Ultrasonic rangefinder with resolution in hundredths of the probing signal's wavelength for the mobile rescue robot

Stanislaw Goll, Julia Maximova

Abstract


The main goal of this research is to increase the measurement resolution of ultrasonic rangefinders to meet the needs of vital signs noncontact registration based on chest movements. The two-phase method is proposed to make distance estimates by sending probe pulse trains, calculating the phase spectrum of the echo signal’s envelope, and tracking its relevant components. During the first phase, rough Time-of-Flight (ToF)-based estimates are made. During the second phase, this estimate is corrected based on the phase spectrum of the echo signal’s envelope, the phase ambiguity is removed, and the relevant components are determined. The final estimate of the human chest displacement is calculated based on these relevant components. The output data rate is the same as for the ToF-based measurements, but the measurement resolution is increased to one hundredth of the ultrasonic wavelength. The experiment results are provided for the both model and the real human chest displacements caused by the respiration and heartbeat processes.

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DOI: http://dx.doi.org/10.21014/acta_imeko.v8i4.686