Lightweight Autonomous Underwater Vehicles Research Articles

Design and Implementation of Lightweight AUV With Multisensor Aided for Underwater Intervention Tasks

Autonomous underwater vehicles (AUVs) are commonly used to conduct complex underwater tasks, such as marine infrastructure overhaul and maintenance, environmental monitoring, oceanographic mapping, and organism capture. These tasks require the ability of an AUV to perform autonomous navigation, especially when communication is limited in the underwater environment. This brief developed a new type of lightweight intervention AUV for autonomous navigation using data from multiple inertial sensors, where multi-sensor error state Kalman filter schemes are preferable to standard Kalman Filters in terms of the AUV’s motion estimates. Concerning target recognition, a color restoration method is provided for degraded underwater images and a You Only Look Once strategy is combined with topological analysis for object detection. In addition, the proposed design is robust in terms of its software components and mechanical structure, which provides a feasible platform for AUV’s secondary development. Experiments of surveying and object manipulation conducted in underwater environments demonstrate the functionality of the entire system and its potential applications in the fields of science and industry.

A novel adaptive backstepping sliding mode control for a lightweight autonomous underwater vehicle with input saturation

Accurate depth and heading control play an essential role for autonomous underwater vehicles (AUVs) in near-seabed exploration and ocean surveys. This paper proposed a novel adaptive backstepping sliding mode control (ABSMC) algorithm for a lightweight autonomous underwater helicopter (AUH) subject to highly coupled nonlinearities, unknown system parameters, disturbances uncertainties, and input saturation. This algorithm adopted a conditional adaptation algorithm to govern adaptation so that gains only adapt when necessary to improve stability. Different reaching laws were selected for heading and depth control to reduce system chattering. For thruster saturation, we proposed an anti-windup compensator for auxiliary dynamic compensation based on system states; it can make the controller output change smoothly in the event of input saturation to better meet the response characteristics of the actual physical actuator. The mathematical proofs of the proposed algorithms are presented. Simulation results are presented to illustrate the effectiveness of the proposed control method. Moreover, extensive experimental results show that the proposed algorithm has better control performance than PID and sliding mode controllers and demonstrate its adaptive capability to system state changes.

Underwater Acoustic Positioning Based on MEMS Microphone for a Lightweight Autonomous Underwater Vehicle "Kyubic"

Underwater Acoustic Positioning Based on MEMS Microphone for a Lightweight Autonomous Underwater Vehicle "Kyubic"

Underwater Robotics Competitions: The European Robotics League Emergency Robots Experience With FeelHippo AUV.

Underwater robots are nowadays employed for many different applications; during the last decades, a wide variety of robotic vehicles have been developed by both companies and research institutes, different in shape, size, navigation system, and payload. While the market needs to constitute the real benchmark for commercial vehicles, novel approaches developed during research projects represent the standard for academia and research bodies. An interesting opportunity for the performance comparison of autonomous vehicles lies in robotics competitions, which serve as an useful testbed for state-of-the-art underwater technologies and a chance for the constructive evaluation of strengths and weaknesses of the participating platforms. In this framework, over the last few years, the Department of Industrial Engineering of the University of Florence participated in multiple robotics competitions, employing different vehicles. In particular, in September 2017 the team from the University of Florence took part in the European Robotics League Emergency Robots competition held in Piombino (Italy) using FeelHippo AUV, a compact and lightweight Autonomous Underwater Vehicle (AUV). Despite its size, FeelHippo AUV possesses a complete navigation system, able to offer good navigation accuracy, and diverse payload acquisition and analysis capabilities. This paper reports the main field results obtained by the team during the competition, with the aim of showing how it is possible to achieve satisfying performance (in terms of both navigation precision and payload data acquisition and processing) even with small-size vehicles such as FeelHippo AUV.

Low-Altitude and High-Speed Terrain Tracking Method for Lightweight AUVs

This paper proposes a new method for cruising-type autonomous underwater vehicles (AUVs) to track rough seafloors at low altitudes while also maintaining a high surge velocity. Low altitudes are required for visual observation of the seafloor. The operation of AUVs at low altitudes and high surge velocities permits rapid seafloor imaging over a wide area. This method works without high-grade sensors, such as inertial navigation systems (INS), Doppler velocity logs (DVL), or multi-beam sonars, and it can be implemented in lightweight AUVs. The seafloor position is estimated based on a reflection intensity map defined on a vertical plane, using measurements from scanning sonar and basic sensors of depth, attitude, and surge velocity. Then, based on the potential method, a reference pitch angle is generated that allows the AUV to follow the seafloor at a constant altitude. This method was implemented in the AUV HATTORI, and a series of sea experiments were carried out to evaluate its performance. HATTORI (Highly Agile Terrain Tracker for Ocean Research and Investigation) is a lightweight and low-cost testbed designed for rapid and efficient imaging of rugged seafloors, such as those containing coral reefs. The vehicle succeeded in following a rocky terrain at an altitude of approximately 2 m with a surge velocity of approximately 0.8 m/s. This paper also presents the results of sea trials conducted at Ishigaki Island in 2017, where the vehicle succeeded in surveying the irregular, coral-covered seafloor.

