ISSC Conference

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Relating Head Measurements to Fit and Comfort of
Helmets

• Chuck Rogers, David Rogers, Duco Noordzij
• Artisent, Inc. Boston, MA, U.S.A.

2
U.S. Army Project Future Force Warrior (FFW)
Lead Technology Integrator (LTI) Eagle
Enterprise, A General Dynamics Company
3
New Capabilities

• Head-mounted-display
• Multi-spectral sensors for enhanced vision
• Communications support
• Eye and ear protection

4
Tough Constraints

• Similar or better ballistic protection
• Improved impact protection
• More stable retention system as platform for the
  sensors and displays
• Strict weight restrictions
• Accommodating wide range of head sizes and shapes

5
Popular Adult Sizing Schemes
All Male
5-95
Biking
Motor Cycling
Hockey
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ANSUR 88 Male Working Data (N 1774)

• Circumference 51.4 62.7 cm
• Width 128 173 mm
• Length 173 220 mm
• Initial request 5-95
• Two sizes 55-58 59-62
• Three sizes 54-57 57-60 60-63

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Two vs Three Sizes
3-sizes
2-sizes
Biking
Motor Cycling
Hockey
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Fit Models of 2 vs 3 Sizes
9
User Jury Feedback (N13)
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Decision

• Three sizes
• cover 5-99 percentile males
• Avoid need for extra-large
• Addition of extra small will cover females with
  total of 4 helmets

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Preferred Lacrosse Helmet (N80)
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Sizing by Circumference

• Measured Circumference predicted preferred helmet
  size correctly only 67.5 of the time.
• Why?

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Typical view of Head Sizing
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Medium Circum. 56.6 59.5 cm
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ANSUR 88 Male Working Data N 1774

• Correlations
• Width vs. Length 0.12
• Width vs. Circum. 0.54
• Length vs. Circum. 0.82
• Circum vs LengthWidth 0.93

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Ft Benning study (N 74)
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Small Helmet - Preferred
18
190
Medium Helmet - Preferred
180
170
Thk - Ln
160
Width
Thin - Ln
150
140
130
180
190
200
210
220
230
240
Length
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by Length and Width measurements
Predicting Helmet Size
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Preferred Delta (Length)
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Preferred Delta (Width)
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Assumptions about Shape
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Shape Discrepancy (N74)
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Predicting Helmet Size
by Shape Discrepancy calculations
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Small Helmet Preferred
26
Medium Helmet Preferred
27
Large Helmet Preferred
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Shape Discrepancy
applied to new sizes (N126)
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Shape Discrepancy
Predictions for new sizes (N126)
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Actual Predicted Distribution
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Three sizes for ANSUR 88 data
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Distribution of ANSUR 88 Population
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Spread sizes by 4.0 cm
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Percentage Wearing Each Size
Spacing Between Sizes (cm)
35
Preferred Delta (Length)
36
Estimation of Good / Poor Fit
Population Poor Fit Sum of All (Gap)2
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Sum Sq Fit Errors
Spacing Between Sizes (cm)
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Fit Scores all helmets
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Summary

• Circumference is not a good indicator of helmet
  size
• Shape discrepancy calculation improves
  predictions
• The extent of accommodation of head shapes is
  dependent on helmet shape, retention system, and
  liner materials
• All of these must be considered when determining
  helmet sizing scheme

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AcknowledgementsTechnology Program Office
(TPO)Natick Soldier Center
Matt Corea Brian Corner Dave Krasnecky Joe
Patterson Gilles Pageau
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Acknowledgements
Integrated Headgear Team

• Natick Soldier Center, Dave Krasnecky co-lead
• Kaiser Electro-Optics, Jim Melzer co-lead
• Artisent, Inc.
• DRS Optronics
• MSA, Mine Safety Appliances

Sources for soldier data

• Col. Bossi, Ft. Benning
• John Downey, Denny Langford, Camp MacKall
• Pierre Meunier, DRDC Toronto

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Presenter Contact Information
Chuck Rogers Artisent, Inc. 374 Congress Street
Boston, MA 02210 tel [phone] ext 204
fax [phone] email chuck_at_artisent.com