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TECHNICAL ASSESSMENT OF
TWO UNMANNED VEHICLES FOR
UNDERSEA RESEARCH

Two new Japanese developments in undersea technology were evaluated
during sea trials: a semi-autonomous vehicle and a new, low-light-level
camera for a remotely operated vehicle. The semi-autonomous vehicle, or
UROV (Untethered Remotely Operated Vehicle), was attached to the surface
with a 1-mm fiber optic link. The low-light-level camera, named HARP
(High-Gain Avalanche Rushing Amorphous Photoconductor), was deployed
on a 3,000-meter ROV and is a next generation for underwater camera low-
light capability. Both systems tested well and are assessed below.

INTRODUCTION

by A.N. Kalvaitis and Gregory Stone

Program in Natural Resources (UJNR).
Mr. Greg Stone, a guest researcher at
JAMSTEC, is on exchange from the
National Oceanic and Atmospheric
Administration's (NOAA) National
Undersea Research Program (NURP).
The other author, Mr. A. Kalvaitis, is a
senior engineer at NOAA-NURP in
Silver Spring, Maryland. Cruise partic-
ipants included several engineers, among
them Dr. Matsuo Hattori of JAMSTEC,
and researchers from other Japanese
agencies and companies.

Proof-of-concept sea trials of two
different undersea vehicles, developed
for undersea research, were observed
on 6-7 November 1991. These evalua-
tions were conducted on the UROV-
500, a battery powered remotely oper-
ated vehicle (ROV), and the DOLPHIN
3K ROV, using an ultra-sensitive under-
water color video camera. These tests
were conducted in the western part of
Sagami Bay near Hatsushima Island
off Atami, Japan, using the R/V KAIYO
and R/V NATSUSHIMA as surface BACKGROUND
support vessels. The Japan Marine
Science and Technology Center
(JAMSTEC), the primary institution
in Japan dedicated to ocean research,
was responsible for carrying out these
investigations.

PARTICIPANTS

The authors were invited by JAMSTEC to witness these sea trials under the auspices of the Panel on Diving Physiology and Technology of the United States-Japan Cooperative

The purpose of observing these tests was to technically assess the capability of these vehicles to satisfactorily conduct undersea research. NURP directs a program that is the United States civilian focus for meeting the undersea research requirements of government, academia, and industrial communities. In-situ facilities available to this program include manned submersibles, research habitats, and unmanned systems such as ROVS and autonomous

undersea vehicles (AUVs), as well as bottom observatories.

These capabilities enable scientists to collect data, make observations, collect samples, and conduct experiments not possible within the limitations of traditional laboratory and shipbased research. Most of the research supported worldwide has been conducted from manned submersibles to depths of 6,000 meters, although there has been a trend toward the utilization of unmanned vehicles such as ROVS and AUVS (Ref 1 and 2).

UROV-500 DESCRIPTION
AND ASSESSMENT

The UROV-500 is basically a tetherless, battery powered ROV that uses an expendable fiber optic link to transmit video and other data from depths to 500 meters. These tests were conducted on 6 November, near Hatsushima Island in western Sagami Bay off the JAMSTEC support ship R/V KAIYO. More detailed information on the KAIYO, a semisubmersible twin-hull ship, 61.5 meters long, that allows for

stable at-sea operations, can be found in Reference 3.

This ship, a highly capable saturation diving vessel, can also deploy the DOLPHIN 3K as well as other ROVS. The KAIYO can be held stationary during dive operations by means of a four-point mooring or by dynamic positioning. While in the dynamic positioning work mode, a computer tracking system maintains the ship's position from bottom-mounted transponders or land-based systems. Actual movement of the ship is controlled by bow and aft thrusters and the KAIYO's twin screws.

JAMSTEC has been developing fiber optic linked, battery operated, untethered ROVS since 1986. One of these systems, termed the UROV-2,000, is designed for operations to 2,000 meters and completed successful sea trials in 1990 (Ref 4). These tests demonstrated the functional ability of a self-powered, expendable, fiber optic based vehicle. The 0.9-mm-diameter fiber optics were deployed successfully, and data were collected on system performance. A maximum depth of 515 meters was reached during seven dives.

control signals. System components include a control van, A-frame launcher, the fiber optic cable assembly, and the vehicle itself. The fiber optic cable consists of two spoolers: one is in the vehicle and the other is on the ship. Each contains 1,500 meters of graded index (G.I.) fiber optic cable. Both can uncoil independently if there is excess loading (1 kg tension), and the operation is similar to an expendable bathythermograph (XBT). UROV-500 specifications are as follows:

Depth
Size

Weight
Speed..

