ABSTRACT
Objective To design a VDT operation related upper extremities fatigue detection system using keying duration (KD)as an indicator of fatigue and to execute experimental verification.Methods The system included the software part able to calculate,compare and analyze KD and hardware part able to support normal VDT operations.Subjects finished typing task under controlled condition while the system was running. The flexor digitorum superficialis (FDS), extensor digitorum communis(EDC),extensor carpi radialis(ECR),extensor carpi ulnaris(ECU)muscle fatigue were retrieved by sEMG method and standardized questionnaire. Results As the number of keystrokes increased, KD shortened by 1.3%, FDS MVC% dropped by 22.9%,and EDC MVC% decreased by 47.9%.The perceived level of typing fatigue also increased.Conclusion Results revealed KD's change with fatigue,showing the possibility of using KD as an indicator of fatigue and validating the feasibility and effectiveness of the system design.