Showing papers on "Intervention AUV published in 2002"

Autonomous Buoyancy-Driven Underwater Gliders

Abstract: A class of small (50 kg, 2 m length), reusable autonomous underwater vehicles capable of operating at speeds cm/s with ranges several thousand kilometers and durations of months has been developed and tested. The vehicles, autonomous profiling floats with wings, execute sawtooth patterns between the surface, where they are located and com to shore, and depths of O(1000 m). These vehicles are commanded remotely and report results to shore in near real tim ent approaches to the various design issues are embodied in the vehicles Spray, Seaglider and Slocum models desc including batteryand thermal-powered propulsion, different depth and speed capabilities, diverse hydrodynamic appro reducing drag and gliding control, various communication schemes, and a range of sensors. These approaches are des examples of completed scientific missions are given. l., e st els. h ic es rs s, ing ult g, em cg on the ive is cles an be an eing ean urand the lidin

A vision system for an underwater cable tracker

Abstract: Nowadays, the surveillance and inspection of underwater installations, such as power and telecommunication cables and pipelines, is carried out by operators that, being on the surface, drive a remotely operated vehicle (ROV) with cameras mounted over it. This is a tedious and high time-consuming task, easily prone to errors mainly because of loss of attention or fatigue of the human operator. Besides, the complexity of the task is increased by the lack of quality of typical seabed images, which are mainly characterised by blurring, non-uniform illumination, lack of contrast and instability in the vehicle motion. In this study, the development of a vision system guiding an autonomous underwater vehicle (AUV) able to detect and track automatically an underwater power cable laid on the seabed is the main concern. The vision system that is proposed tracks the cable with an average success rate above 90%. The system has been tested using sequences coming from a video tape obtained in several tracking sessions of various real cables with a ROV driven from the surface. These cables were installed several years ago, so that the images do not present highly contrasted cables over a salady seabed; on the contrary, these cables are partially covered in algae or sand, and are surrounded by other algae and rocks, thus making the sequences highly realistic.

UUV teams, control from a biological perspective

Abstract: Remote Operated Vehicles (ROVs) are used extensively for salvage operations, ocean floor surveying and numerous inspection activities that support a wide range of underwater commercial activities. In deep water (greater than 1000 ft) an ROV is the platform of choice because of the depth and endurance limitations for human divers. The key disadvantage to an ROV is the requirement for the long tether. The tether greatly inhibits the speed of the ROV, requires a ship with deck gear capable of handling this cable, and significantly restricts ship movement while deployed. Un-tethered Unmanned Underwater Vehicles (UUVs) have entered the commercial market and have demonstrated the ability to perform deep-water surveys faster and cheaper than towed vessels. With further technological advances, UUVs have the potential for supplementing and even replacing ROVs for many deep-water operations because of the cost and problems associated with the tether. One promising scenario for the near future is to use an ROV or surface ship to control multiple UUVs in a local work area. Typically in this scenario the UUVs are used to extend the sensor footprint of the ROV or surface ship. Another area of interest is the UUV team concept. A stereotypical UUV team would be a heterogeneous mix of several low-cost specific purpose vehicles, guided and supported by one or two higher cost control vessels. Because of the severe restrictions that the sub-sea environment places on communication and positioning, precision underwater navigation is difficult. Currently most precision underwater navigation relies on some sort of infrastructure such as surface ships or underwater beacons placed in known positions. Using these assets as reference-points sub-sea navigation is carried out. Some situations require that the environmental and/or commercial attributes of an area be assessed before an infrastructure exists. In order to do this the UUV team must be able to navigate to an area, carry out its task and return without any pre-existing infrastructure or step by step guidance. Given basic assumptions about the type and frequency of sensor input we present a biologically inspired, decentralized methodology for safely and efficiently moving a loose formation of UUV's to and from the task area with the goal of minimizing outside guidance.

