Multi-robot global sonar survey in the presence of strong currents

Abstract

This paper considers conducting underwater surveys using multiple sonar-equipped Autonomous Surface Vehicles (ASVs). Given a workspace, every ASV simultaneously searches for a mine towing a Side Scan Sonar (SSS) which can provide high-resolution image of underwater environments. Under strong currents, a survey may result in blurry sonar image, which is not desirable for detecting mines. In the case where the heading of the ASV is opposite to the direction of currents, we can obtain vivid sonar images suitable for detecting mines. This paper thus introduces global path planning of multiple ASVs satisfying the following three goals: 1. there is no hole in coverage after the search is done. 2. whenever an ASV performs sonar survey inside the workspace, the heading of the ASV is opposite to the direction of currents. 3. the workload of every ASV is balanced for time-efficient search. We verified the effectiveness of our multi-ASV path planning methods using MATLAB simulations.