Evaluating the impact of sewage discharges on the marine environment with a lightweight AUV

Environmental studies that use small Autonomous Underwater Vehicles (AUVs) can survey wider and deeper areas, compared to traditional methods, at a reasonable cost. Thanks to the precise vehicle navigation systems, the data collected can be accurately geolocalized. Besides, lightweight vehicles can be deployed from the shore or from small boats and programmed by means of user-friendly graphical interfaces, thus reducing and simplifying the need of human resources and infrastructures. Based on such a technology, this paper presents a framework to assess the environmental impact of a marine sewage outfall set in the Bay of Palma (Mallorca, Spain). We report the results of the analysis of the images recorded in the course of six missions conducted with an AUV. The plan was designed after a microbiological analysis detected the presence of cyanobacteria in a sample of sand and water collected by scuba divers close to the sewer pipe mouth.

Design and Analysis of a Three-Phase Wireless Charging System for Lightweight Autonomous Underwater Vehicles

Lightweight autonomous underwater vehicles (AUVs), powered by rechargeable batteries, are widely deployed in inshore surveying, environmental monitoring, and mine countermeasures. While providing valuable information in locations humans have difficulty accessing, limited battery capacity of such systems prevents extended mission times. In order to extend mission times, this paper proposes a three-phase wireless charging system that could be used in a field-deployable charging station capable of rapid, efficient, and convenient AUV recharging. Wireless charging should not, however, affect instrumentation located inside the AUV. Thus, a three-dimensional finite element analysis tool is employed to study the characteristics of magnetic fields inside the AUV during three-phase charging. Simulation results reveal that the magnetic field generated by the proposed three-phase coil structure is concentrated away from the center of the AUV, where instrumentation would nominally be located. Detailed circuit analysis and compensation method to achieve resonance on both transmitter's and receiver's sides are also given. To validate the proposed concept, a three-phase wireless charging system is developed. Experimental results demonstrate that the system is able to transfer 1.0 kW with a dc–dc efficiency of 92.41% at 465 kHz.

A Rotation-Resilient Wireless Charging System for Lightweight Autonomous Underwater Vehicles

This paper presents a rotation-resilient wireless charging system with a reversely wound receiver that supports efficient charging for lightweight autonomous underwater vehicles. By employing a two-part reversely wound receiver coil structure, the total mutual inductance of the proposed coil structure remains relatively constant when rotational misalignment between the transmitter and receiver coils occurs, thereby ensuring wireless charging power is nearly continuous during rotational misalignment. Finite element analysis was performed with ANSYS Maxwell to verify the proposed coil structure. Double-sided LCC compensation topology was applied and circuit analysis was conducted via a mesh current method. A prototype of the rotation-resilient wireless charging system with the proposed coil structure was built and tested. Experimental results are well-matched to simulations, demonstrating that the system can deliver 745 Watts at a dc-dc efficiency of 86.19% when the system is fully aligned, and efficient under worst-case rotational misalignment.

Development and Design of a Compact Autonomous Underwater Vehicle: Zeno AUV

The paper describes the electromechanical design of a compact, light-weight Autonomous Underwater Vehicle (AUV) for archaeological applications; the vehicle is named Zeno (Zeno Environment Nautical Operator), protector of freshwater and flood victims, and was developed in the framework of the European project ARCHEOSUb; the AUV specifications, its navigation devices and payload are given. The main characteristics of the vehicle are described with particular attention to its system architecture, propulsion system and structural design. Zeno AUV is currently under assembly and its first tests are scheduled for Summer 2018.

