[in Japanese]

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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.

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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.

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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.

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