A novel testing method for ultra-low-frequency vibration signal based on passive radio frequency tag sensing

Ultra-low-frequency vibration is prevalent in many critical research fields. Nevertheless, for ultra-low-frequency vibration signals below 1 Hz, there is currently a lack of a cost-effective and efficient measurement method. A new ultra-low-frequency vibration signal testing method based on the passive radio frequency tag phase is proposed using the Radio Frequency Identification (RFID) sensing method. By employing vibration detection on ultra-low-frequency vibration signals, the effectiveness of the proposed approach across different frequencies is validated while thoroughly considering factors such as measurement range, precision, distance, and occlusion effects. The results indicate that this method can accurately measure ultra-low frequency vibration signals as low as 0.01 Hz, with an average relative error of only less than 1.5% for all measurement results, and the error decreases with increasing detection frequency. For the measurement of a 1 Hz vibration signal, the average relative error is less than 1%. In addition, the measurement accuracy remains unaffected by distance or occlusion. Sensitivity and stability tests are also conducted. Continuous monitoring for 8 hours demonstrates the excellent measurement stability of the proposed method. Finally, a performance comparison has been made with laser displacement sensors commonly used in non-contact ultra-low-frequency measurement methods. The results show that the RFID sensing method can detect lower vibration frequencies and has a larger amplitude measurement range and better environmental adaptability. Overall, for ultra-low-frequency vibration, this method offers advantages such as high precision, passive non-contact operation, non-line-of-sight path monitoring, affordability, and convenience. These attributes render it suitable for extensive application in various engineering scenarios requiring ultra-low-frequency vibration testing.