Human systems integration domain trade-offs in optimized manning: the task effectiveness scheduling tool

Abstract

The Sleep, Activity, Fatigue, and Task Effectiveness (SAFTE) model is a biomathematical model that uses information about sleep history, duration of wakefulness, and circadian phase to forecast an individual's future task effectiveness. It has seen practical application in the Defense Department within the Fatigue Avoidance Scheduling Tool (FAST). At present, given a personnel duty schedule with work and sleep periods, it is possible to obtain future predicted task effectiveness using FAST. It is not possible, however, to directly address the inverse question: given a task effectiveness threshold, what is the optimal schedule in terms of the time of sleep-wake periods and the assignment of performance sensitive duties? Such questions can now be addressed by importing data generated from FAST simulations into the Task Effectiveness Scheduling Tool (TEST). TEST is a mixed integer program that assigns persons to wake-sleep cycles and variable duty periods to provide coverage of a system function using the minimum quantity of personnel, while simultaneously ensuring individuals exceed a specified task effectiveness criterion during duty periods. The program then ensures that the temporal scheduling of duty periods maximizes averaged predicted task effectiveness over a 24-hour period. Accordingly, TEST allows analysts to mathematically determine optimal staffing and shift scheduling solutions via a deterministic model.