压与球形磨粒的直径大小的立方成正比,与磨粒运行速度成正比.研究结果对于电感式磨粒传感器的开发具有重要的指导价值.     

油液磨粒检测传感器线圈间距对输出信号的影响

电感式磨粒传感器在机械设备润滑油液磨粒在线监测中具有独特优势,通过测量传感器输出的感应电压信号来获取油液中磨粒的大小、数量以及质量等信息,进而可实现设备磨损程度的判断。为了研究电感式三线圈传感器中相邻两线圈之间的距离对传感器输出感应信号的影响,基于差动式三线圈互感原理建立传感器三维模型;利用JMAG-Designer12.0软件对传感器检测铁磁磨粒的过程进行瞬态电磁仿真,分析线圈间距对传感器输出感应电动势的影响;通过制作传感器进行实验并行验证仿真结果的正确性。研究结果表明,当线圈间距小于2.5 mm时,感应电动势随间距的增加而增大,当线圈间距大于2.5 mm时,感应电动势随间距的增加而减小,线圈间距为2.5 mm时,感应电动势最大,传感器输出信号与理论正弦信号变化趋势接近一致,并且信号干扰最小、信号最为稳定。     

电感式角度传感器电磁耦合敏感元件的研究

针对传统角度传感器结构复杂、制造成本高,且不易于嵌入式安装等不足,设计研究了一种基于PCB板的平面电感式角度传感器上的电磁耦合敏感元件。分析了此电感式角度传感器的实现机理,根据实现机理,建立了理论模型;在ANSYS Maxwell软件中创建了激励线圈、接收线圈和转子的实体模型,并进行了电磁耦合仿真分析,仿真结果验证了设计的合理性与可行性。根据理论模型制作原型敏感元件,在角度传感器实验台上进行电磁耦合实验,得到转子转动角度与接收信号峰峰值变化的对应关系,分析其影响因素。改进设计,对改进型敏感元件进行电磁耦合实验,实验结果表明改进型敏感元件提高了角度检测的灵敏度,3组接收信号峰峰值变化曲线中间部分线性度良好,且能完整覆盖一个变化周期。     

花萼状涡流传感器及其飞机金属结构疲劳损伤监测试验研究

飞机金属结构疲劳损伤的实时在线监测,对于保证飞行安全是极其重要的。在文献[13]的基础之上,提出一种花萼状涡流传感器,并搭建基于该传感器的疲劳裂纹监测系统,进行程序载荷谱下的2A12-T4铝合金拉伸疲劳试验件的疲劳损伤在线监测试验,通过对比传感器监测结果和疲劳裂纹断口定量分析结果,对传感器的疲劳裂纹定量监测能力进行验证。监测试验结果与试件断口定量分析对比结果表明,在试件疲劳裂纹扩展过程中,传感器的各感应线圈通道的幅值比信号的变化较为明显,同时具有阶跃特征,当裂纹从一个感应线圈通道位置扩展至其相邻通道位置时,该感应线圈通道的幅值比信号会急剧增加,而当裂纹穿出其相邻通道位置时,该感应线圈通道的幅值比信号增加速度显著减缓;根据阶跃特性,将各感应线圈通道的幅值比信号开始快速增加的"拐点"作为裂纹前缘进入相应感应线圈通道的特征,花萼状涡流传感器可以实现疲劳裂纹的定量监测,监测精度为1 mm;离疲劳源较近的感应线圈通道的幅值比信号可定性监测结构的疲劳累积损伤程度。     

基于有限元仿真的涡流探头特性研究

涡流检测在工业生产及设备运行维护等无损检测技术领域占有重要地位。文中介绍一种用于无损检测的涡流探头,探头由1个激励线圈与2个接收线圈组成。激励线圈在电压信号的激励下,在试件中产生感应涡流,试件中涡流随缺陷发生变化,接收线圈捕获到涡流产生磁场的变化,以此分辨试件表面缺陷。分别对涡流探头的激励线圈、接收线圈进行理论分析,使用有限元仿真软件Maxwell对传感器进行建模与仿真。采用数值方法分析探头在正弦波电压激励下的工作方式,铝试件与Q235试件表面涡流分布与探头输出特性。仿真分析了涡流效应对Q235材料探头输出的影响。对Q235试件中不同缺陷深度对探头输出电压大小的影响进行了分析。根据仿真结果,进行了探头实物制作,获得了探头在不同缺陷深度的输出信号,通过实验验证了探头对缺陷检测的有效性。     

