【作者】 齐博蕾；

【导师】 王化祥；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2007， 硕士

【摘要】 双模态电学成像系统是将电容成像(Electrical Capacitance Tomography)和电阻成像(Electrical Resistance Tomography)集成到同一敏感系统,测取敏感场区域物场分布的介电常数和电导率的过程层析成像技术。该技术具有无辐射、非侵入、响应速度快、成本低廉以及可视化测量等优点。在图像重建的过程中,信息的提取是整个技术的关键之一,信号的解调方法可以分为模拟解调和数字解调两种方式。本课题着重于双模态成像系统测量方法和数字解调方法的研究,主要研究工作和结果如下:(1)对已构建的数字化硬件系统进行了调试和改进,主要包括系统激励和测量选通电路、C/V转换电路的调试,限幅电路的设计,并对等效电路的测量方法进行了分析总结。(2)用以TMS320C6701为主要芯片的数据采集卡控制整套硬件系统并且对A/D的采样结果进行信息处理,针对数字滤波和数字解调的方法进行了研究,将双窗法FFT谱分析和参数解调等方法应用于双模态成像系统,有效提高了数字解调的速度和精度。(3)对数字化成像系统进行了误差分析,主要包括电容测量电路中放大器本身的误差及对测量结果的影响,数字解调过程中引入的误差和对测量结果的影响;通过对测量公式的分析,得到反馈电阻、反馈电容以及激励信号频率选择的标准。更多还原

【Abstract】 Dual-mode electrical tomography system including electrical capacitance tomography and electrical resistance tomography in the same system is a PT technology to obtain dielectric constant and electric conductivity of the sensing field. It has the advantages of non-radiant, non-intrusive, rapid response and low cost. Data acquisition are the key links of the technique in the image reconstruction. The method of the demodulation of the signal can be divided to analog demodulation and digital demodulation.The author focuses on the measurement methods and digital demodulation method of dual-mode tomographic system. The following achievements have been obtained:1. The digital hardware system is tested and improved on the basis of the former system including the exciting module, the measurement module and data acquisition module. The amplitude limiter circuit is designed, and the measurement methods were generalized.2. The whole hardware system is controlled by the 6701PA data acquiring card and the data is analysed. The digital demodulation methods are researched, dual-window FFT spectral analysis and parametric demodulation are introduced to the system, and improve the speed and the precision to some extent.3. The error analysis of the digital system is done, including the error introduced by the amplifier and the influence to the result, the error introduced by the digital demodulation, the influence to the result.The standard to choice the feedback resistance, the feedback capacitance and the frenquency of the exciting signals.更多还原