Study on functional relationships between ergonomics indexes of manual performance

This paper investigates functional relationships between some of the key ergonomics indexes in manual performance, and attempts to condense the ergonomics appraisal indexes system and thus evaluate hand performance wearing EVA (extravehicular activity) glove, design and improve EVA glove's performance. Four types of ergonomics indexes were studied, i.e., dexterity, tactile sensibility (TS), strength and fatigue. Two test items of insert sticks into a holes-board (ISIHB) and nuts-bolts assembly task (NBAT) were used to measure dexterity, while shape discrimination (SD) was employed for TS, and grip force (GF) for strength and fatigue. The variables measured in this investigation included accomplishing time (AT) of ISIHB and NBAT, correct rate (CR) of SD, maximal grip force (MGF), instant grip force (IGF) and endurance time of grip force (ET_GF). Experiments were conducted on 31 undergraduates (eight female and 23 male) with two experiment conditions of bare-hand group and gloved hand group. Results demonstrated that dexterity and TS performance of gloved hand group declined significantly compared with those of bare-hand group (p < 0.001). There were not significant differences in strength and fatigue between two conditions (p > 0.05). Four effective functional relationships were developed between four pairs of ergonomics indexes in bare-hand group. In gloved hand group, in addition to above-mentioned four pairs of relationships, another formula was found, which was over(y, ^) = 0.02061 + 0.01233 x (p < 0.01, dexterity and TS).