高灵敏低压电磁感应式滑油磨屑传感器

提出了一种高灵敏低压低功耗的三线圈电磁感应式磨屑检测方法。理论推导了金属磨屑穿过线圈组引起的感应电压变化的表达式,并据此对线圈组的几何参数进行了优化。通过在激励和感应线圈两端分别并联和串联恰当容值的电容实现双LC谐振,以获得更高的激励电流和感应电压。实验验证了在108 kHz、5 Vpp的正弦信号激励下,上述两种方法同时使用能够较大幅度提高信噪比,在相敏检波电路之后未使用放大电路的情况下能够清晰地检测到低至150μm的铁质颗粒,而此时激励线圈的有功功率仅为1.12 mW。所设计的传感器能够在平衡低功耗的同时获得高灵敏度,其优化思路对于同类型传感器优化具有借鉴意义。     

磁悬浮轴承横向磁通传感器设计与分析

横向磁通传感器因结构紧凑和高检测精度在磁悬浮轴承系统中具有广阔的应用前景。 随磁悬浮轴承技术的发展,对横 向磁通传感器的检测性能提出了更高要求。 为进一步提升横向磁通传感器的性能,满足磁悬浮转子高精度位移监测需求,本文 针对灵敏度指标对传感器进行设计与分析。 通过建立传感器的数学模型和电磁场有限元分析,研究了激励频率和线圈参数之 间的关系。 对传感器线圈匝数与灵敏度的相关性进行了数值研究,从检测转子的角度分析了趋肤效应对传感器灵敏度的影响。 设计了传感器信号处理电路实现由位移信号到电压信号的转换,并搭建实验平台对传感器的输出特性进行测量。 实验结果表 明,当灵敏度为 20 mV/ μm、检测范围为±500 μm 时,传感器的线性度为 0. 69% ,且具有良好的动态特性,适用于磁悬浮轴承系 统的转子高精度径向位置检测。     

面向超高场核磁共振应用的微型接收线圈制作与实验研究

为实现纳升级微量样品检测,结合商业常规核磁共振3.2毫米探头,本文研究了两种类型的自谐振微型接收线圈。当无线传输能量时,探头螺旋管形成射频脉冲激励能量。而微型接收线圈对该能量进行接收后以样品为作用目标,并采集信号回传,把感应获取的磁共振信号传输到探头螺线管。与现有磁共振探头不同,本文提出Pigtail型和Stripline型微接收线圈结构。实测结果显示,线圈谐振频率达128MHz和935.7MHz,应用于3T超导核磁共振设备初步完成了蔗糖波谱的测试分析实验,表明微型接收线圈对提高谱线分辨率有重要作用。     

Fabrication and characterization of a new MEMS fluxgate sensor with nanocrystalline magnetic core

This paper presents a new MEMS fluxgate sensor with a Fe-based nanocrystalline ribbon magnetic core and 3D micro-solenoid coils. The excitation coils were placed vertically to the sensing coil on the chip plane. Second harmonic operation principle was adopted in this fluxgate sensor. The total size of the fluxgate sensor was 6.25 mm × 4.85 mm × 120 μm. A simple testing system was established to characterize the fabricated devices. A band pass filter was used to pick up the second harmonic signals in the sensing coils. When excitation rms current of 120 mA and the operational frequency of 200 kHz were selected for the testing of the fabricated devices, the sensitivity of the developed fluxgate sensor was 1005 V/T in the linear range of −500 μT to +500 μT. Due to the combination of the 3D structure coils with the nanocrystalline core, relatively low sensor noise was achieved. The noise power density was 544 pT/Hz^0.5@1 Hz and the noise rms level was 9.68 nT in the frequency range of 25 mHz-10 Hz.     

