斜尖针穿刺软组织建模及针尖轨迹预测

在经皮穿刺过程中,当带斜尖的针穿刺软组织时,针与其周围组织相互作用,导致针体产生弯曲变形,针尖偏离预定方向,进而直接影响穿刺手术的定位精度。将针穿刺软组织的过程视为准静态过程,并进行离散化,建立针-组织相互作用模型。在该模型中,考虑到软组织的非线性与各向异性,将针视为由一系列非线性弹簧支撑的悬臂梁,且各点的弹簧刚度彼此不同。建立针-组织相互作用中的摩擦力及切割力模型,借助于穿刺实验,将穿刺力分解为摩擦力和切割力,进而获得力模型中的各个参数。基于虚拟非线性弹簧模型和穿刺力模型,根据最小势能原理,采用瑞利-里兹法预测针的偏转,进而获得进针过程中针尖的轨迹。仿真及实验结果表明,该模型能够精确地预测针尖位置,为穿刺路径规划提供理论依据。     

Mallat算法的光学实现方法

现有的光学小波变换方法均基于连续小波变换,基于离散信号的小波变换算法（Mallat算法）的光学小波变换还没有出现,这阻碍了光学小波变换应用的发展。针对这一问题,分析利用光学4f系统实现Mallat算法的基本原理,提出Mallat算法的光学实现方法。针对空间光调制器只能实现非负的实函数,且CCD只能记录光的强度,给出一种应用于光学4f系统的光学小波滤波器的设计方法。使用该种光学小波滤波器,利用光学4f系统实现Mallat算法的小波分解部分,并通过数值计算实现Mallat算法的小波重构部分。仿真分析和光学实验结果验证了方法的正确性。     

基于图形显示算法的小波变换在机械故障诊断中的应用研究

针对广泛应用的Mallat快速算法在小波变换中存在的随分解层数增大数据长度成倍减小,使得对信号进行精细分析、提取微弱故障信息受到限制的问题,研究应用图形显示算法与Mallat算法相结合解决这一问题的方法。介绍了图形显示算法的基本原理,推导了正交小波的图形显示算法。给出了应用该算法对斜轴式柱塞泵振动信号进行分析,在强振动背景下提取微弱故障特征的实例。方法可有效地用于信号的深层信息处理和微弱故障信息的提取。     

大量程柔性铰六维力传感器静态解耦的研究

为提高大量程六维力传感器的测量精度,提出了一种新型的六维力传感器非线性静态解耦方法,该方法结合混合递阶遗传算法和小波神经网络的优点,采用递阶遗传算法与最小二乘法分别对小波神经网络隐层结构参数以及输出层权值进行优化,再将优化后的小波神经网络模型用于六维力传感器非线性解耦.建立了基于混合递阶遗传算法和优化小波神经网络的六维力传感器非线性解耦模型,设计了基于混合递阶遗传算法的小波神经网络结构及参数优化算法,给出了六维力传感器非线性解耦的具体实现流程.以最新研制的6-UPUR大量程柔性铰六维力传感器为对象进行实验,结果表明,采用该方法六维力传感器的Ⅰ类误差和Ⅱ类误差分别为1.25％和2.59％,比采用BP和RBF神经网络方法的测量精度高.     

用小波变换提高散斑能见度光谱测量法的灵敏度

在分析被动层颗粒温度含噪特点的基础上模拟了低信噪比的方波信号,根据变化规律,采用Mallat快速算法分析低信噪比的方波信号,并根据噪声分布特性设计了用于抑制被动层颗粒温度中干扰噪声的算法。对所设计算法进行仿真实验,结果表明,该算法可以最大限度地滤除信号中的噪声。通过搭建滚筒实验装置,测量滚筒被动层的颗粒温度,对测量数据进行分析,有效地测出了内部颗粒温度状态变化,表明了小波变换能有效提高测量被动层颗粒温度的信噪比。     

一种新的实时小波分析

叙述了多分辨分析的定义后 ,分析了Mallat塔式算法的特点及不能用于实时分析的不足。针对Mallat算法的结构及小波函数有限支撑的特点 ,提出了对Mallat算法进行改进的垒墙式算法。新算法的信号处理不再是自底至顶进行 ,而是按信号顺序进行 ,从而可实现信号的实时处理。     

自由曲面数控加工中刀具破损的小波分析

介绍了小波变换的特点,并将其与傅立叶变换及快速傅立叶变换进行了对比,结合刀具破损信号,分析了快速小波变换——Mallat算法.对自由曲面数控加工中主轴电机电流信号的提取技术进行了分析,指出了霍尔电流传感器是行之有效的方法.鉴于刀具破损电机电流信号的瞬时性,采用小波分析方法给出了提取刀具破损信息特征的成功应用实例.研究表明,多分辨(多尺度)分析的方法,对于刀具破损这种突变信号不但具有精确的时-频定位作用,还具有易于监测的优点,说明这种方法能够有效地应用于刀具破损监控的信号处理.     

