ソフトボール用ウィンドミル式ピッチングマシンの試作研究

抄録

Softball is different from baseball in that the pitcher throws a ball with an underhand motion. Almost all softball pitchers throw a ball with a windmill pitching method (the arm one revolution as well as a windmill rotation). The windmill pitching method is different from the baseball pitcher throwing, so batters have a difficult time hitting the ball. For this reason, a softball pitching machine which can perform repetitive exercises for batting is required. However, currently, there are few machines capable of throwing with the windmill method on the market. In this study, we focused attention on the arm type and aimed to create a prototype pitching machine realizing a real pitcher’s windmill pitching method. We will add a ball gripping mechanism to the pitching arm of a commercially available arm type pitching machine. Based on the experiment results, the prototype machine had a maximum ball speed of 77 km/h. Also, the throwing position (pitching accuracy) of this machine was 460 mm in the vertical direction and 50 mm in the horizontal direction, so the tolerance in the vertical direction became large. The prototype machine is able to pitch fastballs and curveballs. It was found that the prototype machine can be controlled the spin rate by changing the length of the hand. In addition, there is a possibility that the eccentricity of the spin axis reduce from the simulation results. The prototype machine had the necessary throwing performance for junior high school student level softball practice. Key Words : Softball, Pitching machine, Windmill-type, Arm type, Curveball, Spin rate