| 摘要 |
PURPOSE:To practice pitching alone with a simple device and also, to confirm the speed of a pitched ball by oneself, by detecting the impact force of the pitched ball for an iron plate supported by >=3 load cells. CONSTITUTION:>=3 load cells 2 are arranged and fitted between an iron plate 1 and 3. A ball is thrown to a ball receiving range 4 of the plate 3 and an output is obtained in accordance with its impact force from the load cell. An impact force F is shown F=alphamV(1+e)/t, where (m) is mass of the ball. A proportional coefficient alpha is constant and a contact time (t) and the force F are measured from the output of the load cell in said formula. The relation between the force F and a repulsion coefficient (e) is stored in an ROM because (e) depends on the speed of a pitched ball. In this way, the speed of a pitched ball V is computed from said parameter and the output of the load cell and its calculated value is displayed. |