Design concept and experimental results of the autonomous underwater vehicle AQUA EXPLORER 2 for the inspection of underwater cables

Abstract: AQUA EXPLORER 2 (AE2) is the first and only autonomous underwater vehicle in the world which can autonomously track underwater cables and measure their burial depth. Its weight in air is about 260 kg, and its dimensions are 3 m in length, 1.3 m in width and 0.9 m in height. It can swim freely up to 500 m in depth for 24 h continuously. Although the vehicle can communicate with a mother vessel with an acoustic link, only high-level commands are sent to the vehicle and most of the control is done by a built-in computer. When tracking underwater cables, low-frequency current is supplied to the underwater cables. The vehicle can locate and track cables by detecting the magnetic field generated by the current. Since it was first launched in 1997, AE2 has carried out three sea trials and five cable-inspection missions. The total length of inspected cable exceeds 400 km. In 1999, in a real inspection of an underwater telecommunication cable crossing the Taiwan Straight, it was proved that AE2 was robust against ...

The effect of forward vehicle velocity on through-body AUV tunnel thruster performance

Abstract: New applications of streamlined Autonomous Underwater Vehicles require an AUV capable of completing missions with both high-speed straight-line runs and slow maneuvers or station keeping tasks. At low, or zero, forward speeds, the AUV's control surfaces become ineffective. To improve an AUV's low speed maneuverability, while maintaining a low drag profile, through-body tunnel thrusters have become a popular addition to modem AUV systems. The effect of forward vehicle motion and sideslip on these types of thrusters is not well understood. In order to characterize these effects and to adapt existing tunnel thruster models to include them, an experimental system was constructed. This system includes a transverse tunnel thruster mounted in a streamlined AUV. A 6-axis load cell mounted internally was used to measure the thrust directly. The AUV was mounted in Memorial University of Newfoundland's tow tank, and several tests were run to characterize the effect of vehicle motion on the transient and steady state thruster performance. Finally, a thruster model was modified to include these effects.

Results from mechanical docking tests of a Morpheus class AUV with a dock designed for an OEX class AUV

Abstract: This paper reports on a series of experiments done to test the feasibility of docking a Morpheus class autonomous underwater vehicle (AUV) on a dock originally designed for the much larger OEX class AUV. These tests were designed to observe the reaction of the vehicle upon impact with the dock and determine the success rate of the mechanical system. The tests were done at sea with the dock resting on the sea floor using divers to start and stop the vehicle for each run. Diver observations and video, as well as logged vehicle sensor data were then used to draw conclusions on the viability of the docking system.

Avoidance of underwater cliffs for autonomous underwater vehicles

Abstract: This paper introduces a method aiming to allow underactuated autonomous underwater vehicles navigating in an unknown environment to avoid underwater cliffs. Three electro-acoustic transducers situated in the front part of the vehicle provide bathymetric data. In this article we detail the method adapted to an irregular seabed, i.e., with substantial changes in depth like underwater cliffs. The obtained trajectories respect the dynamic constraints of the vehicle. We also explain how to choose the orientation angle of transducers in order to optimize the quality of seabed following. Our method was validated with the hydrodynamic simulator of the "Taipan" vehicle, which is our laboratory's autonomous underwater vehicle prototype.

Design of an Inspection Class Autonomous Underwater Vehicle

Abstract: Autonomous Underwater Vehicles (AUVs) have become ever more common in ocean science, military, and industrial applications. In particular, AUVs are becoming a significant option for undersea search and survey. Bottom following, tight turning radius, stability, and elimination of tow cables make AUVs appealing in this role. Recent commercial success has proven that AUVs can be competitive survey platforms. While AUVs that perform surveys have become more common and capable, there are few designed for close inspection tasks. These missions call for an AUV that can move slowly, on the order of 10-15 cm/sec, maneuver equally well in all three dimensions, and maintain a very stable orientation over the seafloor, usually for imaging and production of photo mosaics. The range and endurance requirements of an inspection class AUV are expected to be small compared to an AUV designed to survey large areas. The MIT AUV Lab is actively investigating the design of a new type of underwater vehicle, known as an Inspection Class AUV, for missions such as marine archaeology and fisheries habitat studies. Two new designs have been created, both of which are radical evolutions of existing Odyssey class vehicles. One design takes the proven subcomponents of the Odyssey II, namely the pressure spheres, sensors and actuators, and transfers them to an entirely new mechanical framework. The other design capitalizes on the modular nature of the Odyssey III vehicles and adds new modules that allow an Odyssey III to perform inspection tasks. This paper discusses the details of these new designs, their anticipated performance specifications and lessons learned from deployment of conventional Odyssey vehicles for inspections tasks.

