Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

First Advisor

Justin E. Seipel

Committee Chair

Justin E. Seipel

Committee Member 1

John M. Starkey

Committee Member 2

Charles M. Krousgrill

Abstract

Walking or running while carrying loads has always been a tedious task, more so when the loads are heavy. Such a task of carrying loads not only requires extra effort but also leads to physical pain and in some cases injury. Prior studies on human locomotion with a suspended load have used models that are restricted in their DOFs and so are not able to take into account the fore aft movement in human beings. The objective of this thesis is to model the dynamics of sagittal plane center-of-mass locomotion with a suspended load and apply findings to carrying loads with an elastic pole.

The approach taken was to develop and analyze a variant of the Hip Actuated Spring-Loaded Inverted Pendulum (SLIP) model of locomotion that has a second sprung mass added to represent a suspended load. This model showed a large increment in human running speed and stride frequency as the suspension stiffness was increased. A stability analysis on the model showed branching among fixed points with one branch nearly stable while the other branch has greater stability. This particular model was able to show a reduction in peak forces and amplitude of the load for very compliant suspensions.

In order to limit velocity change that occurs with changing suspension stiffness, a variable torque model was developed. This model was able to limit the velocity magnitude and stride frequency near target values. It also showed reduction in peak shoulder forces and has better stability.

One direct application of this work is to inform and potentially influence better practices involving the ancient human behavior of carrying heavy loads with bamboo poles, which remains common in some regions of Asia. The dynamic aspects of the hip actuated SLIP were synthesized with those of the beam bending model to design a compliant pole. Optimizing the design parameters of bamboo helped us to obtain a region which provided suitable reduction in peak shoulder forces within the safety limits of avoiding fracture.

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