Hello Developers,
We are currently developing a product for industrial machines condition monitoring and predictive maintenance application. For evaluation purpose we have bought "STEVAL-STWINKT1B" for the same. We are using the "en.stsw-stwincell" cellular example for publishing stwin's data to the aws cloud. In this example for vibration analysis, on board IIS3DWB sensor is used with default sensor parameters (i.e stated below) and the Time Domain Analysis output (i.e Acc RMS, Acc Peak and Speed Rms) in all 3-axis is published on the AWS cloud after the Time Domain and Frequency Domain analysis has finished i.e after TACQ (5 seconds). And for reference measurements we are using SPM Portable Vibration meter (VIB-15) based on analog sensor, generally used in industries for measurement of true acceleration and velocity values in 1-axis of machine for condition monitioring.
Parameters used in Cellular Example:
IIS3DWB Configuration
Acc ODR: IIS3DWB_XL_ODR_26k7Hz
FIFO BDR: IIS3DWB_XL_BATCHED_AT_26k7Hz
Effective ODR: 26.9KHz
FS: ACCELERO_FS_16
HW_Filter: IIS3DWB_HP_ODR_DIV_800
FFT Parameters:
FFT Size: 1024
FFT OVL: 50
TAU : 50
Window: Hanning
TD Analysis: Speed & Accelero
TACQ: 5000 (5 seconds)
Issue:
Now we have a Compressor/Chiller/Motor equipment in Industry on which we are measuring the Acc Rms and its velocity during its normal working condition. Now as IIS3DWB sensor is digital sensor it's output is measured in all direction, but we are only taking into consideration the effective Y axis of digital sensor as it aligns with the SPM vibra meter. Now we took readings of Acc Peak, Acc Rms, Speed Rms using both STWIN kit and SPM vibra meter. But the measured reading from the STWIN are drastically different from the vibra meter (i.e almost double at higher vibrations). Also we converted the value of Acc rms into G, as the measured value of acceleration is in G for vibrameter and velocity rms have same unit of mm/s in both devices.
So i would like to know what could be the issue here as measured values are taken in similar conditions and both devices were well mounted ? Shouldn't STWIN TDM data should match or come nearby the readings of SPM vibra meter ? Or we are doing wrong thing by comparing the analog sensor output with digital sensor output although the end appplication is same.
Reference Links:
ST Win board:
https://www.st.com/en/evaluation-tools/steval-stwinkt1b.html
SPM VibraMeter:
https://www.spminstrument.com/products-and-services/portable-instruments/vibchecker/
https://3.imimg.com/data3/JU/PS/MY-1959092/vibration-meter.pdf
Setup Images for Reference:
