[in Japanese]

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Civil structures have been deteriorated due to aging or strong ground motions of earthquakes. For the investigation of damage in concrete structures, for example, visual observation would be primarily performed. When performing the details investigation for superstructures, such positive inspection techniques as ultrasonic test, impact echo test and infrared-red radiation test are carried out followed by visual observation, while for substructures, such investigation is generally not applied since their difficulties in applications for experimental cases. Acoustic emission (AE) is a non-destructive technique based on the elastic waves generated due to cracking within materials. The AE technique is applicable for not only to know source identification of defects but to quantify the damage degree. In the present paper, two applications of AE technique for railway structures and rock slope stability are introduced. In both applications, successful ideas to quantify damage are briefly demonstrated.

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Usually Jet-fans are hung from a ceiling of a road tunnel using supporting devices in Japan. Since many vehicles pass under the Jet-fans, falling of any parts or components of the Jet-fans should be avoided to ensure comfortable driving without accidents. Therefore, it is very important to monitor the supporting condition of the Jet-fans for the maintenance. We developed a new monitoring system using load cell that detects the loading condition of supporting devices. This new system uses the load cell to monitor the Jet-fan total operating condition, such as slack of supporting devices, vibration caused by unbalance of the fan blades. Therefore, this system can be applied to maintain the safety operation by continuous monitoring remotely for the suitable maintenance. This paper shows an experimental work that is simulating actual condition of a Jet-fan in a road tunnel and also shows the result of the effect of changes of loading condition. Furthermore, as a diagnostic criterion for the result of monitored condition, we adopted statistical diagnostic method.

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Composite overlapped pressure vessels (COPVs) have been employed for aerospace structures, such as accumulators for satellites and propellant tanks for rockets. Since launching cost of rockets is expensive, and modification or repair of vessels is impossible after launching, many qualification tests are conducted during development. In recent years, COPVS are also applied to automobiles, such as fuel tanks for natural gas vehicles and fuel cell vehicles. In contrast to COPVs for aerospace structures, fuel tanks for automobiles are used in urban area and required to have sufficient safety. In order to assure structural integrity or safety of the vessels, it is better to use health monitoring system not only during qualification tests but also in service. In the present paper, development procedure of COPV is introduced, and needs of structural health monitoring system during development and in service monitoring are described.

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This paper presents a part of feasibility studies of damage monitoring technology using FBG (Fiber Bragg Grating) sensor/PZT actuator hybrid sensing system for aircraft structures. Recently, weight reduction of aircraft is required for the energy saving due to the ecology problem. Therefore, the application of composite material as CFRP (Carbon Fiber Reinforced Plastic) laminate is required. However, composite materials have not yet well application for primary structures, because of the invisible fracture process and highly NDI cost. The structural health monitoring can be useful tool as a one of the verification method of the aircraft integrity and a novel NDI method. In present studies, we presented a concept of the damage monitoring using FBG sensor/PZT actuator hybrid sensing system. FBG optical fiber sensor and AWG type filter used to detect the damage by analyzing the information from elastic wave, which is propagated in material by the PZT actuator. Furthermore, the application area of the novel system was presented based on the results of conceptual aircraft design.

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The surface mounted piezoceramic transducers and fiber optic sensor can detect signals in both symmetric and antisymmetric Lamb wave modes. Hanning windowed sine torn bursts were used for the piezoceramic transducer excitation signals. In order to overcome the difficulties in the signal processing of the simultaneous modes, using the two sensors bonded on the opposite surfaces at the same planner location separated the symmetric and antisymmetric modes. Spectral analyses of the separated symmetric and antisymmetric Lamb waves showed that each mode propagated with different frequency characteristics in the exciting frequency band range. In case of a fiber optic sensor, its geometric characteristics induce sensing directivity of Lamb wave. In this paper, the directivity of a fiber optic sensor was investigated using EFPI (extrinsic Fabry-Perot interferometer) sensor.

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[in Japanese]

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"Mechmech Fair" in Gunma block of JSME is an educational traditional event for young students of elementary school, junior high school and high school in the Gunma area in order to give them an opportunity to observe machines and experimental devices exhibited by the enterprises, the prefectural industrial technology institute, the national college of technology, the vehicle technical academy and the university in this area. Through this experience, we hope that they are interested in the science and technology and they embrace some feelings to be a researcher or an engineer in their future. In this year, the event was held as the tenth anniversary of the foundation of Kanto branch in JSME. This report describes the outcomes of the memorial event.

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The Innovation Center for Research and Engineering Education was founded in the Utsunomiya University in April 2002. The center purports to promote innovative and creative mind for engineering in students. The center also carries out various education programs for pupils in local primary and high schools. The paper describes one of those programs.

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In this paper we propose a mobile mechanism using vibration. Our proposed mechanism consists of two small voice coil motors, several bundles of elastic fibers. These elastic fibers aslant attached to a body of the mobile mechanism change vibration into driving force using the difference of friction force, and elasticity. We measured moving velocity by changing attachment angle of elastic fibers and applied frequency. It is possible that this mechanism can control move direction by independently controlling two motors.

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This paper describes a zero-power magnetic levitation using magnetostrictive (GMM)/piezoelectric (PZT) laminate devices. This magnetic force control is based on the inverse magnetostrictive effect of magnetostrictive material, where magnetization of the GMM hence a magnetic force is control by the applied voltage to PZT. Because the PZT is considered electrically capacitive in steady state, no electric energy is required to maintain constant magnetic force. We performed a magnetic levitation using a magnetic force control device with there laminations of the GMM and PZT. Zero-power consumption of the levitation system in keeping a constant gap was confirmed by the measurement of the input current to the PZT.

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In this paper, we discuss an aerial posture control problem of a 2-link acrobat robot with nonzero initial angular momentum. First, the equations of motion and the law of conservation of angular momentum are shown. Next, the initial and final conditions for Kovacs that are independent from aerial posture control method of the robot are derived. Next, we propose a performance index that shows how easily the robot can catch the bar. Then, using this performance index, we select the optimum initial and final conditions. Finally, a simulation result represents validity of the proposed initial and final conditions.

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The authors developed a Manta-like submergence vehicle which is expected to perform smooth up-down motion. For Manta is conjectured to use only fluid force to keep floating in the water. This vehicle is 0.7 m in length and 1.05 m in width, and has two fins. Each fin has two joints that can move independently by servomotors connected to the joints, and performs pitching motion. Movement of fins is controlled by a microprocessor which is installed on a R/C controller. In a water-tank experiment, this vehicle swan near the water surface at about 0.1 m/s. Better performance and three-dimensional movement will be attained by adjusting motion control.

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A walking assist robot for a blind person is proposed in this paper. An encoder based positioning control was utilized to help a user. The error of the encoder based control was compensated by magnet lines attached on floor of corridor.

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A lizard can move on irregular ground because its center of gravity is low. The walk of robots with such a leg mechanism is very stable. However, in former research, the backbone had been fixed, and the center of gravity moved only by the four legs. The authors manufactured a lizard robot with a flexible backbone. This paper studies the influence, which the motion of the backbone has on a walking.

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