Batteries

500 m

2 (L)x1 (W) x 1 (H) m
450 kg
1 m/s (max)
0.5 m/s (cruise)
Ni-Cd, 100 V 20 AH,
24 V 20 AH
2 x 500 W (F/R)
2 x 250 W (U/D)

Instrumentation ...... CCD color TV, black &
white low-light TV, light
x 3, still camera (36
exposures), strobe,
temperature sensor,
transponder, radio
transmitter
Expendable optical fiber
cable, 0.9-mm diameter,
1,500-m long x 2 (vehicle
and ship)
Three-wave length
division multiple optical

Cable

An extension of this development has been the design and construction of the UROV-500, which has a similar configuration but a depth limitation of Transmission 500 meters. This vehicle (see Figure 1) will ultimately be used for fisheries surveys in the Japan Sea off Fukui Prefecture. Two tests were witnessed on 6 November: the first successful deployment reached 300 meters, while the second achieved a maximum depth of 501 meters.

The UROV-500 was developed in a cooperative effort between JAMSTEC and Sumitomo Heavy Industries and Sumitomo Electric Industries. The vehicle is self-powered using Ni-Cd batteries and an expendable fiber optic cable to transmit video, sensor, and

transmission

The first deployment was interrupted by a fault in the fiber optics. Retrieval was conducted without incident, and the cable was repaired using an optical fiber fusion splicing machine. An optical time domain reflectometer isolated the break, and it was spliced within 30 minutes after recovery. The UROV500 was subsequently redeployed and reached a 300-meter depth. The video quality of the transmitted pictures was excellent. During launch operations,

winds were 14 m/s (28 knots) and whitecaps were observed. It is theorized that these windy conditions could have contributed to the fiber optic fault.

The second trial was in the afternoon and the vehicle achieved the design depth of 500 meters. An 11-kg dropweight controlled the descent velocity (approximately 64 cm/s), and the weight dropped near the bottom. After a 45-minute survey at depths from 487 to 501 meters, the vehicle was recovered without incident. This demonstration confirmed that a self-powered vehicle, having expendable fiber optics, offers significant promise for undersea research applications.

UROV's salient features of high quality video and excellent maneuverability combine to provide a suitable platform for visual transects and inspections related to various undersea tasks. In addition, such a design configuration would provide a much larger lateral capability than conventional ROVS and allow excursions into presently inaccessible environments such as under-ice regions. Operational advantages of the UROV include the elimination of heavy duty deck handling equipment associated with typical largediameter ROV umbilical deployments. Secondly, operational constraints associated with flow-induced cable drag typical of long, large diameter ROV umbilicals are significantly reduced.

It should be pointed out that the present fiber optic platforms developed by JAMSTEC are also being utilized as testbeds for advanced AUVs. Research is underway on communication and control methods that will allow the elimination of the fiber optic cable linking the support ship with the selfpowered vehicle. JAMSTEC is developing a color video transmission system that will be capable of sending one frame per 6 seconds over distances of up to 7 km.

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DOLPHIN 3K DESCRIPTION AND ASSESSMENT

The DOLPHIN 3K ROV (Figure 2) is a 3,300-meter-deep vehicle designed for undersea science applications, especially marine geological. The DOLPHIN 3K was designed and developed by Mitsui Engineering and Shipbuilding Co., Ltd. (MES) for JAMSTEC. It has been utilized since 1987 for various scientific applications to depths of 3,429 meters.

Major shipboard components include a control/navigation van, a deck handling system including a heave compensator, and a winch for the 5,000-meter-long,

30-mm-diameter ROV umbilical. ROV capabilities include broadcast quality TV video via optical fiber cable, master-slave sevenfunction manipulator, a five-function

Several tests were conducted. A color screen for visual experiments was deployed in 1,250-meter water depths. Various combinations of light levels and distances were verified. Distributions of Calyptogena communities on the seafloor were readily observed at a 10-meter range using lighting from two 500-W halogen bulbs.

