自律型海中ロボット (Autonomous Underwater Vehicle: 以下AUVと呼ぶ) “r2D4” (アールツーディーフォ) は長距離航行型AUVであり, 重量1, 600kg, 全長4.4mで2003年に建造された.観測装置として, サイドスキャンソーナー及びインターフェロメトリソーナー, CTDO, またマンガン濃度を計測する為に現地型化学分析装置GAMOSを装備している.これまで我々は佐渡島 (2003) や黒島海丘 (2003) , 海底火山の北西ロタ (2004) , 海底クレータである明神礁 (2005) などで運用し, 厳しい環境下におけるその自律性と信頼1生の高さを示してきた.2006年12月における白鳳丸航海 (KH06-4 Leg3) では, 中央インド洋海嶺地溝帯のセグメント15及びセグメント16においてr2D4の運用を行った.まず, 始めにr2D4は北緯19度34分, 東経65度51分におけるRoger Plateau (仮名) の調査を行った.ここでは3回潜航行い, いくつかのマンガン濃度の異常を検出したが, これらの発生源を特定するには至らなかった.次に, セグメント16の中央に位置する狭い渓谷での調査を行った.地磁気計のキャリブレーションを行った後, AUVは崖を飛び降り, 深度2, 700mの渓谷の底に辿り着いた.r2D4は渓谷の底に沿って平均3.3ノットで約6時間潜航を行い, およそ25km²におけるサイドスキャンイメージを取得した.サイドスキャンイメージからそこにおよそ26kmの長さで平均2.7kmの幅を持つ, 総面積約70km²の溶岩大平原が存在している事が分かった.平原地帯の北部には小さな岩山があり, その上空を通過した時にマンガン濃度と濁度の顕著な異常が検出された.続いて行われたTow-yoによる調査をもとに, この場所で熱水活動が起こっているという結論に達した.以上の結果から, 事前に綿密なAUV航路計画を行う事で, 航行型AUVは複雑な地形形状をもつ中央海嶺においても強力な調査ツールになりうるという結論に達した.

抄録全体を表示

This paper describes the research and development of a robotic fish. Recently, the development of high performance robotic systems have multiplied across several fields. The development of a robotic system is based on the fusion of many technologies; such as mechanical engineering, electric/electronics engineering, telecommunication engineering, biology, physics, chemistry and so on. For the integration of several technologies we have to proceed from various points of view. The author has developed many such robotic systems, especially in the underwater field. This paper shows the current situation of research and development into robotic fish. This new field is attracting a lot of attention worldwide as we look to the next generation in robotics.

抄録全体を表示

The bore distortion is increased during the head gasket installation. The bore distortion tends to become high for light weight engines and the problem has become important in recent years. In the present study the cause of the bore distortion is discussed. It is related to the sealing pressure generated by the head gasket. Also discussed is the bore distortion in the region between the cylinder bores, which has a typical bore pattern, in light weight engines. It is controlled by using a reinforcement plate in the gasket structure, that is, by adjusting the sealing pressure.

抄録全体を表示

The integrity and safety of a bolted joint are to be guaranteed by applying and maintaining an appropriate amount of bolt preloads. However, the variation of bolt preloads inevitably occurs in the service condition due to various reasons, even if the initial bolt forces are properly applied. Accordingly, the monitoring of bolt forces in the service condition is significantly important. From the practical point of view, it is preferably conducted without disassembling the objective bolted joint.
In this paper, Electromagnetic Vibration Method is introduced for monitoring the variation of bolt preloads in the service condition, and its performance is examined by experiments using bolted joints with various geometric configurations. Electromagnetic Vibration Method estimates the magnitude of bolt force by measuring the resonant frequencies of the bolted joint, which vary in accordance with the contact pressure of the joint interface. Electromagnetic Vibration Method is found to be effective to estimate the bolt force with a reasonable accuracy, except for the bolted joint including the interface under very high contact pressure. In addition, the characteristics of the method are evaluated as a vibration problem by constructing a free vibration model composed of two masses and three springs.

抄録全体を表示