Robust Acoustic Reflector Localization for Robots

The transfer function or response of an acoustic system, e.g., loudspeakers, contributes to a phase lag due to propagation delay that can hinder the performance of a time-of-arrival (TOA) estimator intended for acoustic reflector localization using echolocation. In this paper, we propose a Robust Expectation-Maximization (EM) algorithm that takes into account the response of acoustic systems to enhance the TOA estimation accuracy. To test the proposed method, a hardware proof-of-concept setup was built with two different designs. The experimental results show that the proposed method could detect an acoustic reflector up to a distance of 1.6 m with 60% accuracy under the signal-to-noise ratio (SNR) of 0 dB. Moreover, we also show that the proposed method can also be used to estimate multiple acoustic echoes that originate when a robot is placed at a corner of a room.