复杂超声场测量和建模方法的研究

发布时间：2018-04-16 04:00

本文选题：超声换能器 + 超声场测量　；参考：《兰州大学》2015年硕士论文

【摘要】：医用超声换能器是生物医学超声工程技术中的重要组成部分。如何对医用换能器的声场特性和频率特性进行测量分析,一直都是技术研究的重点。随着科技的进步,在实际的医学应用中,超声设备经历了由单个换能器独立工作,到多振元换能器联合使用工作的过程。为了满足对复杂超声场测量和建模的要求,本文利用一套超声场自动化测量和分析系统,对复杂超声场进行测量,并推导出复杂超声场声压分布的理论模型。本实验中所用的超声场自动化测量和分析系统,是实验室在经过综合研究后,自行研制开发的。机械运动方面以步进电机作为驱动,使搭载水听器的机械人能够在水槽中沿X轴、Y轴和Z轴方向进行直线扫描。在LabVIEW平台,实现了声场的单轴声场扫描、三维声场扫描等测量程序,以及对所采集数据进行实时保存和数据分析的声场回放程序,将复杂超声场在程序中进行重建。数据以图形的方式显示,结果更加的直观明显,对换能器性能的评估与检测也更加的方便。本文实验所用换能器的中心频率分别为1.5MHz、1.0MHz。保持实验环境一致,待信号稳定输出后,先对单个自聚焦换能器进行声场特性和频率特性的测量,将测量结果与理论模型进行对比分析,在焦点位置,声压的实际测量值和理论值相比,误差率为1.4%,证实了本套自动化测量和分析系统在声场扫描方面的准确性。然后设计并实现了用于测量由两个换能器组成的复杂声场的实验水槽,编写相关LabVIEW测量程序。再根据空间内坐标转换的原理,将空间内任意一点分别在不同换能器的坐标系中进行表示,并将两换能器在该点处的的声压值进行叠加,推导出复杂超声场重建的理论模型。利用本套自动化测量和分析系统,对实验中的复杂声场进行测量,经过多次实验,在焦点位置,声压的实际测量值和理论值相比,误差率为2.9%,声功率的实际测量值和理论值相比,误差率为4.5%,验证了理论模型正确性。利用该理论模型,为复杂超声场的测量提供有效的理论基础,为超声换能器的检测和评估,提供了新的思路和方法。
[Abstract]:Medical ultrasonic transducer is an important part of biomedical ultrasonic engineering technology.How to measure and analyze the characteristics of sound field and frequency of medical transducers has always been the focus of technical research.With the development of science and technology, ultrasonic equipment has gone through the process of working independently from a single transducer to a combined use of a multi-vibration transducer in practical medical applications.In order to meet the requirements of measurement and modeling of complex ultrasonic field, a set of automatic ultrasonic field measurement and analysis system is used to measure the complex ultrasonic field, and the theoretical model of sound pressure distribution in complex ultrasonic field is deduced.The automatic measurement and analysis system of ultrasonic field used in this experiment was developed by the laboratory after comprehensive research.In the aspect of mechanical motion, the stepper motor is used to drive the hydrophone robot to scan straight line along the X axis Y axis and Z axis in the water tank.On the LabVIEW platform, the measurement programs such as uniaxial sound field scanning, 3D sound field scanning, and sound field playback program for real-time storage and data analysis of the collected data are realized. The complex ultrasonic field is reconstructed in the program.The data are displayed graphically, the results are more visual and obvious, and it is more convenient to evaluate and detect the performance of the transducer.The central frequencies of the transducers used in this paper are 1.5 MHz and 1.0 MHz, respectively.After the steady output of the signal, the sound field and frequency characteristics of a single self-focusing transducer are measured, and the measured results are compared with the theoretical model, and the results are compared with the theoretical model.Compared with the theoretical value, the error rate of the sound pressure measurement is 1.4, which proves the accuracy of the automatic measurement and analysis system in acoustic field scanning.Then the experimental tank for measuring the complex sound field composed of two transducers is designed and implemented, and the related LabVIEW measurement program is written.According to the principle of coordinate transformation in space, any point in the space is represented in the coordinate system of different transducers, and the sound pressure values of the two transducers at this point are superposed, and the theoretical model of complex ultrasonic field reconstruction is deduced.Using this automatic measurement and analysis system, the complex sound field in the experiment is measured. After many experiments, the actual measurement value of the sound pressure is compared with the theoretical value in the focus position.The error rate is 2.9. Compared with the theoretical value, the error rate of the measured acoustic power is 4.5, which verifies the correctness of the theoretical model.The theoretical model provides an effective theoretical basis for the measurement of complex ultrasonic fields, and a new idea and method for the detection and evaluation of ultrasonic transducers.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB552

【共引文献】