基于Walsh函数同时多频激励下阻抗信息提取方法研究

Research on Impedance Information Extraction Method for Multi-Frequency-One-Time Excitation based on Walsh functions

为实现基于Walsh函数的同时多频激励下生物体不同组织、器官阻抗的测量,本文对同时多频混合信号激励下复阻抗提取方法进行了初步研究。提出一种基于主谐波分量的生物电阻抗测量方法,该方法的基本思路是将被测对象的输入与输出电压分别进行FFT变换,根据欧姆定律计算出不同频点的主谐波对应的被测对象复阻抗的值。为验证FFT用于生物电阻抗测量的有效性,对简化的2R-1C细胞模型复阻抗的测量进行了仿真实验,在基频f0=6.25kHz的同时多频混合激励源f(7,t)施加于被测对象条件下,仿真测量结果的幅值最大相对误差为1.7%,相位最大绝对误差为0.9度,实验结果表明,该方法能有效地提取同一时刻,不同频率下被测对象的复阻抗信息,满足生物电阻抗测量系统的要求。

To measure the impedance o{ different tissues and organs at the same time based on Walsb {unctions excitation, this paper re- searchs a extraction method of complex impedance information under Multi--frequency one--time mixed signal excitation. A impedance im- plementation method is proposed based on primary harmonics, the main idea of the method is to measure input and output voltage about test- ed object, Fast Fourier Transform （FFT） respectively, to measure complex impedance value corresponding primary harmonics frequency points according to Ohm＇s law. In order to verify the effectiveness of the FFT for bio--impedance measurement, the experiment research for complex impedance implementation to simplified 2R--1C cell model is done, the Multi--frequency--one--time mixed signal excitation f （7, t） is applied to the object measured, its fundamental frequency f0 is 6.25 kHz, the maximum magnitude relative error is 1.7%, and the maximum phase absolute error is 0. 9 degree under the above conditions. Experimental results show that this method can effectively extract the complex impedance information of the object measured at the same time, the different frequencies, meeting the requirements of the bio-- impedance measuring system.