Elevation Angle Estimations of Wide-Beam Acoustic Sonar Measurements for Autonomous Underwater Karst Exploration

Yohan Breux (1) , Lionel Lapierre (1)

1 EXPLORE - Robotique mobile pour l'exploration de l'environnement

This paper proposes a solution for merging the measurements from two perpendicular profiling sonars with different beam-widths, in the context of underwater karst (cave) exploration and mapping. This work is a key step towards the development of a full 6D pose SLAM framework adapted to karst aquifer, where potential water turbidity disqualifies vision-based methods, hence relying on acoustic sonar measurements. Those environments have complex geometries which require 3D sensing. Wide-beam sonars are mandatory to cover previously seen surfaces but do not provide 3D measurements as the elevation angles are unknown. The approach proposed in this paper leverages the narrow-beam sonar measurements to estimate local karst surface with Gaussian process regression. The estimated surface is then further exploited to infer scaled-beta distributions of elevation angles from a wide-beam sonar. The pertinence of the method was validated through experiments on simulated environments. As a result, this approach allows one to benefit from the high coverage provided by wide-beam sonars without the drawback of loosing 3D information.

Mots clés: Karst; Underwater; Sonar; SLAM; AUV; 3D

Domaines: Acoustique [physics.class-ph]; Traitement du signal et de l'image [eess.SP]; Robotique [cs.RO]; Ingénierie de l'environnement

Yohan Breux, Lionel Lapierre. Elevation Angle Estimations of Wide-Beam Acoustic Sonar Measurements for Autonomous Underwater Karst Exploration. Sensors, 2020, 20 (14), pp.4028. ⟨10.3390/s20144028⟩. ⟨hal-02935446⟩