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The information on the frictional resistance of a self-propelled robotic capsule endoscope moving inside the body is very important for the design and the performance enhancement of such parameters of the capsule endoscope as power consumption, motion control and positioning accuracy. Based on this motivation, the ultimate goal of this research was to develop an analytical model that can predict the frictional resistance of the capsule endoscope moving inside the living body. In this work, experimental investigations of the fundamental frictional characteristics and the viscoelastic behaviors of the small intestine were performed by using custom-built testers and various capsule dummies. The small intestine of a pig was used for the experiments. Experimental results showed that the average frictional force was 10-50 mN and higher moving speed of the capsule dummy resulted in larger frictional resistance of the capsule. In addition, the friction coefficient did not change significantly with respect to the apparent area of contact between the capsule dummy and the intestine, and also the friction coefficients decreased with an increase in the normal load and varied from 0.08 to 0.2. Such frictional behaviors could be explained by the lubrication characteristics of the intestine surface and typical viscoelastic characteristics of the small intestine material. Also, based on the experimental results, a viscoelasticity model for the stress relaxation of the small intestine could be derived.KEY WORDS: biotribology, capsule endoscope, small intestine, stress relaxation, viscoelasticity Nomenclature F Friction force (N) l Friction coefficient N Normal force applied to the capsule (N) r(t) Stress applied to the small intestine (Pa, N/m 2 ) 0Strain applied to the small intestine t Time

Research on the improvement of efficiency in the manufacturing industry is underdeveloped partly because of the ambiguous objectives of the technical development of efficiencies in terms of energy consumption reduction. Consequently, the technical development of high-efficiency techniques that consider the whole manufacturing system is rarely addressed in industrial research. For this reason, this report aims to find the patterns in, and the definitions of, the technologies that will lead to efficiency improvement in the entire manufacturing industry by thoroughly investigating the literature about energy consumption reduction strategies, energy policies, and the state-of-the-art for energy-saving methods that are being pursued currently in several major countries. Through this study, the necessity and importance of the foregoing three items have been identified, and a way of defining the productivities of an energy-saving manufacturing system distinct from those of conventional manufacturing systems was attempted. It is also shown that the development of energy-saving and energy-harvesting technologies for all industrial sectors has emerged as a herald of economic growth in the near future.

For the purpose of optimizing the design of the locomotion mechanism as well as the body shape of a self-propelled capsule endoscope, an analytical model for the prediction of frictional resistance of the capsule moving inside the small intestine was first developed. The model was developed by considering the contact geometry and viscoelasticity of the intestine, based on the experimental investigations on the material properties of the intestine and the friction of the capsule inside the small intestine. In order to verify the model and to investigate the distributions of various stress components applied to the capsule, finite element (FE) analyses were carried out. The comparison of the frictional resistance between the predicted and the experimental values suggested that the proposed model could predict the frictional force of the capsule with reasonable accuracy. Also, the FE analysis results of various stress components revealed the stress relaxation of the intestine and explained that such stress relaxation characteristics of the intestine resulted in lower frictional force as the speed of the capsule decreased. These results suggested that the frontal shape of the capsule was critical to the design of the capsule with desired frictional performance. It was shown that the proposed model can provide quantitative estimation of the frictional resistance of the capsule under various moving conditions inside the intestine. The model is expected to be useful in the design optimization of the capsule locomotion inside the intestine.

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The design of the capsule body for a self-propelled endoscope is important from the frictional resistance point of view. The motivation of this work was to gain a better understanding of the effect of capsule shape on the frictional resistance of the capsule inside a small intestine. Special experimental set-ups were built to investigate the frictional resistance of the capsule and the viscoelastic deformation characteristics of the small intestine specimen of a pig. Tests were performed with capsules of various shapes and dimensions. Experimental data showed that a smooth cylindrical capsule geometry resulted in the least frictional resistance due to the shape and relatively small surface area. Also, it was found that the variation of frictional resistance of the capsule was closely related to the local change in the viscoelastic property of the intestine due to the heterogeneity of the internal structure of the intestine.

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