毫伏级生物电信号采集装置的设计与实现

发布时间：2018-07-27 17:47

【摘要】：表面肌电信号在诊断神经肌肉功能、肌肉疲劳程度的评定及疾病的诊断等方面广泛应用。在近代,假肢的研究很盛行,而假肢的控制主要通过表面肌电信号来驱动。因此,研制出一种方便实用、性价比高的肌电信号采集电路具有重要的意义。表面肌电信号是通过电极从人体皮肤表面记录下来的神经肌肉电信号,是一种非平稳的微弱信号。本论文中介绍了表面肌电信号采集装置的设计和实现。本设计中采用AD620前置放大电路,对原始肌电信号进行初级放大。在采集电路的设计中,为了降低干扰信号的影响,设计出了高通、低通滤波电路和工频陷波器电路。首先采用Multisim仿真软件对电路进行原理性试验,然后采用分立元件搭建硬件电路,并利用Altium Designer制作出PCB电路板进行测试,实时的采集到肌电信号。在测试试验中分别通过肢体运动的方法和弱直流电刺激方法对正中神经进行电刺激实验,均采集到肌电信号。对采集到的肌电信号,文中采用时域和频域进行了研究与分析。在肢体运动中,我们对握拳肌电信号进行时频域分析,符合肌电信号的一般特征。在电刺激实验中,由时域波形可以看出,在方波电压上升沿处刺激,得到的是起始点向下的肌电脉冲波形,在方波电压下降沿时刺激,得到的是起始点向上的肌电脉冲波形,由此得出肌电信号是方波脉冲产生的电场梯度作用的结果。在频谱分析中,利用Matlab软件中的FFT对肌电信号进行频谱分析。肢体运动中,握拳信号的频率范围在0Hz-500Hz范围内较为集中,其中50 Hz-200Hz范围内幅值较高。在电刺激实验中可以得出,随着刺激电压的增加,不同频率的神经肌电信号的幅值也相应增加。在不同刺激电压时,神经电信号的主频是67.5676Hz,在0 Hz-500Hz带通滤波范围内,直流至主频之间的肌电信号幅值逐渐增加,主频到500 Hz之间的神经电信号幅值逐渐降低。
[Abstract]:Surface electromyography (EMG) is widely used in the diagnosis of neuromuscular function, muscle fatigue and disease diagnosis. In modern times, the study of prosthesis is very popular, and the control of prosthesis is mainly driven by surface electromyography (EMG) signal. Therefore, it is of great significance to develop a practical and cost-effective EMG signal acquisition circuit. Surface electromyography (EMG) is a nonstationary weak signal, which is recorded from the surface of human skin by electrodes. In this paper, the design and implementation of surface EMG signal acquisition device are introduced. In this design, AD620 preamplifier circuit is used to amplify the original EMG signal. In order to reduce the influence of interference signal, high pass, low pass filter circuit and power frequency notch filter circuit are designed in the design of acquisition circuit. First, the circuit is tested in principle with Multisim simulation software, then the hardware circuit is built with discrete components, and the PCB circuit board is made by Altium Designer for testing, and the EMG signal is collected in real time. The electromyography (EMG) signals were collected from the median nerve by the method of limb motion and weak direct current electrical stimulation. The time domain and frequency domain are used to study and analyze the collected EMG signals. In limb movement, we analyze the EMG signal in time and frequency domain, which accords with the general characteristics of EMG signal. In the experiment of electrical stimulation, it can be seen from the time domain waveform that at the rising edge of square wave voltage, the myoelectric pulse waveform is obtained at the starting point down, and when the square wave voltage drops along the edge, the myoelectric pulse waveform up to the starting point is obtained. It is concluded that the EMG signal is the result of the electric field gradient produced by the square wave pulse. In spectrum analysis, FFT in Matlab software is used to analyze the spectrum of EMG signal. In limb movement, the frequency range of grip signal is concentrated in the range of 0Hz-500Hz, and the amplitude is higher in the range of 50 Hz-200Hz. In the electrical stimulation experiment, it can be concluded that with the increase of the stimulation voltage, the amplitudes of the neuromyoelectric signals at different frequencies increase accordingly. The main frequency of the nerve signal is 67.5676Hz. in the range of 0 Hz-500Hz bandpass filtering, the amplitude of the EMG signal between DC and the main frequency increases gradually, and the amplitude of the nerve signal between the main frequency and 500Hz decreases gradually.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH789

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