抄録
Knowledge of forces and moments applied to a baseball bat is important for a number of applications in training and analysis of biomechanics. The purpose of this study was to develop an instrumented grip handle designed to simultaneously measure the forces and moments exerted by both hands on a grip handle connected to a bat during baseball swing motion. The grip handle is designed to functionally equivalent to standard grip handles of baseball bats. Twelve pairs of strain gages were attached on the surface of an aluminum alloy bar inserted under the grip handle parts, such as knob-side and barrel-side grip parts. The bar is connected to the barrel side of cut bat with a connector so as to be able to connect to various types of bat, such as baseball bat and soflball bat. Strain signals were transmitted via a cable tethered to the batter's knob-side arm from the knob-end of the grip handle to twelve dynamics strain amplifiers. The output of the sensors was converted into the values of forces and moments exerted by each hand by resolving the static equilibrium equations. From calibration procedure, the sensor output voltages showed good linearity with respect to the applied loads, but cross-talking occurred between the longitudinal axial forces and the applied bending moments measured at the sensing points. Therefore, the interferences terms were approximated by using polynomial functions to reduce the interferences.
