There were two main aims to the thesis: (1) to develop a mobile 'in-field' pressure
measurement system to assess pressure at Body-Load Carriage System (LCS)
interfaces (shoulders and hips). (2) To evaluate and compare prototype LCS
designs in-field and to provide human factor requirements for design improvement. To satisfy the aims of the thesis in-field trials were carried out in a realistic military context. The purposes of these trials were to: (1) compare the standard issue British military LCS against a prototype LCS design in terms of pressure and subjective comfort; (2) increase the understanding of the properties of the shoulder and hip interfaces; (3) assess the relationship between loading at
the shoulder and hip; and (4) identify whether other ergonomic issues are also
important to consider. By assessing these areas human factors requirements for
design were then determined. An additional (minor) aim was to develop a new
prototype LCS with a greater degree of compatibility between the components of
a military LCS (backpack and webbing), incorporation of material advances, and
with a greater consideration for fit and posture.
Four main experimental trials were performed the first (n = 11) assessedth e affect
of clothing layers at the body-LCS interface on transmitted pressure. Results
showed that clothing layers even worn in multiple have no effect on pressure
transmission. Thus, no relief from pressure exists for the user. This highlighted the
importance of the materials in the shoulder and hip straps. The second trial (n =
10) was a laboratory based comparison of two backpacks, the first the standard
issue British military pack, the second a new prototype. Results found significant
difference in subjective comfort and also peak pressure at the shoulder interface.
The prototype backpack being associated with reduced peak pressure and
increased comfort. The third trial (n = 10) assessed whole LCSs (backpack +
webbing) in field with civilian participants. The standard issue LCS was compared
against a prototype LCS. No significant difference in pressure was identified
between the two LCSs, although differences in subjective comfort ratings were
still significant indicating a preference for the prototype LCS. The final trial (n =
30) was military in-field trial. Military personnel and loadings were utilised.
Again no significant difference in pressure data was identified although
differences in subjective ratings remained significant with the prototype LCS
design being preferred.
Research findings highlighted the continued need for subjective assessment. The
relationship between pressure loading at the shoulder and hip interfaces, along
with locations of peak pressure within each interface were found to be important
factors affecting comfort. Increased pressure distribution at the interfaces via new
materials and design was also associated with increased comfort. Other areas
which appeared important were the effect of posture and other physical forces not
measured (i.e. shear and friction). Human factors guidelines were created for
finiher LCS designs and future research ideas were presented.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.