A High-Accuracy in-Air Reflective Rangefinder Via PMUTS Arrays Using Multi-Frequency Continuous Waves

This paper reports a high-accuracy in-air reflective rangefinder via two pieces of 492 kHz 5by5 multipled piezoelectric micromachined ultrasound transducers (pMUTs) array using multi-frequency continuous waves (MFCW). The MFCW-based rangefinder owns high accuracy intrinsically because the distance information is extracted from the phase difference, which can cancel the random noise out in numerous repeating periods. Experiment results show that the 3σ accuracy of the short distance measurement (<;100mm) is 0.0711 mm with 0.096 mm/° first-order resolution and 1.934 μm/° second-order resolution, which is 1.8208 mm for long distance measurement (100mm-300mm) with 0.481 mm/° first-order resolution and 1.954 μm/° second-order resolution.