그립감 향상을 위한 인간공학적 차량 Moving Handle 설계 및 평가 방법

Abstract

A Vehicle Moving Handle used for opening car door is important in terms of grip comfort. Grip comfort of Moving Handle can be improved by design dimension optimization. Previous studies evaluated applied forces, pressures, electromyograms (EMGs), and satisfactions to recognize optimal handle design dimension for muscle load reduce, work efficiency and customer satisfaction improvement. But proposed handle design dimensions based on cylindrical handle cannot be applied to complicated shape of moving handle design. And previous studies measured only objective measures like force, pressure, EMG and overall satisfaction, so that detailed grip comfort on Moving Handle use was not analyzed enough. The present study is intended to choose important moving handle design dimensions for grip comfort and analyze optimal size of each design dimension by grip comfort evaluation. The proposed study consists of five steps: (1) understanding design characteristics through design analysis and benchmarking, (2) major design dimension selection and develop experimental design based on Taguchi method, (3) ergonomic moving handle evaluation protocol establishment, (4) develop optimal moving handle design and validation. First, in design characteristics analysis step, 12 design dimensions of length, angle, and curvature was defined using 8 reference points and 2 reference line with shape of top, front, right, and cross section view. The size and range of each design dimensions was analyzed by benchmarking of 5 vehicles moving handles. Second, handle height, handle width, and handle side angle, grip part central curvature, inner-upper curvature, inner-middle curvature, inner-lower curvature was selected as major evaluation target design dimensions by the evaluation of design dimension priority according to grip posture and grip area change inducement. To recognize preferred size of selected design dimensions, grip comfort evaluation experiment by mixed-level of Taguchi Design L18 (21  36) was performed. Third, 20 participants (male: 10, female: 10) with various hand length and width was recruited and grip comfort of developed moving handle was relatively evaluated with specified evaluation measures (easy to control, fitness, length, angle, curvature of propriety, pressure distribution suitability, overall satisfaction) and 11-point bipolar scale (-5: very unpleasant, 0: no difference, 5: very pleasant) compared to reference moving handle. Handle height and width was significant design dimension to grip comfort. Handle height was preferred as 12.5% at minimum value (26.0 mm, p < 0.05) compare to maximum value within the design factor levels, and handle width was preferred as 11.0% at maximum (22.0 mm, p < 0.05) value compare to minimum value within the design factor levels. Handle side angle was preferred at maximum value (76.4), inner-middle curvature was preferred at maximum value (40.0 mm), and grip part central curvature was preferred at mean value (583.9 mm) without significance. Lastly, optimal moving handle was developed by considering sensitivity and preferred trend of design dimensions and optimization effect was validated. The sensitivity of moving handle design dimensions was analyzed as following order in terms of overall satisfaction: handle width (3.9), handle height (3.5), handle side angle (2.0), inner-upper curvature (1.0), inner-middle curvature (0.8), inner-lower curvature (0.4), grip part central curvature (0.4). The grip comfort of suggested evaluation best ODH and estimation best ODH was 24% ~ 48% higher than reference ODH, so that optimal moving handle design effect was validated. The moving handle design and evaluation method proposed in this study can be applied for optimal handle design to improve grip comfort of grip able handle products.