Development of optical fiber Bragg grating force-reflection sensor system of medical application for safe minimally invasive robotic surgery

Force feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, the very long and stiff bars of surgical instruments greatly diminish force feedback for the surgeon. In the case of minimally invasive robotic surgery (MIRS), force feedback is totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peak force magnitude by at least a factor of two. Therefore, it is very important to provide force information in MIRS. Recently, many sensors are being developed for MIS and MIRS, but some obstacles to their application in actual medical surgery must be surmounted. The most critical problems are size limit and sterilizability. Optical fiber sensors are among the most suitable sensors for the surgical environment. The optical fiber Bragg grating (FBG) sensor, in particular, offers an important additional advantage over other optical fiber sensors in that it is not influenced by the intensity of the light source. In this paper, we present the initial results of a study on the application of a FBG sensor to measure reflected forces in MIRS environments and suggest the possibility of successful application to MIRS systems.     

穿刺针尖光纤力传感信号的小波变换分析

经皮软组织穿刺过程中,穿刺针尖会历经不同材料特性的器官组织,受到复杂变化的作用力。为了测量针尖处的作用力并鉴定穿刺路径上不同层次的软组织,研制了一种光纤力传感器,并进行了力信号分析。首先,基于法-珀干涉介绍了光纤力传感器的测量原理、光链路设计、及其与针的集成和标定方法。在穿刺力信号分析的基础上,提出利用Mallat算法对力信号进行小波变换,提取信号的特征模式,界定软组织的各层边界。最后,在猪的肝脏和肋条组织样本上进行了针穿刺实验验证。结果显示:光纤力传感器的可测力为0至3.20N,测量精度可达0.01N。得到的穿刺试验结果表明Mallat算法能够有效地区分软组织的类型。研制的光纤传感器满足穿刺力的测量范围、精度和可靠性等要求,所提出的小波变换算法可用于软组织边界的界定,有望用于机器人穿刺控制。     

全光纤钢制悬臂梁结构传感检测系统的研制

本文研制了基于马赫——曾德（Mech—Zehnder）干涉原理的全光纤传感检测系统，其优点是调节方便、性能稳定、抗干扰能力强。应用该系统在钢制悬臂梁结构上进行了静载应变检测和外加信号作用下的强迫振动检测，测量了该结构件的频率及振幅，其结果与同时进行的电测结果相近，说明光纤传感器用于结构件的振动测量是可靠的。本系统的研制也拓展了光测力学新方法，为实验教学提供了新的仪器。     

Influence of lamination process on optical fiber sensors embedded in composite material

In the paper we present the results of our research on optical fiber sensors embedded into composite material samples. We investigate the influence of the lamination process, axial orientation of an optical fiber sensor and coating of a fiber on stress monitoring of a composite material. In the paper we present two approaches to the case of composite condition monitoring, using a polarimetric fiber optic sensor as well as fiber Bragg gratings. We also present experimental evidence that interaction between a composite material and fiber optic sensors is very significant and depends on many factors such as fiber optic axial orientation and the coating layer surrounding an optical fiber.     

Experimental studies on fiber optic sensors embedded in concrete

Embedded fiber optic sensors are quite suitable for quantitative non-destructive long-term monitoring of concrete structures. Fiber optic sensors can be embedded in different types of structures, such as, buildings, roads, bridges, dams, etc. for monitoring different physical parameters like strain, temperature, deformation, etc. Bare fiber optic sensors are not suitable for directly embedding in concrete. Hence, some form of protective mechanism needs to be provided to the fragile fiber optic sensor for reliable performance. Suitable protective encapsulation to the bare sensor should ensure that there is no relative slip at the interface of the matrix concrete and the encapsulation. Investigations carried out to develop technique of embedding fiber optic sensor in concrete and performance evaluation of the developed embedment techniques are presented.     

