Autonomous Underwater Vehicle R2D4
Kenji Nagahashi, Takashi Obara, Kenji Nakane, Isao Yamanaka and Tamaki Ura
Abstract:
A project of development of an Autonomous Underwater Vehicle R2D4, for survey of seabed in deep water, has been started in 2001. The new vehicle, as the successor of the R-One Robot which is the first large scale AUV in Japan and of the Aqua Explorer series AUV for the submarine cable maintenance, will be launched in March, 2003. The vehicle is 4.4m long and 1.4tonf in weight, and can dive to 4,000m deep. This paper presents the outline of the vehicle's configuration, payload and its intelligent navigation system such that it can change the survey course autonomously when the anomaly from the surroundings is detected.
Autonomous Underwater Vehicles for Seafloor Observatories: Challenges and Opportunities
Dana R. Yoerger, Albert M. Bradley
Abstract:
The capabilities of Autonomous Underwater Vehicles have been steadily increasing in recent years, and they are beginning to make critical contributions to seagoing scientific programs. In many cases, AUVs now operate for extended periods completely independent of a surface vessel, freeing the vessel to perform other tasks. However, nearly all of this work is conducted in a conventional expeditionary style: AUVs are deployed, operate until their on-board energy is consumed, then return to the surface for recovery. Between dives their batteries are recharged, a new mission program is downloaded, and a number of maintenance checks are performed.
Cabled subsea observatories can act as bases for long-term deployment of AUVs, giving them unprecedented capabilities for both extended time series observations and the ability to respond to events. A cabled observatory can provide the high-speed data links required for specifying missions and uploading large data sets as well as the power to recharge batteries. In this paper, we present a series of technological steps to extend our present expeditionary capability to a more sustained presence, which could culminate in observatory-based AUVs. We outline a series of demonstrations; each expected to return new and interesting scientific data that extend our AUV capability incrementally, culminating in a fully autonomous, long-term deployable AUV system.
Nonlinear Dynamic Analysis of a Cable Coupled with an Underwater Launcher
Sup Hong, Hyoung-Woo Kim, Yeon-Gyu Kim, Pan-Mook Lee and Taro Aoki
Abstract:
Korea Research Institute of Ships and Ocean Engineering (KRISO), an ocean engineering branch of Korea Ocean Development Research Institute (KORDI), is under development of a deep-sea unmanned underwater vehicle (UUV) to probe the deep-sea up to 6,000m water depth for the purpose of scientific research. The deep-sea UUV will be also used for underwater observation, sampling, precise works at deep-sea and long-range surveys in the sea around the Korean Peninsula and the Pacific Ocean. Since the UUV requires both functions of ROV and AUV, the UUV will be composed of three vehicles, i.e., a launcher, an ROV, and an AUV. The vehicle will be operated in ROV mode generally. The launcher will be connected to a support vessel with a primary cable, and the ROV will be released from the launcher, of which the operational concept in the ROV mode is same as that of KAIKO of JAMSTEC. The launcher suspended from the end of the primary cable will be equipped with a drum being capable of managing the secondary cable of the ROV. The AUV will be launched in particular situation, such as, when long-range surveys are required simultaneously while the ROV is in operation in deep-sea. Additionally, the launcher will be equipped with a docking and homing device for the AUV, where the AUV will be launched from and docked into the launcher in deep water. The AUV will be able to be re-launched in deep-sea after recharging the battery and saving the data or reloading control programs. The deep-sea UUV, therefore, will be a multiple vehicle system accompanied with the launcher, the ROV and the AUV for multidisciplinary researches in both shallow and deep-sea environments.
A docking system is needed for the recovery of the AUV at deep-sea and a precise navigation system is required to achieve successful homing and docking the AUV. KRISO will design a precise navigation system composed of an USBL (ultra short base line) and a visual camera mounted at the nose center of the AUV. The launcher, however, will show irregular motions due to transmission of the support vessel's motion at surface through the primary cable. It is necessary to obtain a mathematical model for the motion prediction of the launcher. We can predict the terminal position of the launcher when the AUV approaches to the dock after few seconds by measuring the motion of the ship and the launcher.
