Evaluation of Ergonomic Design Based on Dynamic Model of Scissor

Unlike general scissors, many commercial hairdressing scissors reflect ergonomic design with handles that provide users with comfort, minimizing fatigue and the risk of injury. However, there has not been a lot of prior research on quantitatively evaluating the merits of ergonomic design. This paper proposes a quantitative criterion to evaluate the performance of commercial hairdressing scissors. An experiment was conducted using several hairdressing scissors to establish the quantitative evaluation criterion. It was discovered that more fingers were involved than required to create a scissoring, and these fingers exerted antagonistic forces during the scissoring. Incorporating this property, a dynamic model of scissor mechanics was developed to analyze the characteristics of redundant finger forces, and a corresponding load distribution algorithm was derived. Three different types of scissor designs were compared through simulation. It was observed that the more ergonomic design was applied to the scissor, the less rotational kinetic energy was consumed. As a result, we propose rotational kinetic energy consumption as the quantitative evaluation criterion. The results of this research will be useful in designing specific scissor designs.