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Performance assessment of the suspended-load backpack

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Abstract

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.

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Abbreviations

A :

Oscillating load ratio (scaling factor)

c :

Equivalent pack damping coefficient

F osc :

Oscillating pack force

F Pack :

Total pack force

g :

Gravity

k :

Equivalent pack stiffness

X, Y:

Amplitude of oscillation of person and pack

m :

Total pack mass

S :

Stature (height) of person

t :

Time

v :

Walking speed

ω :

Walking frequency

ω n :

Natural frequency for the pack

δ :

Static deflection of pack

ϕ :

Phase angle

l 0 :

Leg length of person

\(x, {\dot{x}}, {\ddot{x}}\) :

Vertical position, velocity, and acceleration of the torso

\(y, {\dot{y}}, {\ddot{y}}\) :

Vertical position, velocity, and acceleration of the pack

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Authors and Affiliations

  1. Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, ON, M5S 3G8, Canada

    J. Hoover & S. A. Meguid

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  1. J. Hoover
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  2. S. A. Meguid
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Correspondence to J. Hoover.

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Hoover, J., Meguid, S.A. Performance assessment of the suspended-load backpack. Int J Mech Mater Des 7, 111–121 (2011). https://doi.org/10.1007/s10999-011-9153-7

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  • DOI: https://doi.org/10.1007/s10999-011-9153-7

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