This paper will present the nonlinear dynamic analysis of the primary cable coupled with the launcher of the UUV. The cable will be idealized as tensional elements ignoring torsional moments and local bending moments, and modeled with discrete lumped masses. The launcher will be modeled as a 6 d-o-f rigid body motion with hydrodynamic coefficients. The cable coupled with the launcher will be modeled simultaneously and a numerical model will be proposed to predict the launcher motion. Time domain simulation will be performed to predict the position and nonlinear behavior of the launcher induced with waves and currents.
Robust Trajectory Control of a Remotely Operated Vehicle for Underwater Inspection Tasks
Jenhwa Guo, Forng-Chen Chiu, Sheng-Wen Cheng, Jun-Wei Pan
Abstract:
The paper describes a design method for trajectory control for an underwaterÅ@inspection system. The system is composed of an ROV, a 200-meter tether cable including power supply cable and signal cables for communications. Master surface PC is connected to a slave PC board inside the ROV via Ethernet. Plug-in cards for control and instrumentation are placed inside the vehicle. Six thrusters using DC motors are used to control depth, position on the horizontal plane, and heading of the vehicle. All controls are closed-loop, and can be commanded manually. The navigational data, sonar image, and video images are displayed on the screen of the surface computer.
The purpose of the trajectory control is to provide the stable tracking to support routine underwater inspections of underwater structures. The user first plans a trajectory for the vehicle, and inputs such as reference orientation and reference velocities are calculated. Then a tracking controller is used to track those input commands. The tracking controller has a structure similar to the well-known PD control and the sliding mode control. The stability of this tracking method is proved through the uses of a Lyapunov function. It was also shown that the tracking error is exponentially convergent. Simple relation between control parameters and the exponential factor was derived. Finally, the effectiveness of the method was verified by experiments. Tank tests and open sea experiments assure that the trajectory control method proposed herein yields satisfactory results.
Visual Observation of Underwater Objects by Autonomous Underwater Vehicles
Hayato Kondo and Tamaki Ura
Abstract:
To investigate underwater objects such as piles and caissons in harbors by taking visual images, Autonomous Underwater Vehicles (AUVs) have advantages that they have no umbilical cable which may get entangled in the target object and surrounding obstacles. It is usually difficult to measure precise configuration of such target objects by using acoustic measurement systems because of poor resolution and diffused reflection of sound. This paper proposes a navigation method for AUVs to observe such objects using a laser range measurement system that consists of a TV camera and laser pointing devices. This ranging system provides precise distance to the target object so that the vehicle can trace the shape of the target object keeping constant distance and attitude. It is assumed that the visibility is adequate for taking visual images of the target. It was implemented in the testbed AUV "Tri-Dog 1," and proved experimentally through tank tests. The vehicle accomplished the observing mission that automatically detects and turn around three pile-objects those are modeled on actual piles in a harbor. This paper also shows the result of sea trials at the port of Kamaishi, Japan. Based on the proposed method, AUVs will find new practical applications of autonomous observation of underwater objects.
Yan Kuichen, Yuan Xueqing, Qin Baocheng
Abstract:
With a view to deploying the guidance ropes to the faulty ships under the severe sea state and carrying the life rescue rings to the dropping people quickly, we have developed a rescue surface vehicle which could tow the guidance ropes and life rescue rings. This vehicle would possess with the characteristics such as strongly wave-surge resistant capability, small volume, light weight, high speed, and dexterous flexibility. When the rescue vehicle accomplishes the task to send the guidance rope, the rescue ship or the faulty ship, depending on the specific conditions could recover it.
The control system for the rescue surface vehicle would consist of both surface operation part and vehicle motion control part; the radio telecontrol mode would be used for the communications between two parts; the vehicle motion in water would be telecontrolled by the manipulator; this paper pays attention to discussing some problems involved in design of control system and communication system.
To overcome the impact from large surges, high waves, and strong current under the severe sea state, the rescue surface vehicle has adopted the upper-lower double-body isolated structure with the stream line type.
Because the rescue surface vehicle has to tow the guidance ropes or life rescue rings under the severe sea state, It is vital for us how to choose the most suitable for propulsion of this vehicle. So we have done a series of experiments about relations among drag and different shapes and speed, and we get drag curves under different speed and effective power required for vehicle, according to these experiment results, we modify theoretical calculation results and match with the most suitable propulsion.
