Accuracy and Error Trends of Commercially Available Bat Swing Sensors in Baseball.

Yoshitaka Morishita,Tsutomu Jinji

doi:10.3390/sports10020021

Abstract

In baseball, the swing speed and swing angle of the bat just before ball impact are important to increase the speed and horizontal distance of a batted ball. This study investigated the accuracies and error trends of four commercially available bat sensors to measure these parameters. The hitting motions of seven healthy participants were measured simultaneously using the bat sensors and an optical motion capture system, and the swing speeds and swing angles were compared. The swing speed was measured with high accuracy, as indicated by the high intraclass correlation coefficient (ICC) between the bat sensor and the motion capture system measurements (mean ICC = 0.78). However, the ICC for the swing angle was lower (mean ICC = 0.58) than that of the swing speed for all but one bat sensor, indicating low accuracy. Moreover, in the high swing speed range, the accuracy of the swing speed tended to decrease for three bat sensors, but the trend of the swing angle was different among bat sensors. Significant systematic biases or proportional errors were found for all bat sensors, indicating the possibility of error correction. The sensor used in this study can help to evaluate the differences between players with different competition levels and hitting motions. Coaches need to be cautious in taking measurements of players with high swing speeds and in assessing slight changes within an individual.

Highlights

In recent years, inertial measurement unit (IMU) sensors have become smaller and more affordable; they are being used by competitors, coaches, and researchers [1]
Prior research has shown that the swing speed and swing angle just before ball impact, which can be measured through a sensor attached to the bat knob, are important factors in increasing the speed and distance of the batted ball [4,5]
This study investigates the trends of swing speed and swing angle errors for four commercially available sensors using an optical motion capture system as the gold standard method and examines the possibility of correcting the errors to verify the effective use of the bat swing sensor in practice at various levels of competition

Summary

Introduction

Inertial measurement unit (IMU) sensors have become smaller and more affordable; they are being used by competitors, coaches, and researchers [1]. In the case of hitting, wireless IMUs that can be attached to the knob of the bat have been developed [3], and several manufacturers have commercialized IMUs that measure the swing speed and trajectory (swing angle) of the bat. Prior research has shown that the swing speed and swing angle just before ball impact, which can be measured through a sensor attached to the bat knob, are important factors in increasing the speed and distance of the batted ball [4,5]. Studies have shown that the swing speed increases at higher levels of competition [8], and players measure these parameters using IMUs while they work toward improving their hitting skills

Objectives

Methods

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Conclusion