Performance assessment of the suspended-load backpack

The suspended-load backpack is found to improve the energy efficiency of walking with a load in some scenarios. The objective of this study is to (i) analyze the dynamic load of the suspended-load backpack over a range of walking speeds and pack masses, and (ii) determine the optimal design parameters for the suspended-load backpack to minimize the effect of dynamic load on the efficiency of walking. A simple spring, damper and mass system is used to model the performance of the suspended-load backpack as well as the typical hiking pack. The oscillating load and phase angle are calculated over a range of loading and spring stiffness values to determine the system resonance and optimal spring stiffness design range for the suspended-load backpack. Our results reveal that the stiffness for the suspended-load backpack should be designed below one half of the resonance stiffness to minimize dynamic loads at a given walking speed. The location and magnitude of the maximum phase angle is also calculated. A performance comparison between the suspended-load backpack and a typical hiking pack demonstrates the beneficial range for the suspended-load backpack. The suspended-load backpack is found to provide significant reductions in the peak backpack load, compared with a typical hiking pack, while carrying large loads at fast walking speeds. The suspended-load backpack performs poorly for low pack loads due to in-phase oscillations between the pack and the walking person.