OpenSWAP, an Open Architecture, Low Cost Class of Autonomous Surface Vehicles for Geophysical Surveys in the Shallow Water Environment

Abstract

OpenSWAP is a class of innovative open architecture, low cost autonomous vehicles for geological/geophysical studies of shallow water environments. Although they can host different types of sensors, these vehicles were specifically designed for geophysical surveys, i.e., for the acquisition of bathymetric and stratigraphic data through single- and multibeam echosounders, side-scan sonars, and seismic-reflection systems. The main characteristic of the OpenSWAP vehicles is their ability of following pre-defined routes with high accuracy under acceptable weather and sea conditions. This would open the door to 4D (repeated) surveys, which constitute a powerful tool to analyze morphological and stratigraphic changes of the sediment/water interface and of the shallow substratum eventually caused by sediment dynamics (erosion vs. deposition), slumps and gravitative failures, earthquakes (slip along seismogenic faults and secondary effects of shaking), tsunamis, etc. The low cost and the open hardware/software architectures of these systems, which can be modified by the end users, lead for planning and execution of cooperative and adaptive surveys with different instruments not yet implemented or tested. Together with a technical description of the vehicles, we provide different case studies where they were successfully employed, carried out in environments not, or very difficultly accessed through conventional systems.

Xiroi II, an Evolved ASV Platform for Marine Multirobot Operations

“…In terms of platform design, depending the applications and the navigation environment, the developer should pay special care on the stability, the maneuverability, the speed and the safety of the ASV. Platform designs can mainly be divided in monohull [ 16 , 17 , 18 ] and multihull [ 8 , 19 , 20 , 21 , 22 ] solutions. Looking on current catamaran hull designs, the AERO4RIVER ASV [ 23 ] presents a new propulsion system based on aerial thrusters that allows allows navigation in very shallow waters.…”

Shallow Water Bathymetry Survey using an Autonomous Surface Vehicle

“…Catamaran structures have higher stability due to the wider beams, lesser power requirements due to smaller hydrodynamic resistance, and shallower draught, which helps in shallower areas. [8] Since the acoustic and ultrasonic signal generated by the sonar transducer should be perfectly coupled with the water and the sensor should also be shielded from the effect of turbulence, the design of the components, propellants, and sensor placements was planned accordingly as shown in Figures 1 and 2.…”

Creating an Autonomous Hovercraft for Bathymetric Surveying in Extremely Shallow Water (<1 m)

“…USVs can decrease their minimum water depth by decreasing their size, and therefore maximum weight allotment, such as in a study by Giordano et al [16] using a small catamaran drone (1.35 × 0.85 m), which can be operated in depths of 0-20 m, but cannot run on land as well as water. Similarly, the catamaran USVs developed by Stanghellini et al [17] and Martorell-Torres et al [18] use two small underwater propellers which can work in very shallow environments yet cannot be directly deployed from land. Some USVs have adapted their propulsion mechanisms for shallow water by using waterjet or waterjet-inspired propulsion to be able to maneuver in shallow water without risking damage [19].…”

“…Some USVs have adapted their propulsion mechanisms for shallow water by using waterjet or waterjet-inspired propulsion to be able to maneuver in shallow water without risking damage [19]. Even if these propulsion mechanisms do not greatly affect the vehicle's ability to maneuver in the shallow environment, many surveying instruments are sensitive to underwater noise which could be generated by bubbles and turbulence caused by propellers or water jets [17].…”