3D localization by a biomimetic sonar system in a fire-fighting application

In this study we investigate the effects of medium disturbances on the usability of a biomimetic sonar system in a target localization application. In particular, we concentrate on a fire-fighting application giving rise to specific types of medium disturbances. We determine experimentally the effects of these medium disturbances: undisturbed air (reference), the presence of small water droplets, large convective air-currents and flames, on the received echo spectra. As the echo spectra are used to estimate the target location, these different conditions by disturbing to varying extents sound propagation through the medium will have an effect on the sonar system's localization performance. Using an information theoretic model of the spectrum based localization mechanism we characterize the loss in localization accuracy due to the different medium disturbances. We conclude that an echolocation system based on the sonar system of the bat Phyllostomus discolor allows for robust localization even in highly disturbed media. However, while the need for replacing the emission pattern of the bat by that of a standard transducer in the biomimetic sonar system makes little difference in the ‘reference’ and ‘water spray’ conditions it limits echolocation performance in the ‘air-currents’ condition and makes the use of the proposed system very difficult in the ‘flames’ condition.