Kanjuro Makihara
(Tohoku University, Japan)

This paper presents autonomous power scavenging using a self-powered control device. This scavenging device can obtain electrical power from structural vibration via the piezoelectric transducer affixed on the structure. The transducer is connected to an electric circuit composed of selective switch circuit. The switching system scavenges power effectively. A processor is driven by the scavenged power, and it changes the switch point according to the switching logic. The device is closed in power flow, meaning that external power resource is not necessary at all. When the structural vibration becomes large, the scavenged power increases, and accordingly, the processor wakes up to scavenge power. On contrary, when the vibration reaches to a small level, the processor starts to sleep and wait. This behavior of the power scavenging system depending on the magnitude of vibration is very reasonable. There are many structures in sparsely-settled region that are subject to vibration and are, however, unable to exploit any external power-supply in light of energy-saving and bothersome wiring. Example structures are space structures, lengthy bridges, constantly streaming factory walls, noise-protective walls. This paper explains the autonomous power-scavenging device and demonstrates the experimental results. The validation experiment shows various aspects and its extendability.

Kenji Minesugi
(JAXA, Japan)

Improvement of acoustic environment on satellites or electrical components is one of key technology to improve their reliabilities and reduce cost for their developments. One of practical applications for acoustic damping is an acoustic blanket attached to inside wall of a nose fairing of a launcher. However, it is known that the acoustic blanket is not so effective on a lower frequency sound pressure below about 500Hz. In order to reduce the sound pressure in this lower frequency range, we propose to apply energy-recycling semi-active control method using piezoelectric transducers on nose faring. In order to investigate an effectiveness of the method, an experiment to reduce sound pressure transmitted through a honeycomb sandwich cylinder, which is general structure of the nose fairing, was executed. The results showed that the energy-recycling semi-active control method was effective on the acoustic damping. It was also found that the locally bonded piezoelectric transducers reduced the sound pressure transmitted through the cylinder wall without the transducers.

Hironori Fujii
(Kanagawa Institute of Technology, Japan)

Study of dynamical behaviour of the system is a necessity as well as the development of materials of the tether. The purpose of this study is to propose a fundamental dynamic model of the space elevator system that is assumed to be a very long tethered system. The equations of its motion considering exibility of the tether are expressed by using the distributed parameter system. The tether length is more than the geostationary altitude due to necessity of counterweight in equilibrium. The taper function that would provide constant stress throughout the tether is treated to determine the diameter of the cross-sectional area. Firstly, the effect of initial displacement and orbital perturbation as a disturbance on dynamics of the space elevator system is studied by numerical simulation. The effect of a climber transit with constant speed is also sutudied on the system. Although the vibration of the tether during ascent and descent of the climber is attenuated, the translational motion of the system is excited similar to the case of the impulsive force. Results of numerical simulation show that the effect of disturbances on the space elevator system has much effect on designing such huge system.

Keita Satoh
(Nihon University, Japan)

This talk presents study on fundamental dynamics characteristics of space elevator system. The tension of space tether system consists of on-orbital gradient of gravity and centrifugal force. Generated tension and stress grow, as tether becomes long. These forces become a critical restriction for the design of such system consists of very long tether. In this talk, the space elevator is introduced as a very long tether system and some perturbations on its dynamics are studied in their effect on the vibration of such a big system. The system is studied both analytically and numerically and both results are compared. In the present examination, Perturbations are included into consideration as the solar radiation, G2 terms in the gravitational field and also the effect of the Sun and moon. These effects are applied to the space elevator and the fundamental dynamics is examined. In addition, a new analytical procedure is employed in t to reduce the effort in the numerical analysis by employing changeable size in the difference elements.

Masatoshi Hatano
(Nihon University, Japan)

This paper is concerned with a self climbing mechanism for the space elevator. The mechanism is required to have driving and pinching functions at least. The driving one is used for making the climber climb up and down along the tether. The pinching one is needed for that the climber does not slip down the tether. Here, it is noticed that the weak pinching force occurs slip down the tether and strong pinching force increases friction forces between the driving wheels and the tether. Thus, it can be said that the climbing mechanism decides the most of the performance of the climber. Then, there are possibilities to propose various kinds of mechanisms. In this paper, we show our constructed climber model. This climber has the PWS type mechanism with two driving wheels like a mobile robot. In addition, its pinching force for can be changed with two passive wheels. Then, the climber can control its position and orientation with the mentioned mechanism. Finally, we show experiment results using our constructed climber model in order to confirm the validity of the proposed system. In the results, it climbed up and down along the tether in up to 300 meters high.