Fatigue accumulation in the assignment of manual material handling activities to operators

In an industrial context it is not easy to evaluate how to assign activities to operators for reaching the improvement of the performance of the system, since the influence of the activities on the operators is strictly linked to their personal characteristics. Moreover, during the performance of the activity, the operators experience physical fatigue which can accumulate during time if they cannot recover properly. For manual material handling activities, the whole body is involved; subsequently, the physical fatigue can be measured through the energy expenditure rate. In relation to this, the aim of this paper is to improve the scheduling of manual material handling activities of the operators by knowing the energy expenditure rate and the duration of the activity and by knowing how the specific operator accumulates fatigue and recovers. The analysis carried on permits to consider more the influence of human factors in the scheduling of operators’ activities during the working day.