GruntSim is a biomechanics and physiology simulation tool for burden management that resulted from a five-year, $8.6 million project called Enhanced Technologies for Optimization of Warfighter Load (ETOWL), which was awarded to the Virtual Soldier Research program by the U.S. Navy. The purpose of the GruntSim project was to create simulation tools for the study of load carriage by military personnel.

For example, military commanders using GruntSim can conduct trade-off analyses of load carriage in terms of agility, survivability, human performance, and physiological assessments by programming Santos with specific height and weight data for each person, loading Santos with gear selected from a menu of some 160 items, and having Santos perform various warfighting scenarios. Depending upon the stress experienced for each task, Santos’s spine, knees, ankles, and other joints will flash green for low stress, yellow for moderate stress, or red for high stress.