Through ocean experiments the following several basic results are drawn, these experiment results refer to in stability, operability and surface towing capability. For the applied ranges of the rescue surface vehicle, it is not only applied to carrying the ropes, sending life rescue rings, emergent rescue, and transferring major goods and materials under the severe sea state but also to the other applied cases.
Cable Tracking by Autonomous Underwater Vehicle (P)
Junichi Kojima
Abstract:
This paper will describe cable tracking method and recent activities of Autonomous Underwater Vehicle named AQUA EXPLORER 2 (AE-2) and AQUA EXPLER 2000(AE2000) which were developed for the inspection of submarine cables.
AE2000 can find and trace underwater telecommunication cables by using a cable tracking sensor. While tracing the cable, and can measure the burial depth of cables. The continuous operating period is more than 16 hours with velocity of 2 knot. Its weight is 300 kilograms.Cable tracking function is used for measurement of the burial depth of submarine cables, and inspection of submarine cables. If the electric wire is laid on the seabed along with the investigation route in advance, this AUV can repeat and trace the same route. This function is very convenient to investigate the regular route repeatedly.
Last winter, authors conducted an experiment for cable tracking in a shallow bay where the electric wire was laid in the shape of a loop from the wharf. AE2 launched from the wharf, traced the cable, and return to the start position successfully. While AE-2 cruised, many data was measured.
This experiment shows that AUV is useful for the platform of mobile sensors.
Development of AUV "Marine Bird" with Underwater Docking and Recharging System (P)
Tadayuki KAWASAKI, Toshihito NOGUCHI, Takeo IIMORI, Toshifumi FUKASAWA, Yozo SHIBATA, and Makoto BAINO
Abstract:
Kawasaki Shipbuilding Corporation, affiliate of Kawasaki Heavy Industries, Ltd., has developed an experimental autonomous underwater vehicle (AUV) "Marine Bird" capable of docking with a fixed or mobile underwater base to recharge its batteries.
The Marine Bird can be a powerful tool for underwater observation cable network system. That is, using the Marine Bird as a maneuverable observation unit, the underwater observation cable network system can extend its observation area. The Marine Bird can also be used as a messenger between a local (closed) cable network system and other network systems. On the other hand, the Marine Bird can extend its duration and observation capability by using the underwater observation cable network system as an energy station and data trading terminal.
Today there are several kinds of AUVs in the world. Although they are used for many purposes, such as oceanography data measurement, sea floor mapping, water sampling, and underwater cable maintenance, they have some common issues to get through. One of the most important elements is to enhance the duration, especially for battery-powered AUV. Battery-powered AUV has to often surface and be lifted up on its support vessel to recharge the batteries, which results in wasting much time and manpower. In case of long term monitoring, the cost to deploy a support vessel is particularly large.
The underwater docking and recharging method is a prospective solution to clear up such a problem. The technology of this method will reduce the necessity for surface supports greatly. By docking to an underwater base connected to an on-shore control center or so, AUV can receive energy from an external source, can send data AUV has collected, and can be loaded with a new mission AUV should carry out next. AUV can also correct its position data using the base location.
Although some underwater docking and recharging methods have been contrived and proved in the U.S. and Europe, we have developed the Marine Bird based on our own concept. The concept is that the structure of the underwater base should be as simple as possible without mechanical moving parts so as to reduce the necessity for its maintenance. And we contrived the landing-to-base method. On finishing its mission of exploration, the Marine Bird moves near to the underwater base, approaches with its two catching arms dragging on the strip way of the base, catches the V-shaped guide on the base with the catching arms, moves downward, joins its connecting device, and charges batteries. Although this method is similar to the landing method of aircraft on aircraft carrier, it has some remarkable points, which are; 1) the Marine Bird has to dock autonomously; 2) the Marine Bird needs to dock to a precise point on the base to connect with and receive energy; and 3) the underwater base for the Marine Bird does not transmit leading commands when docking.
This paper introduces an outline of the Marine Bird, its docking and recharging system, and the results of its test trials.