Development of autonomous underwater vehicles in Japan

Abstract: In the hope of expanding underwater observation and research, the Institute of Industrial Science (IIS) at the University of Tokyo started extensive R&D on autonomous underwater vehicle (AUV) in 1984. IIS has constructed nine vehicles, including three ocean-going vehicles, one lake survey vehicle and various testbed vehicles. The R-One Robot is equipped with a closed-cycle diesel engine system and it successfully completed a 12-h operation of long-range autonomous diving in the Pacific Ocean in 1998. Utilizing the testbed robots, many intelligent systems, especially those for underwater vision systems, have been developed. The success of these AUVs at the IIS has led to the establishment of the 'Underwater Technology Research Center' which opened on 1 April 1999. This new center also plans to collaborate both nationally and internationally with other facilities for further R&D of AUVs and other new underwater observation technologies.

MASA: a multi-AUV underwater search and data acquisition system

Abstract: Nekton Research is developing a cooperative multi-AUV system. This system, multi-AUV search array (MASA), will allow 3D searches and data collection with high spatial and temporal resolution in both inshore and near-shore environments. The paper discusses MASA's design.

Unmanned underwater vehicles

Abstract: AUV: autonomous underwater vehicles ROV: remotely operated underwater vehicles This industry involves companies that manufacture Autonomous Underwater Vehicles (AUV). AUVs are vessels that can travel underwater without an operator on their own source of power. AUVs are used in commercial industries (oil and gas), for military missions as well as for research purposes. This industry provides maintenance services for AUV as well as manufactures AUVs in different configurations for depths less than 200m as well as greater than 200m. Furthermore, the products (AUVs) are divided into three categories: 1. 200 meters+ depth of water (30% of the market) 2. Up to 200 meters depth of water (40%) 3. Up to 30 meters of water (30%)

NAVOCEANO Seahorse AUV design, testing, and capabilities

Abstract: After an initial conceptual design phase, the Applied Research Laboratory at the Pennsylvania State University (ARL/Penn State) began in April 1999 design and construction of an autonomous undersea vehicle (AUV) to specifications provided by the Naval Oceanographic Office of the United States Navy (NAVOCEANO). The first Seahorse AUV was delivered for testing 13 months later. An additional vehicle has been delivered and a third is under construction for NAVOCEANO. This paper describes the requirements for which the vehicles were designed and the actual construction of the vehicle, and presents some examples of the types of missions that have been run.

Recognition of sacrificial anodes using parallel lighting for fully automatic underwater inspection by autonomous underwater vehicles

Abstract: In this paper, an automatic inspection method by AUVs (Autonomous Underwater Vehicles) is proposed. As an example, full-inspection of the bottom shell of IT Mega-Float (a very large floating artificial land which is located at Yokosuka) is addressed. The AUV moves by dead-reckoning navigation, while the position error is reset by a vision-based system using sacrificial anodes as a reference. These anodes are fitted at regular intervals to prevent corrosion of the structure. In order to identify a sacrificial anode that may also be covered with marine organisms, the parallel lighting method is proposed. Simulations of the proposed technique and field experiments have been carried out under the bottom of IT Mega-Float to demonstrate the efficiency of the proposed method.

