user centered approach to designing an ergonomics backpack for student aged 7-9

researches explore that the backpacks are the most proper tool for carrying daily school equipment, because it can asymmetrically distribute the load. in the present circumstances, more than 80 percent of primary school students in iran use backpack to carry their books and other means. school age children are in a critical musculoskeletal developmental stage, so using non-ergonomic backpack will result in serious physical injuries. carrying heavy backpacks could cause a wide spectrum of pain related musculoskeletal disorders and postural dysfunctions. weight is a controversial feature in backpack design. based on investigations, the value of 10% to 15% body weight is a justified weight limit for backpacks. while a statistical assessment in iran shows 57 percents of students carry backpack with more than 15 percents of their body weight. in spite of the fact that there are many studies about weight limitation and ergonomics features of backpack, just a few studies focused on designing backpack based on ergonomics features. user centered design has proven its efficiency to produce high efficient products which have the most adaptation with consumer demands. in this research, based on ucd approach, an initial backpack was designed after the recognition of students’ requirements and wishes, and then a prototype was manufactured. it was tried by considerable number of elementary students from difference point of view such as form, ergonomics and load sense. standard data acquisition methods were conducted like post-experience interview, assessing cognitive workload and thinking aloud. based on the results of evaluations, changes were conducted in the initial backpack and final school backpack was designed. final concept was named ucd backpack. results of functional evaluation showed that girls’ satisfaction of backpack dimension were more than boys. so with keeping ergonomics features, the dimension of backpack became larger. results also revealed the low rate of recognition of backpack’s performance in both girls and boys. so, the backpack must be simpler for use. according to behavior of students the inner shelves were eliminated due to complexity and the largest part of new backpack was placed in near the back with a zipper on top side. results also showed that children have problems to finding shoulders straps. so shoulders straps of previous location were shifted to middle of the backpack, in front of heaviest and biggest part. ucd backpack is designed in division parts. division parts are distributed loads better. in addition, they are caused to close the backpack’s center of gravity with the body’s center of gravity. these are important factors in reducing the effective load on shoulders, waist and neck. results of this study showed that getting information from children with methods such as interviews, questionnaire and poll, have poor compliance with the reality and the results sometimes may mislead designers thus it is advised to use scientific method such as data capture, hidden video recording and psychology. as a conclusion, ucd is very effective approach to designing the user centered design approach is the most effective method to designing products for children.