Your question is a little ambiguous and does not make it clear what type of fatigue you are referring to...
Depending on whether you are interested in 'metal' fatigue or 'mental' fatigue I can answer this question. There are a range of software products for looking at the link between the timing of work and rest and fatigue. The most widely used product commercially is FAID (google this with fatigue for demo copies). In addition, the US military have a more focused package for 'mission planning'. The general models predict the likely level of mental fatigue based on the timing and duration of the work period. Workload within the work period is typically accounted for by raising or lowering the acceptable fatigue threshold based on a U-shaped Yerkes-Dodson relationship between arousal and performance. There is a recent review article on this topic
DOI: 10.1016/j.aap.2009.12.030
On the other hand if it is 'metal fatigue' you may need someone with more engineering and calculus...
Thank you for your response. I am looking for a system approach for all factors contributing to fatigue for heavy loaded operators working in a hot environment, so I think your hints will give me nice clues to track.
We had built up kinetographic approach especially for estimation of work load and fatigue in operators. This tool is in special armchair so we can measure change of human functional state in sitting position. We used it in patients and in participants of laboratory market. You can see pyblications on my page
Hello, take a look at wrist-worn raw data actigraphy for sports research and clinical trials. Find out how these accelerometers can benefit your project.