On the Development of Underwater Docking and Recharging System for AUV

Abstract: The lack of power source capacity is one of the most fatal problems for the AUV spotlighted as a means of underwater survey and observation of the next generation, to be attacked for its practical use. To be free from such a problem, some long-term-cruising-AUVs employ with a large capacity power source like a closed cycle diesel engine or a fuel cell. On the other hand, if underwater recharging system for conventional batteries is developed, that will help us make the AUVs more practical without increasing its size, weight and cost. And such a new method of the AUV can be expected that the AUV is operated in combination with underwater bases or large submersibles.Now, we have carried out to develop such an AUV, called“MARINEBIRD”, that is capable of docking in an underwater station and recharging the battery. This kind of technologies have already been underwatertested in the U.S.A. and European countries, but our newly developed AUV is based on our original mechanism for docking, different from such ones.The MARINEBIRD succeeded the docking test in the dock trial, and demonstrated the excellence of its autonomous docking capability.The MARINEBIRD has the big advantage of charging batteries and receiving data at the underwater base without recovery by the surface support ship or such purposes as required in combination with a larger submersible, that will contribute to increase efficiency in underwater survey.

Tracking control of autonomous underwater vehicles

Abstract: Abstract : Recovery of Autonomous Underwater Vehicles (AUVs) can often be an autonomous operation itself. In the case of an AUV that is launched and recovered at some significant depth below the surface, the recovery platform to which the vehicle will dock is often not a stationary platform. The recovery cage/platform has dynamics associated with it, which are induced by wave motion effects on the ship to which the cage is tethered. In order to successfully recover a vehicle into a cage platform it will be preferred for the vehicle to have the capability to compensate for this motion when making its final approach to the cage. Using active compensation, a smaller cage can be utilized for recovery of an AUV. This research attempts to investigate a means by which a vehicle may be made to track, in depth, dynamic motion with zero phase lag between the vehicle and the recovery platform utilizing an error space controller.

Measurement Methods and Analysis: Forces on Underwater Gliders

Abstract: : Autonomous Underwater Vehicles are unmanned vessel that can used in many applications including offshore oil industry, Marine biology research, and salvaging in an effort to replace divers. As today's Naval Explosive Ordinance Disposal Units look for innovative, technological developments in minefield clearance and related missions clearing unexploded ordinance, the further employment of autonomous unmanned vehicles (AUV) is under strong consideration. Instead of developing systems of high complexity and cost, it is worthwhile to investigate the development of low-cost AUVs with more singular and simplistic missions. This research investigates the design of a miniature efficient underwater glider, of dimensions consistent with the proposed mission. Underwater gliding refers to notion in which the force of gravity provides propulsion and steering is maintained by control fins or by controlling the location of the center of gravity. Wings on the vehicle support its weight underwater and subsequently allow horizontal notion. Different configurations of underwater vehicles will be designed in this study in order to develop a methodology for testing and modeling general underwater gliding behavior. The shape of the wings, their angle of attack, body shape, body size, and vehicle velocity will be factors used in formulating efficient underwater vehicle designs. In this paper, the research describes the design and preliminary analysis of several model underwater vehicles, consisting of a cylindrical body and configurable wings, which were built to demonstrate and test dynamics and control of underwater gliding. This Trident Project can later be expanded to build a prototype autonomous underwater glider after the precepts of underwater gliding are understood.

Research on long range autonomous underwater vehicle

Abstract: We have mainly researched necessary technologies with respect to long range autonomous underwater vehicle (LAUV), described some realizable methods about navigation ,energy and control systems, and drawn some experiment results, provided experiment data and theoretic results for improvement of LAUV in the future.

Semi-autonomous touching of underwater object by unmanned untethered vehicle

Abstract: To investigate an underwater object in detail, it is essential for underwater vehicles to touch the object. However, for the Unmanned Untethered Vehicle (UUV) touching an underwater object is not an easy task because those robots are not apt to be operated remotely via acoustic link which is slow in communication rate and results in a long time-lag. In this paper, on the basis of time-lag compensation by stored video images, ranging technique by image processing and station keeping by visual feedback, a semi-autonomous system is proposed that enables the UUV to touch an underwater object by its hand from any direction. The proposed system is demonstrated experimentally through tank tests using testbed robot Tri-Dog 1 to which a two-degree-of-freedom robot hand is fitted.