SUPER-HARP COLOR TV CAMERA

JAMSTEC has sponsored development of a low-light-level color video camera for use on the DOLPHIN 3K. The camera uses three camera tubes that were designed by NHK Science and Technical Research Laboratories. This camera is termed a Super-HARP camera (High-Gain Avalanche Rushing Amorphous Photoconductor). It is theoretically 100 times as sensitive as conventional tubes; this allows not only ultra high sensitivity but also excellent picture quality, low noise, high resolution, low photoconductive lag, and no burning (Ref 5). The specifications of the Super-HARP camera are as follows:

Horizontal resolution

manipulator, conductivity/temperature/ Minimum luminous depth (CTD) sensors, and various sampling containers and tools (Ref 1).

The ROV is designed so that it can be deployed off either the R/V KAIYO or the R/V NATSUSHIMA. Another application of the DOLPHIN 3K ROV is to serve as the rescue vehicle for the submersible SHINKAI 2000 that is operated by JAMSTEC. The ROV also has been used for predive surveys in support of the SHINKAI 2000.

The DOLPHIN 3K was installed on the R/V NATSUSHIMA for test dives on 7 November, also near Hatsushima Island, for the purpose of evaluating a high-resolution, low-light-level TV camera. In addition, samples of giant clams (Calyptogena) were observed and recovered by the ROV sampling and collecting equipment.

intensity S/N ratio...

Outer diameter & length Operational depth.........

>600 lines

0.8 lux (9 dB up) >60 dB

184 x 632 mm >3,300 m

Another purpose of this assessment was to observe the undersea science capabilities of the DOLPHIN ROV. The ROV was efficiently deployed and retrieved using the A-frame on the stern of the NATSUSHIMA. The ROV performed video and photo survey transects 1 to 5 meters off the seafloor and collected approximately 20 clams using the manipulator and a wire mesh scoop. The clams were placed in an insulated container for further study. This same site has been surveyed extensively over the past several years using the ROV,

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and there are several long-term experiments underway on the seafloor.

[graphic]

CONCLUSIONS

Both the UROV-500 and the DOLPHIN 3K ROV performed well during the operations observed. The UROV design, which combines fiber optic technology and onboard power, eliminated problems associated with long, bulky umbilicals. It is envisioned that various mission-specific fiber optic type vehicles will be developed in response to science needs, will be relatively low cost, and will operate in areas inaccessible to manned submersibles, i.e., under ice environments. This design configuration allows for large lateral excursions that are unattainable using conventional ROVs. Planned elimination of the fiber optic link over the next few years will provide autonomy to the design but will likely increase costs and complexity.

The DOLPHIN 3K is an excellent undersea research platform and is a valuable supplement or, in some cases, replacement to manned submersible operations. With a depth rating of over 3,000 meters combined with sampling capability, excellent video, CTD, and sonars, the DOLPHIN 3K has numerous salient features for undersea research applications. The newly developed Super-HARP low-light-level TV camera provided excellent color picture quality and high resolution under various lighting conditions. Superior visual acuity is an important criterion for unmanned platform science operations.

A major advantage of the SuperHARP TV camera is the field of view, both width and depth, that the camera provides without a requirement for large separation of the camera and lighting to minimize backscatter. Prior to the development of this system, underwater TV cameras required high intensity lights that sometimes resulted in a narrow field of view and distracting backscatter from suspended particulate matter.

Figure 2. DOLPHIN 3K ROV.

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Moreover, if a low-light-level camera is used, the resolution and picture quality are degraded. Immediate applications of the Super-HARP camera JAMSTEC will be to map the hypothermal vent fields near the Okinawa Trough. In the past, it has been difficult to identify and navigate this complex field of "chimneys"; the Super-HARP camera will allow the detailed mapping

of the seafloor macrostructure using the video images.

Beyond this initial application, the uses for the Super-HARP camera are virtually unlimited. The ability to see at greater distances, at a wide field of view, and at a suitably high resolution will aid all disciplines of undersea research conducted from unmanned and manned platforms.

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