基于小波分析的齿轮故障诊断方法的研究

主要研究了小波变换中小波的Mallat算法,并将其应用到齿轮的故障诊断之中,对微弱机械振动信号进行分析.有效地完成了微弱信号的提取,对故障特征信号进行了时域定位,试验结果表明了该分析方法的有效性.     

基于小波分析的齿轮故障诊断方法的研究

主要研究了小波变换中小波的Mallat算法,并将其应用到齿轮的故障诊断之中,对微弱机械振动信号进行分析.有效地完成了微弱信号的提取,对故障特征信号进行了时域定位,试验结果表明了该分析方法的有效性.     

小波分析在模拟电路故障特征提取中的应用

针对模拟电路故障特征提取,提出了在小波变换Mallat算法的基础上,结合快速傅里叶变换的方法.该方法选用dbN小波,利用Mallat算法将信号分解,得到一系列高频和低频子带,分别对各子带进行快速傅里叶变换,从而得到各子带上信号的频谱.文章给出了采用该方法的基本步骤和应用实例,应用表明该方法可以有效辨别模拟电路参数型故障,准确得到故障特征.     

Dynamic soft tissue deformation estimation based on energy analysi

The needle placement accuracy of millimeters is required in many needle-based surgeries. The tissue deformation, especially that occurring on the surface of organ tissue, affects the needle-targeting accuracy of both manual and robotic needle insertions. It is necessary to understand the mechanism of tissue deformation during needle insertion into soft tissue. In this paper, soft tissue surface deformation is investigated on the basis of continuum mechanics, where a geometry model is presented to quantitatively approximate the volume of tissue deformation. The energy-based method is presented to the dynamic process of needle insertion into soft tissue based on continuum mechanics, and the volume of the cone is exploited to quantitatively approximate the deformation on the surface of soft tissue. The external work is converted into potential, kinetic, dissipated, and strain energies during the dynamic rigid needle-tissue interactive process. The needle insertion experimental setup, consisting of a linear actuator, force sensor, needle, tissue container, and a light, is constructed while an image-based method for measuring the depth and radius of the soft tissue surface deformations is introduced to obtain the experimental data. The relationship between the changed volume of tissue deformation and the insertion parameters is created based on the law of conservation of energy, with the volume of tissue deformation having been obtained using image-based measurements. The experiments are performed on phantom specimens, and an energy-based analytical fitted model is presented to estimate the volume of tissue deformation. The experimental results show that the energy-based analytical fitted model can predict the volume of soft tissue deformation, and the root mean squared errors of the fitting model and experimental data are 0.61 and 0.25 at the velocities 2.50 mm/s and 5.00 mm/s. The estimating parameters of the soft tissue surface deformations are proven to be useful for compensating the needle-targeting error in the rigid needle insertion procedure, especially for percutaneous needle insertion into organs.     

Dynamic Soft Tissue Deformation Estimation Based on Energy Analysis

The needle placement accuracy of millimeters is required in many needle-based surgeries. The tissue deformation, especially that occurring on the surface of organ tissue, affects the needle-targeting accuracy of both manual and robotic needle insertions. It is necessary to understand the mechanism of tissue deformation during needle insertion into soft tissue. In this paper, soft tissue surface deformation is investigated on the basis of continuum mechanics, where a geometry model is presented to quantitatively approximate the volume of tissue deformation. The energy-based method is presented to the dynamic process of needle insertion into soft tissue based on continuum mechanics, and the volume of the cone is exploited to quantitatively approximate the deformation on the surface of soft tissue. The external work is converted into potential, kinetic, dissipated, and strain energies during the dynamic rigid needle-tissue interactive process. The needle insertion experimental setup, consisting of a linear actuator, force sensor, needle, tissue container, and a light, is constructed while an image-based method for measuring the depth and radius of the soft tissue surface deformations is introduced to obtain the experimental data. The relationship between the changed volume of tissue deformation and the insertion parameters is created based on the law of conservation of energy, with the volume of tissue deformation having been obtained using image-based measurements. The experiments are performed on phantom specimens, and an energy-based analytical fitted model is presented to estimate the volume of tissue deformation. The experimental results show that the energy-based analytical fitted model can predict the volume of soft tissue deformation, and the root mean squared errors of the fitting model and experimental data are 0.61 and0.25 at the velocities 2.50 mm/s and 5.00 mm/s. The estimating parameters of the soft tissue surface deformations are proven to be useful for compensating the needle-targeting error in the rigid needle insertion procedure, especially for percutaneous needle insertion into organs.     

