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en: Estimation of a Force to Structures using SVD and Regularization method (Consideration of Location Estimation of an Excitation Point)

ja: 特異値分解と正則化法を用いた構造物に対する加振力の推定(加振位置推定についての検討)

en: Japan society for mechanical engineers D&D2022

ja: 日本機械学会D&D2022論文集


en: Study on Simple Vibration Control for Small-Size Helicopter with Slung Load System (Experiment Based Studies of the Vibration Control on Hovering)

ja: 小型ヘリコプタにおける吊り下げ物体の簡易振動制御に関する研究(ホバリング時の振動制御の実験的検討)

en: This paper describes a simple vibration suppression control method for a small-size helicopter with slung load system. The vibration suppression control for slung load is essential to improve stability of the flight because weight of a helicopter is relatively light. In past studies, the subject is analyzed by using the model which is a couple of rigid bodies containing a helicopter and a slung load, and controlled by state feedback combined with some sort of estimators. It requires accurate model and system parameters. However it is difficult for general users to build an appropriate model and to identify system parameters in terms of small-size helicopters. In this work we develop a simple control method which superposes vibration control of slung load on postural control of helicopter. By using delayed feedback, we can suppress the vibration without using state feedback in hovering situation. Furthermore, we will demonstrate a technique designing control parameters and verify the effectiveness by experiments.

en: Transactions of The Japan Society of Mechanical Engineers, Series C

ja: 日本機械学会論文集(C編)


en: Relationship Between In-Plane Stress and Modal Shape of Disk

ja: 円板の面内応力と振動モード形状に関する研究

en: In this paper, we analytically considered the effects of the in-plane stress of the disk on the changes of modal shape. The purpose of this study is to confirm whether the modal shape changes according to the in-plane stress. The results make it clear that the in-plane stress changes the modal shape and its curvature. The curvature of the modal shape is proportional to the reciprocal number of the bending stiffness. Thus, it is confirmed that the in-plane stress serves to change the bending stiffness distributions on the disk. Moreover, the natural frequencies of the disk are evaluated by two energy methods in which the variations of modal shapes are considered or not. The difference in the natural frequencies from two energy methods shows the effect of the changes in the modal shape of the disk due to the small difference in the results of the energy methods (maximum difference of strain energy: 7.1%). Finally, the two energy methods are compared to investigate the effects on the natural frequencies with hammering test. The experimental results show the traditional energy method is allowed to evaluate the natural frequencies practically.

ja: 日本機械学会論文集(C編)


en: A Study on the Transverse Vibration of the High Speed Rotating Circular Saw and the Countermeasure

ja: 高速回転する丸鋸の振動とその対策に関する研究

en: In this paper, we considered a new tensioning method by the centrifugal stress on the base metal of rotating circular saw. First, the residual stress distribution on the base metal generated by roll tensioning and the centrifugal stress distribution was compared by calculation using a disk model (Φ305mm). As the results, it was confirmed that the tangential stress ςϑR by centrifugal force at outer of disk became larger than the residual stress ςϑP by roll tensioning when the rotational speed is higher than 7300 rpm. This rotational speed is larger than 1.4 times of the critical speed (resonance rotational speed) of disk. And it is concerned that the unstable vibration may be generated. Therefore, we investigated the behavior of the unstable vibration and established the countermeasure by the rotating experiment. As the results of the rotating experiment, we considered that the unstable vibration is the self-excited vibration as the negative damping caused by the effects of the high-speed airflow around the rotating disk. According to this consideration, we investigated the relationship of the damping coefficient of disk and the behavior of the unstable vibration. As the result, it is confirmed that the rotational speed of the unstable vibration occurred becomes higher with the increase of the damping coefficient of disk. It is confirmed that it is possible to suppress the unstable vibration of disk and provide the tensioning effect by centrifugal force of disk.

ja: 日本機械学会論文集(C編)


en: An Approach to Creativity Education for Junior High School Students

ja: 中学生を対象とした創造教育の取組み

en: 徳島市を中心に近郊の中学生を対象としたレゴマインドストームを使用した創造教育に関する事業を科学研究費の補助を受けて行った．本論文は，その取り組みのまとめと今後の課題についてまとめたものである．行事を行ったのが休日でもあり，参加した中学生は科学技術に興味を持っていることがわかった．内容の理解も迅速であり，将来工学系学科に進学して頂けることを期待する．継続が困難な点が問題点としてあげられた．事業の内容から休日に行う必要があること，予算の面から指導する人員については，ボランティアに頼らざるえないことである．これらについてまとめた論文である．

en: Journal of Japanese Society for Engineering Education

ja: 工学教育


en: An Active Suspension System of One-wheel Car Models Using Fuzzy Reasoning

ja: 1車輪モデルに対するファジィ推論を用いたアクティブサスペンションに関する研究

en: This paper is concerned with the design of an active suspension system for one-wheel car models using fuzzy reasoning. The proposed active control for the suspension is derived as a linear combination of the defuzzificated values of the outputs in single input rule modules. The model is approximately described as a two-degrees nonlinear system subject to a random input. The experimental result shows that the proposed active suspension system more improves the vibration response of the vehicle body than a skyhook damper suspension system.

ja: 1/4乗用車モデルに対する単一入力ルール群(SIRMs)ファジィ推論によるアクティブサスペンション構築に関する研究である．従来のファジィ推論に比較して高速化を計りさらなる実用性の向上すめざすものである．本研究では，SIRMsファジィ推論の改良を行った．すなわち，動的重視度の導入により制御入力における重視度を変更してゆくことができるため，重視すべきサスペンション性能の重みの切替ができるためより効果的な制御器の構築ができる．

ja: 日本機械学会論文集(C編)