A reverse design method to improve comfort of electric tools in closed-loop evaluation system

A method is offered to avoid the musculoskeletal disorders (MSDs) caused by electric tools and improve overall comfort. According to the method, The electric tool grips are designed according to the pressed human surfaces. The grips are replaced by clay models first. When holding the models, human body surfaces are deformed and recorded by clay surfaces. Simplify and rebuild the surfaces. Rapid prototyping method is adopted to make new grips for electric tools according to the simplified surfaces. The experimenters are informed to manipulate the electric tools again and conduct questionnaires to rate overall comfort. The result of the questionnaire is analyzed to see whether comfort of the surfaces have been improved. If it is significantly improved, utilized the work loading and the control point number as references to redesign the grip surfaces in the same way again. So, the closed-loop system is established, it will not stop improving comfort until no significant improvement could be found. The results are shown in a flow chart. It is proved by assessment scores that, the method can be applied to redesign the electric tools to which soft tissue-related ergonomic factors are particularly important.