緒論：慣性感測器 (Inertial Measurement Unit, IMU) 已被廣泛安裝於球棒尾部，用以測量棒球打擊者揮棒的運動學參數。然而，將 IMU 固定於棒尾可能使打者在握持長棒時感到不適。目的： 將IMU 固定於右打者前導手手背處，並開發揮棒運動學參數之演算法，旨在獲取打者在揮擊期的三軸合加速度、最大揮棒速度、揮擊期時間、最大揮棒速度時間差與擊中球瞬間之球棒進攻、垂直、水平角度；分析IMU與動作捕捉系統的信效度，並評估IMU所計算揮棒參數應用在不同層級打擊者的鑑別度。方法：大專公開一級組與一般組選手各 20 位參與本次研究，所有受試者之打擊習慣皆為右打者，每位受試者進行20次靜置於打擊座的球擊打實驗。同時使用 IMU 與動作捕捉系統收取數據並分析儀器之間的信效度；並檢驗IMU測得的揮棒速度和球棒角度的誤差值是否分別不超過 ±1.5 m/s 和 ±3°。結果: 兩組選手在兩種儀器下的揮擊期揮棒參數顯示出顯著的正相關 (mean r = .908)，且組內相關係數 (ICC) 顯示較高的一致性 (mean ICC = .861)；然而，在擊球瞬間，球棒的進攻角度、垂直角度和水平角度僅為中度相關 (mean r = .639)。此外，兩組層級打者的所有揮棒運動學參數均顯示系統性偏差 (p < .001)。在整體打擊者的揮棒參數結果中，只有揮棒速度 (+1.4 m/s) 和球棒進攻角度 (-3.0 deg) 位於預設目標範圍內，其餘參數均超出了預期範圍。結論：整體揮棒速度和進攻角度的測量結果位於設定之誤差值範圍內，但其他球棒角度皆超出了誤差值範圍，顯示慣性感測器在測量揮棒速度與進攻角度方面具有可靠性，但仍需進一步分析其他球棒角度測量中的誤差來源。

Introduction: Inertial measurement units (IMUs) have been widely mounted on the knob of baseball bats to measure the kinematic parameters of a batter’s swing. However, attaching an IMU to the bat knob may cause discomfort when gripping a long bat. Objective: This study aims to develop an algorithm for extracting swing kinematic parameters by affixing an IMU to the dorsal side of the lead hand of right-handed batters. Specifically, it seeks to measure the three-axis resultant acceleration, peak bat speed, swing duration, time to peak bat speed, and bat attack, vertical, and horizontal angles at ball impact. Additionally, the study examines the reliability and validity of IMU-based measurements compared to a motion capture system and evaluates the discriminative ability of IMU-derived swing parameters among batters of different skill levels. Methods: A total of 40 collegiate baseball players, including 20 participants from the top division and 20 from the general division, were recruited for this study. All participants were right-handed batters and performed 20 trials of stationary tee batting. Data were collected simultaneously using both the IMU and the motion capture system to analyze the reliability and validity of the instruments. The accuracy of IMU-derived swing speed and bat angles was assessed based on predefined error thresholds of ±1.5 m/s and ±3°, respectively. Results: The swing parameters for both groups of players showed a significant positive correlation under both instruments (mean r = .908), with good intra-class correlation coefficient (ICC) stability (mean ICC = .861). However, the bat attack angle, vertical angle, and horizontal angle at the moment of impact showed only moderate correlation (mean r = .639). All swing kinematic parameters across the two skill level groups exhibited systematic bias (p < .001). Among the swing parameters for both groups, only the swing speed (+1.4 m/s) and bat attack angle (-3.0°) were within the target range, while the remaining parameters exceeded the set targets. Conclusion: The IMU demonstrated reliable measurements for swing speed and attack angle within the predefined error thresholds. However, the bat angles at impact exceeded the acceptable error margins, suggesting the need for further analysis to identify potential sources of measurement errors in bat angle estimation.

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