Towards Visual Detection, Mapping and Quantification of Posidonia Oceanica using a Lightweight AUV

Abstract: Posidonia Oceanica (P.O.) is a Mediterranean endemic seagrass strongly related to the health of the coastal ecosystems. Monitoring the presence and state of P.O. is essential not only for safeguarding the shallow-water life diversity, but also as an indicator of the water quality. Nowadays, the control of P.O. is done by divers in successive missions of a duration limited by the capacity of the scuba tanks. This paper proposes the application of robotic and computer vision technologies to upgrade these current methods, namely: 1) employing a lightweight Autonomous Underwater Vehicle (AUV) equipped with cameras to survey and image marine areas, 2) the automatic discrimination of P.O. from the rest of the seafloor, using several techniques based on image texture analysis and machine learning , and, 3) the fast computation of 2D maps (photo-mosaics) of the surveyed areas from all the images included in the grabbed video sequences; these mosaics are extremely useful to measure the real extension of the meadows and some of the descriptors needed for a biological analysis. Experiments conducted with an AUV in several marine areas of Mallorca reveal promising results in the discrimination of different patterns of P.O. and in the construction of highly realistic photo-mosaics of the surveyed areas.

2P1-H11 沿岸調査を目的とした自律型水中ロボットの設計 : 第1報:3D-CADを用いた設計と応力解析(水中ロボット・メカトロニクス(2))

Recently, Autonomous Underwater Vehicle (AUV) has been developed by many organizations. However, These AUVs are developed for Deep Ocean. Therefore, these AUVs need support ship and many people. In this research, we aim to develop a small and light-weight AUV for coastal survey. In costal survey, the robot doesn't need the big scale and a lot of equipment. Therefore, we designed a small and light-weight robot. In this paper, we explain how to develop the AUV. Also, we report the result of stress analysis of parts which developed by bear the stress.

Lightweight Autonomous Underwater Vehicles (AUVs) performing coastal survey operations in REP 10A

Lightweight Autonomous Underwater Vehicles (AUVs) were developed for Naval Special Warfare (NSW) Group 4 search and survey missions from a commercial AUV baseline (Iver 2) through integration of commercial off-the-shelf (COTS) hardware components, and through software development for enhanced on-board Command and Control functions. The development period was 1 year under a project sponsored by the Office of Naval Research TechSolutions Program Office. Hardware integration was completed by the commercial AUV vendor, OceanServer Technology, Inc., and software development was conducted by the Naval Undersea Warfare Center, Naval Oceanographic Office, and U MASS Dartmouth, with support from hardware and software application providers (YSI, Inc., Imagenex Technology Corp., and CARIS). At the conclusion of the integration and development period, an at-sea performance evaluation was scheduled for the Lightweight NSW AUVs with NSWG-4 personnel. The venue for this evaluation was the NATO exercise Recognized Environmental Picture 10A (REP 10A), hosted by Marinha Portuguesa, and coordinated by the Faculdade de Engenharia–Universidade do Porto. REP 10A offered an opportunity to evaluate the performance of the new AUVs and to explore the Concept of Operations (CONOPS) for employing them in military survey operations in shallow coastal waters. Shore- and ship-launched scenarios with launch/recovery by a single operator in a one-to-many coordinated survey, on-scene data product generation and visualization, data push to Reach Back Cells for product integration and enhancement, and survey optimization to streamline survey effort and timelines were included in the CONOPS review. Opportunities to explore employment of hybrid AUV fleets in Combined Force scenarios were also utilized. The Naval Undersea Warfare Center, Marinha Portuguesa, the Faculdade de Engenharia–Universidade do Porto, and OceanServer Technology, Inc., were the primary participants bringing in-water resources to REP 10A. Technical support and products were provided by the Naval Research Laboratory–Stennis Space Center, Naval Oceanographic Office, NATO Undersea Research Centre, University of Massachusetts–Dartmouth, and YSI, Inc. REP 10A proved to be a very effective exercise in meeting each of the critical goals. Results of the performance evaluation guided final development and Independent Verification and Validation (IV&V) for the Lightweight NSW AUV, leading to on-time, successful Factory Acceptance Testing and delivery of the three contracted vehicles to NSWG-4 in September, 2010.

Fòlaga: A low-cost autonomous underwater vehicle combining glider and AUV capabilities

The paper describes the current developments of a class of low-cost, light-weight autonomous underwater vehicles for coastal oceanographic applications; the vehicle class is named Fòlaga, the Italian name of an aquatic bird that swims on the water surface and dives to catch fish. The main design characteristics of the most recent vehicle of the class, the Fòlaga III, are reviewed. Navigation and control system design are discussed, with particular attention to the diving phase, which is accomplished as in oceanographic gliders by varying the vehicle buoyancy and attitude. Experimental results show that the PID robust controllers implemented are effective in the diving control phase. Finally, a distributed cooperation algorithm to be applied by a team of Fòlaga-like vehicles in adaptive oceanographic sampling applications is described. The algorithm optimizes area coverage while taking into account the accuracy in the reconstruction of the oceanographic field and inter-vehicle communication through a range constraint. The resulting dynamic programming algorithm can be implemented in a distributed fashion among the team components.