工程结构光纤应变传感器

研究了一种用于土木工程结构监测的本征型强度调制光纤传感器。其敏感部分是利用光刻技术在多模光纤上形成的齿槽周期结构。文中对该传感器原理作了详细的分析，首次得到这种传感器既能测量拉应变，也能测量压应变的结论。传感器对应变的响应具有良好的线性和重复性，其应变灵敏度完全由敏感元件结构参数决定。文中给出了钢筋拉应变、混凝土压应变的试验，结果与理论一致，表明这种传感器是土木工程结构力学测量、结构监测等方面应用的新一代较为理想的光纤传感器     

基于应变传递理论的光纤传感器优化设计

联系传感器应用的作用机理,根据变形传递方式的不同,对工程中常用的光纤传感器进行了系统的归类分析。基于应变传递理论建立了应变传递系数与测量允许误差的关系,并以此为优化控制方程得到了满足工程测试精度要求的传感器最佳取值,给出了各类传感器具体的优化设计方法及优先设计指标。研究结果表明:基于应变传递理论的优化设计方法较适用于依靠界面剪应力传递变形的光纤传感器,其优先设计指标依次为粘贴(感知)长度、层间粘结强度、保护层弹性模量和半径、粘贴层厚度;端部扩径型传感器的优化设计则因其应变传递系数能较准确和便利地通过标定试验获取而不依赖应变传递理论,且无明显的优先设计指标。本文充分考虑了传感器工程应用的实际状态,以测试准确性为核心,从力学作用机理角度对传感器进行了较全面和系统的分析,其研究结果可以用于指导工程化光纤传感器的应用设计和标定测试。     

Pressure drop measurement in microfluidics channel by the Fabry-Perot diaphragm-based flow sensor

The measurement and control of pressure is an important parameter in optimizing flow rates in microfluidic channels. In this paper, we present simulation and experimental results of measuring pressure drop in a rectangular microfluidics channel by two Fabry-Perot (FP) flow sensors. Sensors include two circular diaphragms made of PDMS (Polydimethylsiloxane) with 50 μm thickness and 200 μm radius, located 2 cm apart which the surface of them create FP cavity with end surface of the fiber optic. Fabry-Pérot interferometers above two diaphragms measure the different deflections of the diaphragms caused by pressure changes in the micro channel. The fluid-structure interaction method is used to solve three-dimensional (3D) Navier-Stokes and continuity equations for selecting appropriate diaphragm thickness and validating experimental results. The experimental and theoretical results are in good agreement and according to the experimental results, these sensors have sensitivities of 30 (nm. (μL/min)^-1) and 10 (nm. (μL/min)^-1) without hysteresis and the resolution of the sensor is 33 nL/min.     

Development and sensing properties study of FRP-FBG smart stay cable for bridge health monitoring applications

There are many shortcomings in using traditional force sensors and bare optic fiber Bragg grating sensors (OFBGS) to monitor the stresses in bridge stay cables. In this paper, we propose to use the glass fiber with high durability and high intensity to embed the optic fiber grating sensor. First, the craft procedure of the GFRP-OFBGS and the layout methods among the bridge stay cables are described. Second, the sensing properties of the GFRP-OFBGS with different diameters were studied through experiments. Third, stretching experiments were carried out on the smart stay cables. The test results demonstrated that the whole procedure of the stretching test can be perfectly monitored, and the quantities of the cable tension can be recorded accurately. Finally, we investigated the craft procedure of the GFRP-OFBGS sensor layout in ErBian DaDu river bowstring arch in SiChuan province, China. The whole stretching procedure was successfully monitored during construction.     

