地铁列车振动环境响应的无线传感器网络快速评定

Fast assessment of ambient responses induced by subway train vibration using wireless sensor networks

地铁列车振动环境微弱响应的无线传感器网络测试需要mg量级的加速度测试精度,常规板载MEMS加速度传感器通常难以满足。采用低噪声运算放大器OPA4344与模拟/数字转换器QF4A512,将MEMS加速度传感器SD1221L-002量程限定在±0.2 g,同时采用进行信号转换与调理,达到了0.043 mg的加速度测试分辨率,满足了地铁列车环境微振测试要求。基于英特尔Imote2无线传感器网络硬件平台与嵌入式软件平台ISHMP Services Toolsuite,实现了地铁列车振动环境加速度测试专用无线传感器网络系统。基于Tiny OS开源操作系统,采用组件式结构程序语言nes C编写了嵌入式应用组件Vibration Level Calculation,实现了环境振级的嵌入式计算。应用该系统,对一地铁紧邻地下空间内地铁列车环境振动响应进行了实测。通过传感节点采集环境加速度信号,在传感节点Imote2主板内嵌入式计算振级,通过无线传输数据,在终端直接显示出测试环境振级分布。通过回溯存储于传感节点内三分之一倍频程中心频率上的振级数据,获得了各测点1/3倍频程。该系统实现了地铁列车振动环境响应的快速评定。

The measurement of weak ambient acceleration responses, induced by subway train vibrations, needs an accuracy of mg scale, which could not be easily satisfied using ordinary on-board MEMS accelerometers. In the paper, by using the low-noise OP-Amp OPA4344 and ADC Q4FA512, the measurement range of the MEMS accelerometer SD1221L-002 was limited in ±0.2 g, so as to accomplish an acceleration resolution of 0.043 mg to satisfy the testing requirement of weak ambient vibrations. A specific wireless sensor network system was developed for the testing of subway train induced ambient accelerations. The system was based on Intel Imote2 wireless sensor network platform, combined with the embedded software platform ISHMP Services Toolsuite. Based on the open-source operation system TinyOS, the component structural programming language nesC was used to program the embedded application component VibrationLevelCalculation, so as to embeddedly compute the ambient vibration level. The system was used to measure the ambient vibration responses induced by subway train vibrations of an underground space adjoining the subway station. The ambient acceleration signals were acquired at the sensor nodes the vibration levels were embeddedly computed in the Imote2 main board of the sensor board, and the distribution of the ambient vibration level was directly displayed on the terminal. In addition, the one-third octave bands spectra at measuring points were obtained by retrieving the vibration level data at the center frequencies stored inside the sensor nodes. The developed system implements the fast assessment of the ambient responses induced by subway train vibrations. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.