上肢點擊運動之績效包括動作方向、移動距離與目標寬度等因素,過去Fitts’ Law是探討移動距離與目標寬度組成之難度指數對於動作時間存在之線性關係,而對於動作方向及其上肢肌電活動之研究未見相關探討。 本實驗利用生理訊號量測系統及動作時間測定儀,收集12位年輕與12位老年受測者(男女均各半)執行連續點擊作業時,其慣用手上肢肌群肌電訊號(Electromyography, EMG)、反應時間、動作時間及點擊失誤率等資料。實驗因子包括5種動作方向(0、45、90、135及180度)、3種移動距離(15、30及45公分)及2種目標寬度(1及2公分)。結果顯示,動作方向對於實驗中三條特定肌群(上斜方肌、前三角肌、肱橈肌)呈現顯著影響,當動作方向的角度增加,其肌電訊號也隨之增加。移動距離與目標寬度對於動作時間呈現顯著影響,隨著移動距離增加或目標寬度縮小,動作時間也隨之增加。當從事本研究上肢點擊運動時,其動作方向應與慣用手同方向,且應縮短移動距離及放大目標寬度為原則。
Three main ergonomics factors to affect the upper limb pointing movement performance are movement direction, movement distance and target width. In the past, Fitts’ Law have been emphasized on the difficulty index consisting of movement distance and target width with the linear relationship of movement time. Few studies on the movement direction affecting pointing performance were discussed in the literature. In this study, an experiment was conducted to collect electromyographic data, reaction time, movement time and pointing errors in the laboratory when a pointing task was performed using EMG and movement time measurement system. Twelve young and twelve elderly subjects (evenly divided between male and female) were recruited. Thirty experimental task patterns, consisting of five movement directions (0, 45, 90, 135, and 180 degree), three movement distances (15, 30, and 45 cm), and two target widths (1 and 2 cm) were designed and performed in this study.The study results revealed that movement direction significantly affected upper trapezius, anterior deltoid, and brachioradialis EMG behaviors. The %MVC (maximal voluntary contraction) of these muscles increased when the movement direction became larger. The movement distance and target width had significant influence on the movement time. The movement time became larger when the movement distance increased or target width decreased. The movement direction should be taken along with the same handedness direction when an upper limb pointing task is performed. Additionally, shorter movement distance and larger taget width showed be considered to increase pointing performance.