Intelligent Autonomous Underwater Vehicle r2D4 for Deep-Sea Operation
Intelligent Autonomous Underwater Vehicle r2D4
July 23, 2003
Underwater Technology Research Center,
Institute of Industrial Science
The University of Tokyo
1. Introduction
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Since 1984, Underwater Technology Research Center (Head: Professor Tamaki Ura), Institute of Industrial Science, the University of Tokyo has developed several Autonomous Underwater Vehicles(AUV, see #1) of various types and purposes (refer to http://underwater.iis.u-tokyo.ac.jp) and successfully achieved a few meaningful undersea missions. Some of representative examples are the full autonomous survey of Teisi knoll by the AUV "R-One" (see #2) in 2000, construction and field operation of Tantan, which was developed by the environments monitoring of lake Biwa in the middle of Honshu, Japan and experiment of humpback whale chase by AUV. As these examples explain, we are still challenging to broaden the practical applications of autonomous underwater vehicles. By these efforts, as the intelligent machine exploring the underwater region, AUV is becoming more and more a practical mean to survey and exploit the mysteries of undersea realm.
Based on the successes in development and field operations of AUVs in IIS, the university of Tokyo, we established a next generation AUV project named "r2D4" (see #3). This project is supported by Japan Society for the Promotion of Science(JSPS), as a scientific research awarded project grants-in-aid for "Development of Intelligent Autonomous Underwater Vehicle for Deep-Sea Operation" (see #4).
Purposes of this projects are summarized as follows;
- After developing a highly-intelligent and highly-reliable AUV, it is deployed in the undersea region with the mission of surveying undersea hydrothermal vents.
- During this survey mission, not only survey data containing the records of surrounding physical states near the vent spout, but the sequential data from vehicle operation are also recorded and fed back in order to improve the system architecture of r2D4 by getting rid of the expected problems for deep-sea operation.
Repititions of this feedback procedure shall make r2D4 converge to the optimized system architecture for deep-sea hydrothermal vent exploration and result in the newly proposed undersea region survey system supported by the Autonomous Underwater Vehicle r2D4.
Costruction of hardware system as well as primary software system are completed in July, 2003 (Hardware Construction: Mitsui Engineering and Shipbuilding(MES), Co., Ltd.). The first field operation was conducted at the nothern part of Suruga bay, dated 7th July. During 15th - 17th July, the second field operation was held at the offing of Sado island, located in sea of Japan. This field work was done by the joint cooperation with underwater device department of MES. During this underwater operation, r2D4 tracked the pre-designated way points keeping the trajectory deviation sufficiently small. Due to the successfully achieved trajectory tracking control, r2D4 succeeded in taking the high-quality images of undersea geography by the side scanning sonar operation. In addition, measurement of CTDO was also carried out during this operation.
Though the main purpose of development is the survey of undersea hydrothermal vent, deployment of r2D4 is expected to enable several undersea missions such as seeking for lost articles in undersea, surveillance of undersea volcanoes, swimming animals watching, cooperative survey with undersea station and etc., because it has realized the handy system architecture with small size. And in december 2003, r2D4 is planned to be deployed in the Okinawa trough in order to survey the underwater hydrothermal vent near that region.
2. Introduction to r2D4
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In the development of r2D4, key technologies acquired throught the development of R-One, the predecessor of r2D4, is directly applied. Owing to this technical inheritance, r2D4 is completed only within two(2) years with excellent vehicle performances, which is extremely short period compared to other AUV development projects in the world.
1) Characteristics of r2D4
- Compact size and light weight (length overall: 4.4(m), weight: 1,600(kg))
Due to its compactness, r2D4 does not require the large size support vessel. And since its operation can be completed fully autonomously, neither does it require operational experts.
- Self-Completeness
Laborious supports such as transponder installation are not neccessary
Accurate positioning by the combined instrumentation of optical gyroscope and doppler sonar
High reliability and safety
- By the simultaneous manipulation of the data from multiple sensors(sensor fusion)
r2D4 has superior recongnition ability on the complicated underwater environments transition
- Flexible and dynamically adaptive path planning ability for the observation.
If the vehicle finds out a suspicious place or an object in underwaer space, it can re-generate the target path dynamically in order to make this observation.
2) General Missions of r2D4
Observation by AUV is realized by tracing the successive way poionts arranged previously. One of the most common observation activities by AUV is the construction of 3-dimensional seabed topology or wide-range surveillance of undersea region using side scanning or interferometry sonar. Provided an abnormality is detected during the observation, r2D4 re-plans its cruising trajectory and makes the detailed observation in order to clarify the causes of recognized abnormality.
3) Comparion with "R-One", the predecessor of r2D4
Since it is designed compact and small, r2D4 does not require a support vessel which has several functional capabilities. Despite its compactness, r2D4 has much redundancy in its payload to install various equipments for observation. R2D4 is designed to be capable of submerging up to 4,000(m) of depth, aiming at the observation of undersea hydrothermal vent near Marina trough in midwest Pacific.
In the following table, we summaraize key items of r2D4 compared with those of R-One
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