机械振动无线传感器网络节点高精度数据采集方法

摘要

为满足通用机械振动监测中高采样率、采集精度的需求，提出一种基于 IEPE 加速度传感器的无线传感器网络节点高精度数据采集方法。采用双核心处理器构架，降低网络维护与采集控制的耦合性，独立高精度时钟控制采集时序，提高数据采集频率精度。设计低噪声 DC-DC 电源转换方案，在充分考虑转换效率的前提下抑制电源噪声为30μVRMS；设计能自抑制电源噪声的恒流源激励，减小 IEPE 加速度传感器的信号噪声；设计通带平稳的三阶低通滤波器，有效避免频率混叠，提高数据采集幅值精度。实验结果表明：节点采集信号噪声仅40．7μVRMS ，滤波通带范围内平均幅值误差仅0．37％；与有线采集系统 NI9234数据采集对比分析，频率误差低于最小频率分辨率，幅值误差最大仅2．99％，验证了该无线传感器网络节点高精度数据采集方法的有效性。%In order to meet the requirements of high sampling rate and precision in general mechanical vibration monitoring,a high precision data acquisition method of wireless sensor networks(WSNs)node was proposed based on IEPE accelerometers.A dual-core-processor architecture was adopted to reduce the coupling of network maintenance and acquisition control.An independent high precision clock was used to control the acquisition timing,which improved data collection frequency accuracy.A scheme of low noise DC-DC power conversion was designed,which took into full consideration of the conversion efficiency and thus controlled the power supply noise rejection within 30μVRMS .The high precise constant current source with power supply noise self-rejection was designed,which reduced the signal noise of IEPE accelerometers.Furthermore,the steady passband ripple three-order low pass filter was designed for avoiding the frequency aliasing effectively and improving the data acquisition amplitude accuracy.Experimental results indicate that the signal noise is only 40.7μVRMS and the average amplitude error within passband is only 0.37%.In comparison with the data collection of wired system NI9234,the frequency error of WSNs is within the minimum frequency resolution,and the maximum amplitude error is only 2.99%.Results verify the validity of the high precision data acquisition method of mechanical vibration wireless sensor networks node.