Shigemichi Ohshima

Optimization of Torque in Pole Vaulting using Genetic Algorithm (P248)

Pole vaulting has progressed rapidly in terms of improved mechanical properties and better appearance by using poles made of flexible fiberglass material. Competitive pole vaulting requires specific characteristics that promote higher jumps. Analysis of the dynamics of pole vaulting basically requires a thorough consideration with the aim of having a high flexibility of the pole and all joint torque actions of the body. In this research, simulation analysis to optimize the joint torque was done by using Genetic Algorithm. The system consists of a combination of a flexible pole and several links (vaulter). In the present genetic algorithm, the joint torque of the vaulter was expressed in terms of trigonometric functions. The expression for the torque was given by the amplitude, angular frequency and phase of the model equation. The overall evaluation function was the height and the control parameters were the joint torque, vaulter’s speed, and pole stiffness. The result of the optimum torque with respect to time readily obtained from our genetic algorithm show similar trend with published results obtained by inverse dynamic analysis.

Analysis of Nonlinear Deformations in Japanese Bows (Application of Elastica Theory)

1. 緒 言 弓道は日本の武道,弓術を引き継ぐ形で今ではスポーツ 化しているが,他のスポーツと比較しても長い伝統を持っ ており,その射法も技術的な面ばかりでなく,精神的な面 も含まれたものになっている.したがって,「礼に始まり, 礼に終わる」という武道の精神がかなり重要なものとなっ ており,現在も多くの人々が弓道をたしなみ,その射法の 修得,研鑽に勤しんでいる.この弓道に使用される用具が 和弓である.和弓は,弓の中心を矢が通らない,構造的に アンバランスなものであり,その結果,矢の軸線と矢に生 じる力の向きが一致せず,そのままだと矢は右上のほうへ 飛ぶようになるなど,技術的にコントロールすることがか なり難しい用具である. 和弓は高い柔軟性を有する多くの竹材および木から構成 される複合材料である.基本的な構造は竹―木―竹の 3層 構造であり,縦に配置された「ひご」と呼ばれる芯材を数本 挟んで復元力を高めている.構成材料は一般に長さに沿っ て異なる曲率を有し, Fig.1に示すように,通常は対称では 和弓における非線形変形特性の解析 *(エラスチカ理論の適用)

Gaze Point Analysis in Movement Prediction of Soccer Players by Image Processing

This paper describes the effect of positioning the gaze point of a defensive player to predict the movement of an offensive player in a soccer game by using the recognition algorithm. In this research, positioning of the gaze point is systematically varied to predict the movement of the offensive player, target. Here, pattern images of the target moving to the right and left side (directional movement), and sweeping the left or right foot in front of the ball and moving to the right and left side (feint movements) are recorded by a digital camera. The stored feints movements are then matched with the directional movements to predict the direction of movement of the target. The matching System is developed by mimicking brain function for image recognition. Therefore, in using the matching System, we can analyze the gaze point as a System that is similar to the visual information exchange of the retina and brain. The optimum position of the gaze point is then evaluated based on the difference of the matching degree outcome in the opposite directions.

Analysis of Large Contact Deflection of Compressed Slender Rod with Low Support Stiffness.

Large deflection occurring in flexible materials is of both analytical and technological interest. This report deals with the postbuckling behavior of a slender rod. The spring-hinged slender rod is subjected to compressive forces at its clamped ends. With contact between the two different parts of the rod, several analytical formulae are derived in terms of elliptic integrals for arc length, deflection, distance between the two ends, curvature, bending moment and bending stress. Moreover, an experiment is carried out to confirm the applicability of the proposed theory. The experimental results agree well with the theoretical ones.

Fundamental Study on Large Deformations of Poles and Pole-Vaulting Characteristics

The record in pole-vaulting has been improved by using flexible fiberglass poles. In analysis of the dynamics of pole-vaulting, it is necessary to consider the high flexibility of poles. This paper deals with the large deformations of poles subjected to concentrated loads at two supporting points. A simple combination model is introduced which consists of a mass (vaulter) and a pole. Analytical solutions in terms of elliptic integrals are derived for vertical and horizontal displacements. Furthermore, time progress of pole deformation is investigated. From the results, it is clarified that the initial conditions(e.g., vertical and horizontal velocities of the vaulter) and the applied bending moment play important roles.