Development and performance of a ball shooting machine

摘要

Wind tunnels are often used when investigating the aerodynamic characteristics of sports balls, and have proven to be effective experimental equipment. However, wind tunnel experiments are fundamentally targeted at testing fixed steady states, so in some cases ball ejection units capable of unsteady states are needed. This research undertook the design and development of an impact type ball ejection unit with stable initial parameters and striking characteristics that make variable-state testing of sports balls possible. The kick arm swings due to an actuator activated by air-pressure, impacting a fixed ball. The swing action itself has 1 degree of freedom; however, there are 3 degrees of freedom for the alignment of the striker. The soccer ball may achieve a maximum velocity of 131 km/h when ejected, allowing a shooting speed of 100 km/h when the unit is operating at 70% power. Further, it was found that there was a direct correlation between impact velocity and the initial velocity of the ball.