一种新型的光纤电流传感器

本文提出了一种新颖的光纤干涉型电流传感器结构，分析其工作原理，导出其光路部分的数学模型，给出了实验结果，与法拉第磁光效应的光纤电流传感器相比较，该传感器能自动补偿光纤固有的双折射以及温度等环境变化产生的干扰；与一般干涉仪相比其工作动态线性范围扩大了数十倍，甚至数百倍。     

Development of an innovative plate dynamometer for advanced milling and drilling applications

Tool geometry optimization, workpiece material characterization, process monitoring and optimization are based on the measurement of cutting forces by using machining dynamometers. Commercial dynamometers cover a wide range of machining applications, nevertheless there is a lack of measuring devices suitable for investigating milling and drilling applications with relatively small cutters and high spindle speeds. In this work, the development and testing of an innovative plate dynamometer designed for this purpose is discussed. The new measuring system was based on three high-sensitive triaxial piezoelectric force sensors arranged in a novel triangular configuration. Component design was optimized by using FE numerical approaches, according to the general guidelines derived from mathematical modeling of sensor dynamics. The prototype of the proposed device was manufactured and experimentally tested against two high-end commercial plate dynamometers by performing static calibration, modal analysis and cutting tests. Experimental results proved the excellent characteristics of the new device and its effectiveness for investigating advanced machining applications.     

MEASURING THE SIX dof DRIVING POINT IMPEDANCE FUNCTION AND AN APPLICATION TO RB INERTIA PROPERTY ESTIMATION

An accurate driving point measurement is imperative in structural dynamic testing. For example, it is used to derive modal scaling, for experimental correlation of finite element models, impedance modelling and extracting the rigid body (RB) inertia properties of an object. A typical driving point measurement gives the linear force/displacement relationship at a single degree of freedom (dof), but any point on an object actually has rotational dofs as well. For example these rotational dofs must be measured in an impedance model where moments are transmitted at the connection point of two substructures. By ignoring the rotations, an inaccurate model will result. In the past, dynamic sensing technology has been limited to the accurate measurement of translational dofs. While rotational sensors do exist, their accuracy is called into question for certain applications. Rotational dofs have tended to be ignored in the measurement process. Applications, which require their use, such as impedance modelling and RB inertia property estimation, have suffered as a result. A process/sensor is being developed to accurately measure the driving point impedance function in all six dofs. The sensor as well as a calibration procedure will be presented here. In order to verify the validity of the calibration and measurement procedure, a new method for measuring the RB inertia properties of an object will be presented. This new method requires an accurate six dof driving point impedance measurement to provide accurate results. The inertia properties of an automotive brake rotor will be measured and compared with the results of a traditional pendulous swing test.     

虚拟指尖力传感器的建模与实现

为了在灵巧手动力学研究领域提供更多的研究工具，根据真实三维指尖力传感器的原理，运用力传感器弹性体建模的方法，构造了虚拟指尖力传感器的模型。为了求解力传感器模型的弹性体变形量，采用了一种动力学方程数值积分方法。该虚拟指尖力传感器，通过在机器人灵巧手虚拟现实遥操作平台上的运用，实现了对抓取滑动的判断，并验证了模型的精度。最后，基于滑动的判断，系统确定了一种抓取策略，针对虚拟环境中灵巧手的自主抓取问题进行了有益的探索。     

分布式光纤测温技术综述

光纤传感器以其独特的优点得到了人们的普遍关注,尤其分布式光纤传感技术在土木工程等大范围测量领域成为研究热点。通过对目前分布式光纤测温技术的系统论述,提出了分布式光纤测温技术的两个研究方向:基于光纤后向散射的光时域及频域反射技术的分布式光纤测温和基于光复用技术的光纤光栅分布式测温。通过对分布式光纤测温技术两个方向的工作原理、特点及性能的理论分析及仿真实验,综合论述和分析了分布式光纤测温技术两个方向的优点和缺陷,以及在具体工程中的实际应用。     

荧光原理的纸基张力传感器

针对穿戴应用中传统传感器的穿戴体验差、成本高、构造复杂等问题,本文将具有形变响应特性的荧光材料与纸张结合,构建出荧光压谱原理的新型光学无线张力传感器。传感器的敏感材料是由罗丹明B(RhB)与PDMS混合成的复合荧光材料薄膜,通过丝网印刷方式涂敷到美工纸带上。RhB的荧光特征随着施加在纸带上的张力而改变,在自制的力加载实验台上标定了该传感器的响应函数,在6 N量程里其张力分辨率可达0.04 N。借助手环和指套将该纸基张力传感器穿戴贴合于手部拇指关节,实验证实可测量手指的屈伸姿态。这是首款基于非波导特性的光学力敏可穿戴器件,具有柔性、亲肤、易回收、极低成本、几乎没有环境污染等显著优点,可作为即用即抛的消费级传感产品用于人体健康评估、关节康复锻炼效果评价和机器人姿态控制。     

