Movement tracking using asymmetric impedance meta-surface based on Helmholtz resonator

Acoustic sensors are one of the most commonly used sensors for detecting obstacles in mobile robots and vehicles by providing distance information of the obstacles in their path. However, although a single sensor can determine an object's distance, two or more sensors must be used to detect the movement of an object. Here, we propose a method to determine the distance and direction of an object traveling to a single sensor using an asymmetrically formed acoustic field. The acoustic field is formed by impedance-varying acoustic meta-surface using an asymmetric Helmholtz resonator array. We present multi-physics simulations using COMSOL and experimental results which show the movement of an acoustic source using a single microphone. Also, we present, explicitly, the effective material parameter variation made by the meta-surface with varying degrees of internal neck lengths.