光电轴角编码器光电信号正交性偏差的相量校正方法

高精度光电轴角编码器中的细分是误差的主要来源,而细分误差中莫尔条纹光电信号的正交性偏差影响最大。采用相量校正方法对正交性偏差进行校正,实现电路简单,校正效果十分明显。以正弦信号为基准信号,而将余弦信号分解为0°和90°两个正交分量,0°分量就是产生正交性误差的原因,通过补偿掉该分量,即可基本消除正交性误差。为进一步减小细分误差,通过精密调节,使余弦信号的幅值与正弦信号严格相等,将正弦及其反相信号与余弦信号分别相量相加可得到严格正交的两个新相量,从而消除正交性误差。实验结果表明,经精密相位校正后,正交性偏差从1″降低到0.1″左右。     

Resonant enhancement of a passive coil-capacitance loop in eddy current sensing path

A passive resonant coupling loop was composed by connecting an inductive coil with a capacitance element in series. Without any electric connection with measurement circuits, the loop is coaxially inserted into the sensing path between the sensing coil and metallic target of an eddy current proximity sensor. When the sensor is working around the natural frequency of the resonant loop, the mutual coupling between the sensing coil and metallic target is efficiently improved. Home-made eddy current proximity sensing coils are experimentally tested in frequencies around 800 kHz. The results indicate that the equivalent inductance of the sensing coil performs more sensitively to metallic target distance. Thus the higher sensitivity and resolution of proximity sensor will be expected.     

超导转子旋转驱动装置设计

设计了一种基于迈斯纳效应的超导转子旋转驱动装置,利用驱动装置的定子线圈产生的磁场在空心转子内壁窗口产生的转动力矩驱动转子旋转。对超导转子旋转驱动力进行了有限元分析,结果表明,驱动力矩近似与驱动电流的平方成正比。在4.2 K温度、30 Pa气压下进行了转子旋转实验,30 A驱动电流下转子转速达到了8512 r/min。实验结果为进一步优化装置运行参数及提高转子旋转稳定性奠定了基础。     

Analysis and comparison of the performance of MEMS fluxgate sensors with permalloy magnetic cores of different structures

This paper presents four MEMS fluxgate sensors which were fabricated with same processes but with magnetic cores of different structures. Thick photoresist-based UV lithography and electroplating were adopted in the fabrication of the fluxgate sensors. Solenoid coils used as excitation and sensing elements were made of copper, whereas the magnetic core material was permalloy. Polyimide was used to support the structures of the sensors. An electronic testing system based on the second harmonic principle was established to characterize the fabricated devices. Each sensor was tested with the excitation coils being excited by a sine waveform current whose frequency was 100 kHz. From these experiments we can obtain some information about how the magnetic core structures affecting the magnetic field measuring performance of the fluxgate sensors, which might make some contribution to the performance improvement and miniaturization of fluxgate sensors.     

GMR array uniform eddy current probe for defect detection in conductive specimens

The usage of eddy current probes (ECP) with a single magnetic field sensor represents a common solution for defect detection in conductive specimens but it is a time consuming procedure that requires huge amount of scanning steps when large surface specimens are to be inspected. In order to speed-up the nondestructive testing procedure, eddy current probes including a single excitation coil and an array of sensing coils present a good solution. The solution investigated in this paper replaces the sensing coils for giant magneto-resistors (GMRs), due to their high sensitivity and frequency broadband response. Thus, the ECP excitation coil can be driven at lower frequencies than the traditional ones allowing defects to be detected in thicker structures.In this work an optimized uniform eddy current probe architecture including two planar excitation coils, a rectangular magnetic field biasing coil and a GMR magnetometer sensor array is presented. An ac current is applied to the planar spiral rectangular coil of the probe, while a set of GMR magnetometer sensors detects the induced magnetic field in the specimens under test. The rectangular coil provides the DC uniform magnetic field, assuring appropriate biasing of the GMR magnetometers of the probe, setting-up the functioning point on the linear region and at the same branch of the GMR static characteristics. The differences on the images obtained for the same specimen for each GMR are reduced if all sensors are biased on the same working point. Elements of the automated measurement system used to inspect the plate under test using the proposed eddy current probe, including a validation procedure based on a 2D template matching algorithm and the corresponding experimental results are included in the paper.     

Liftoff insensitive thickness measurement of aluminum plates using harmonic eddy current excitation and a GMR sensor

This paper describes the implementation of a device that measures the thickness of metallic plates. A pancake coil for magnetic field sinusoidal excitation is used and detection is performed with a bridge giant magneto-resistor sensor. The paper uses the theory of the linear transformer to explain the liftoff effect with a special attention to the point of interception phenomenon. The transformer model shows that to attain the interception points with instantaneous measured voltages independent of the liftoff gap the excitation coil must be driven with imposed current. This effect was explored to show that a simultaneous process of thickness and conductivity measurement is feasible.