Fiber optic displacement sensor with a large extendable measurement range while maintaining equally high sensitivity, linearity, and accuracy

This paper presents a fiber optic displacement sensor composed of a transmissive grating panel, a reflection mirror, and two optical fibers as a transceiver. The proposed fiber optic displacement sensor guarantees a stable reflected signal acquisition for application in real industrial fields. Through a parametric study of the grating pitch of the transmissive grating panel, the signal-to-noise ratio, linearity, resolution, accuracy error, and sensitivity of the proposed sensor were investigated. The measured bidirectional movement demonstrated a peak to peak accuracy of 10.5 μm, high linearity of 0.9996, resolution of 3.1 μm at the full bandwidth, signal-to-noise ratio of 27.7, and high sensitivity of 31.8 μm/rad during a movement of 16,004.0 μm using the transmissive grating panel, which had a grating pitch of 200 μm. Even for an extended measurement range, the proposed scheme enables the same accuracy, linearity, and sensitivity to be maintained when compared with conventional laser displacement sensors and fiber optic displacement sensors.     

车辆动态称重技术

随着公路运输业和商业贸易的发展，车辆动态称重技术已成为车辆载荷测量的关键技术和发展方向。文中对车辆动态称重系统的结构和弯板、压电传感器、单传感器及光纤传感器4种常用的动态称重传感器进行了介绍，并对系统产生的轴重信号进行了分析，重点讨论和研究了算术平均、神经网络、系统辨识等运用到车辆动态称重系统中的算法，并且阐述了今后的发展趋势。     

Compact optical fiber sensor smart node

We present a new optical fiber sensor interrogator specifically designed for an embedded instrumentation system. The proposed system consists of a super luminescent diode as a broadband source, a high speed tunable micro-electro-mechanical system (MEMS) filter, photodetector, and an integrated microprocessor for data aggregation, processing, and communication. The entire system is integrated together in a compact package to create a fiber "smart" sensor. The system is capable of interrogating a variety of multiplexed fiber sensors, processing the data, and communicating the results digitally. As an example, the system has been calibrated with an array of fiber Bragg grating sensors.     

A review of previous studies on the applications of optical fiber sensors in geotechnical health monitoring

In recent decades, conventional electric instruments have already been widely used to monitor the performance of geotechnical structures. However, there are several inherent limitations of electric instruments for engineering including: electromagnetic interference, a large number of cables for multipoint measurement, signal loss in long distance transmission, and poor durability. Since the first Fiber Bragg Grating (FBG) sensor was fabricated in 1978, a significant progress has been made on the commercialization of optical fiber sensing technologies. In 1980s, a fully distributed sensing technology named Brillouin Optical Time Domain Analysis (BOTDA) has been proposed and developed for measuring strain and temperature. In this paper, the authors review previous studies on the development and application of fiber optic sensors. Based on the measured strains, various analysis methods were transferred to required parameters such as displacement, force and pressure which can more directly reflect the safety of geotechnical structures under complex engineering stress condition.     

Optimization of the frequency-modulated continuous wave technique for referencing and multiplexing intensity-based fiber optic sensors

In this paper, we demonstrate the interrogation of fiber optic intensity sensors by using the combination of the frequency-modulated continuous wave concept with the spectral selective reflectivity of fiber Bragg gratings. Thus, we multiplex these kinds of sensors with this technique having simultaneously a referenced system. The basis of this dual functionality is described and results are presented for the case of interrogation of two multiplexed intensity sensors. Their evaluation permits to establish the conditions to address a sensor network of this type. Also, it is proposed a strategy to implement this sensing approach without the requirement of using optical fiber delay lines in the sensor heads.