Urtis: A Small 3D Imaging Sonar Sensor For Robotic Applications

State-of-the-art autonomous vehicles mainly rely on optical sensors to perceive their environment. However, the performance of these sensors worsens dramatically in environments where airborne particles are present. Sonar sensors rely on acoustic waves which are able to pass through these distortions. The data gathered from sonar could complement the distorted data of the optical sensors in these earlier mentioned environments. In this paper we will discuss the newest 3D in-air sonar sensor developed by CoSys-Lab: the micro Real Time Imaging Sonar (uRTIS). It is the smaller version of the previously developed embedded Real Time Imaging Sonar (eRTIS) and consists of a uniform rectangular array of 5 by 6 microphones compared to the pseudo-random 32 microphone array based on Poisson Disc-Sampling used with the eRTIS. In this paper we will discuss the used hardware of the uRTIS, followed by the implemented processing algorithms to form acoustic images from reflected ultrasonic data. Furthermore, we will discuss the spatial resolution that can be obtained with the presented hardware architecture using different beamforming algorithms. Finally, we will validate the real-life performance, comparing the acoustic images of the uRTIS when using Delay-And-Sum or MUltiple SIgnal Classification to solve the different directions of arrival.