The effect of holding methods on a baseball bat performance estimation system

Abstract

To obtain a value for the coefficient of restitution or of the trampoline effect for a given baseball bat it is typical to hold the bat in a clamping fixture or robot during simulated hits. This fixture and the structure or mechanism that connects the bat to earth form a dynamic system in which the bat is only one part. If we wish to measure some property of the bat alone, therefore, it is important to understand the influence of the clamp method and boundary conditions it imposes. To investigate this matter we have developed an evaluation system for the coefficient of restitution. Bats were held in three different ways while standard baseballs were fired at them using a pitching machine. In this paper we will describe the evaluation method and give examples of the results obtained on some metal bats. We conclude that the fixing method does affect the measured value of the coefficient of restitution, indicating that caution is needed when comparing the results from different test fixtures. © 2006 Springer-Verlag New York.