ローラ式ピッチングマシンの投球精度に関する研究 : ボール縫い目とローラの検討(機械力学,計測,自動制御)

概要

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The most common commercial pitching machines for baseball are the "roller" type and the "arm" type. Pitches such as the fastball, curveball and screwball are easily achieved by the pitching machine with three rollers which were developed by the authors. In this study, the moving behavior and contact stress state of the ball pitched with the three rollers type pitching machine is analyzed using dynamic finite element analysis software (ANSYS/LS-DYNA). The effect of a seam of a baseball to the throw accuracy is analyzed numerically. In the analysis, the finite element models of a detailed baseball with a seam and a pitching machine with three rollers are used. Additionally, the initial velocity and the spin rate of the pitched ball are filmed using a high-speed videograph, and those pictures are compared with the finite element analysis. From the analytical results, it is understood that the coefficient of friction between the baseball and the rollers is not affected. Additionally, it is obvious that the ball's velocity and spin rate are relatively unaffected by the seam orientation, while the throw's horizontal and vertical angles are notably affected by the relative angular velocity of the rollers and the orientation of the seam.
2007-11-25