Multiple Autonomous Underwater Vehicles cooperative Control System based on Hydrib Architecture

Abstract: Multiple autonomous underwater vehicle (MAUVs)cooperative control system plays an important role in the application of AUVsSuch as the map making of particular areaFor the multiple homogenous AUV system,an open cooperative control system is developedIt has been proved that system is suitable for the implement of the MAUVs controi system through simulationBased on this architecture,a formation control involved three AUVs is successfully performed by simulation test

Advanced Navigation Method of Autonomous Underwater Vehicle using Artificial Underwater Landmark and Deadreckoning

Abstract: Recently, investigation of underwater structure and fresh water environment such as lake and dam which are closely related with human life have got much attention. Even though Autonomous Underwater Vehicles (AUVs) are anticipated to be very useful tools for mentioned missions, problems of conventional navigation method prevent AUVs from accomplishing them. In this paper, a new underwater navigation method for AUVs is proposed based on Artificial Underwater Landmarks (AULs) which are recognized by a vision system implemented in the robot. When an AUV cruises by deadreckoning, position error accumulated gradually depending on characteristics and direction of navigation devices reliability. When the error is within an acceptable range for finding a specific AUL along the track line, the AUV can correct the position and direction by refering to those of the AUL. Then, the AUV continues to cruise by deadreckoning again. Since the underwater vision system is requested to have high reliability, a new un-derwater image processing strategy is introduced based on analysis of underwater vision environment. Configuration of the AUL, shape and color of targets on it are designed to optimize image processing and recognition. Experiments were carried out to demonstrate the efficiency of the proposed navigation method by the intelligent AUV “Tri-Dog1”.

The autonomous underwater vehicle "Pipsqueak"

Abstract: A team of freshman students was presented with the ambiguous challenge of designing an AUV (autonomous underwater vehicle) the size of a wallet. A Micro-AUV would be small enough to avoid many of the transport problems. Because of the potentially simple design of such an AUV, purchase and maintenance costs could be kept fairly low. An AUV such as Pipsqueak would likely be deployed into a lake river, where its size and the environment would allow it to investigate most efficiently. It could also be released in low current ocean areas, such as along beaches or coral reefs. In the future, we predict that as the Micro-AUVs develop and become more efficient and powerful, they might be used for deeper and more intense exploration. In this design, depth is sensed with a pressure gauge such as the Omega DPG1000. Temperature is measured with temperature sensors such as the Seabird 3Bfplus. Images of the surrounding environment would be useful in gathering scientific data. We specified using a CCD or CMOS camera that can interface with the micro controller and satisfy the volume requirements. There are large numbers of low cost, compact digital imaging cameras available today that can be readily incorporated into Pipsqueak. We propose to use the prebuilt RAMCAM from Spectronix. The dead reckoning, inertial based navigation system would be used for this vehicle. This system would have two rear facing horizontal thrusters, and one top facing vertical thruster, which will allow for turning as well as up and down motion.

Current researches on underwater robotics in Korea

Abstract: Inherent to its geographical location, Korea has long been interested in the ocean. As for underwater robotics, several vehicles have been made in Korea since the 1980s. Towards the 21/sup st/ century, the Korean government has established a basic plan for ocean development and preservation named by Ocean Korea 21. The plan contains various R&D programs for ocean environment measurement, ocean resources exploitation and ocean space utilization, in which a variety of underwater vehicles is involved. This paper introduces previous, present and future research on underwater robotic vehicles in Korea.

AUV control in the presence of fin actuator faults

Abstract: Autonomous underwater vehicles (AUV) are rapidly becoming useful and versatile tools in the ocean environment. They have only recently matured to the level of commercial viability, but there is currently recognition of the need for AUV, and an expectation of increased benefit from using these vehicles. In order for AUV to be firmly established as a viable, mature technology there are several issues that need to be addressed, not the least of which is reliability. A systematic study was made involving simulations of a vehicle under fault conditions to identify the vehicle behaviours typical of such fault conditions. The simulation tool used is a linear model of the dynamics of the Canadian Self-Contained Off-the-shelf Underwater Testbed (C-SCOUT), and the maneuvers used were those most likely to be desired during normal operation: holding course, a controlled dive, and a turn in the horizontal plane. C-SCOUT is typical of many current AUV, therefore the results of the study are applicable in a qualitative sense to a number of vehicles.