Dynamic strength based dryland weeders-ergonomic and performance evaluation

Human labour is a single costliest input in farming operations. Most of agricultural equipment designers regarded the operator as only another part of man-machine system and neglected their comfortness. Manually operated weeders are of push/pull type weeders, operated by application of force in dynamic motion. But, the existing dryland weeders designed based on static force exertion, even though they are in dynamic nature and require higher amount of force application than static ones. Hence, weeders of straight blade (apex angle 180°) and V blade (apex angle 90°) were developed for dryland conditions based on the dynamic strength optimized under laboratory conditions. The ergonomical and field performance evaluation was conducted for developed weeders along with one existing twin wheel hoe. The developed weeders showed an increased field performance in terms of field capacity, weeding efficiency and performance index with minimum physiological responses over twin wheel hoe. There was an increase in weeding efficiency, field capacity and performance index by 5, 21 and 7 percent and 4, 21 and 6 percent for straight and V blade weeders, respectively over twin wheel hoe. Further, the physiological responses such as heart rate, oxygen consumption, energy expenditure, acceptable work load (AWL), limit of continuous performance (LCP), overall discomfort rating (ODR) and body part discomfort score (BPDS) were reduced by 5, 7, 8, 8, 9, 11 and 6 percent for straight blade and 5, 7, 8, 9, 10, 13 and 10 percent for V blade respectively over twin wheel hoe.