Effect of elastomer characteristics on fiber optic force sensing performance in biomedical robotics applications

Miniaturized and “smart” sensors are required for research in biology, physiology, and biomechanics, and they have extremely important clinical applications for diagnostics and minimally invasive surgery. Fiber optic sensors have been proven to provide advantages compared to conventional sensors and high potential for biomechanical and biomedical applications. They are small, easy to operate, minimally invasive with low risk, more accurate, and inexpensive. This paper reports the design and modeling of a fiber optic force sensor that is capable of measuring compliance for a contact force of up to 1 N. The main objective of this study is to design and model a fiber optic sensor capable of measuring the total force applied on an object. A polydimethylsiloxane (PDMS) elastomer film with a thickness of 1.2 mm is placed between an optical fiber tip and an object, and it is used for measuring the force applied on a rigid element. The compliance of the fiber optic force sensor is measured by recording the response of PDMS elastomer films under different load conditions. We use finite element modeling results as a basis for comparing experimental data. The agreement between theoretical predictions and experimental data is reasonable and within an acceptable range.     

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。     

Design and evaluation of a novel biopsy needle with hemostatic function

Biopsy is a method commonly used for early cancer diagnosis. However, bleeding complications of widely available biopsy are risky for patients. Safer biopsy will result in a more accurate cancer diagnosis and a decrease in the risk of complications. In this article, we propose a novel biopsy needle that can reduce bleeding during biopsy procedures and achieve stable hemostasis. The proposed biopsy needle features a compact structure and can be operated easily by left and right hands. A predictive model for puncture force and tip deflection based on coupled Eulerian–Lagrangian (CEL) method is developed. Experimental results show that the biopsy needle can smoothly deliver the gelatin sponge hemostatic plug into the tissue. Although the hemostatic plug bends, the overall delivery process is stable, and the hemostatic plug retains in the tissue without being affected by the withdrawal of the needle. Further experiments indicate that the specimens are well obtained and evenly distributed in the groove of the outer needle without scattering. Our proposed design of biopsy needle possesses strong ability of hemostasis, tissue cutting, and tissue retention. The CEL model accurately predicts the peak of puncture force and produces close estimation of the insertion force at the postpuncture stage and tip position.     

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.     

光纤压力传感器在流体压力测试中的应用

介绍了光纤压力传感器的工作原理和特点；对其在流体压力测试中的应用理论和实践进行了研究和探索。     

Contributions in medical needle technologies—Geometry,mechanics, design,and manufacturing

This article summarizes the contributions in research on tissue cutting with needles. The geometry of the needle's cutting edges was analytically defined and expressions for the inclination and rake angles of hollow and solid needles and trocars have been derived. Based on the semi-empirical method, finite element model and the fracture mechanics approach, force models of needle insertion were developed. The relationship between the needle's tip geometry and insertion force was established and used in several applications. It was shown, for example, that the cutting edge of the lancet needle can be optimally designed to minimize insertion force or bevel length. The cutting mechanics in rotary needle insertion was investigated along with the exploration of improvements of needle biopsy performance by decreasing the needle cutting and friction forces. The deflections of the needle during insertion were measured to develop a strategy for guiding the needle to the right position in brachytherapy and drug delivery. From an overall perspective, fundamental advances and application problems based on the cutting mechanics of soft tissue for needle were highlighted to lay the foundation for developments of biomedical device and improvements of healthcare procedures.     

前列腺高精度穿刺机理及策略研究

针介入前列腺中,前列腺会产生漂移、变形以及针尖会产生偏转等问题。为了改善机器人操控穿刺针的定位精度,研究了振动、旋转穿刺软组织机理,建立针-前列腺相互作用力模型。利用制备的实验平台分别完成了振动穿刺和旋转穿刺效果评估实验;通过对上述实验结果的分析,提出了一种基于振动和旋转的高精度进针策略,并设计了相应的进针策略控制软件;最后,采用高精度进针策略完成了穿刺力评估实验,实验结果验证本文进针策略的有效性。     

High temperature and force measurements using a type II cascaded regenerated fiber Bragg grating (RFBG)

Abstract

A Type II-IR (infrared) grating cascaded with a regenerated fiber Bragg grating (RFBG) is described for force measurements at high temperature. The sensor was fabricated by fusion splicing a Type II grating with a Type I seed grating that was subjected to isothermal annealing in order to obtain the RFBG. Due to the different responses to temperature and force, these parameters were determined by measuring the reflection peak of the Type II grating and RFBG. The experimental results indicate that the sensor may be used for simultaneous measurement of temperature and force from 250?°C to 500?°C and 0.003?N to 0.797?N.