4Features. Structural Dimensions for U.S. Adults (1989). Figure 1. Static BodyFeatures. Structural Dimensions for U.S.Adults (1989).(see also Figure 2 andTables 1 to 4 for Values)[source: Kroemer, 1989]
5Figure 2. Percentile of Population Group Normal or GaussianData DistributionNo. ofSubjects5th percentile =5 % of subjectshave “dimension”below this value50 %95 %Dimension(e.g. height,weight, etc.)
8Table 3 - U.S. Adult Civilians (1989) SegmentGender5 th Percentile50 th Percentile95 th Percentile11. Buttock-to-Knee (sit)MF54.0 cm51.859.4 cm56.964.2 cm62.512. Thigh-to-Heel Height (sit)39.235.544.239.848.844.313. Chest Depth (stand)21.424.227.629.714. Elbow-to-Elbow (sit)35.031.541.738.450.649.115. Hip Width (sit)30.831.235.436.440.643.7See “Static Body Features” Figure 1 for measured dimension
9Table 4 - U.S. Adult Civilians (1989) SegmentGender5 th Percentile50 th Percentile95 th PercentileWeight (kg)MF56.2 kg46.274.0 kg61.197.1 kg89.9See “Static Body Features” Figure 1 for measured dimensionNote for Tables 1-4: Due to anatomical reasons, Male data islarger than Female data at all %iles, with the exception of#13 (Chest Depth) and #15 (Hip Width), which shows areversal of this trend.
10Body Segment Lengths [all values are in centimetres] Limb White Male White Female(Percentile)5 th50 th95 thUpper Arm28.630.432.326.127.829.5Forearm25.927.529.222.724.125.5Thigh40.4220.127.116.119.542.1Shank38.945.334.737.440.0LJoint or HingeSegment
11Body Segment Density Body Segment Year = 1860 Year = 1955 Head and Neck1.11 g/cm3Trunk--1.03Upper Arm1.081.07Forearm1.101.13Hand1.111.16Thigh1.05Lower Leg1.09FootDensity = Mass / VolumeHuman Segment Density ~ 1 g/cm3
12Main Segment as % of Total Body Weight Body Segment WeightsMain Segment as % of Total Body WeightIndividual Segment as% of Main SegmentHead and Neck = 8.4 %Head = 73.8 %Neck = 26.2 %Torso = 50 %Thorax (chest) = 43.8 %Lumbar = 29.4 %Pelvis = 26.8 %One Total Arm = 5.1 %Upper Arm = 54.9 %Forearm = 33.3 %Hand = 11.8 %One Total Leg = 15.7 %Thigh = 63.7 %Shank = 27.4 %Foot = 8.9 %
13Centre of Gravity Relative location of C-of-G’s on body segments. See the C-of-G%-iles in the nexttable [Dempster, 1955]
15Center of Gravity/Segment Length = L1/L2 (%) Year = 188919551969Total Body--41.2 %Head43.3 %46.6Arm47 %43.651.3Forearm42.14339Hand49.4Total Arm41.3Forearm & Hand47.2Thigh4443.3Calf (= Shank)4237.1Foot44.442.944.9Total LegCalf & Foot52.443.747.5C-of-G willnormally be closerto the “thicker”proximal endof the segment.L1L2Distal EndProximal End
16Center of Gravity/Segment Length = L1/L2 (%) C-of-G / SegmentLength0.500.5060.4300.4360.4330.500C-of-G willnormally be closerto the “thicker”proximal endof the segment.L1L2Distal EndProximal EndHead & NeckHandForearmUpper ArmThighLegFootTrunk[modified from Winter, 1992]
17Radius of Gyration/Segment Length = K/L (%) (Cadaver Experiments) Body SegmentFrom Proximal EndFrom Distal EndHead, Neck, Trunk49.7 %67.5 %Full Arm54.264.5Forearm52.6Hand58.757.7Forearm and Hand82.756.5Thigh5465.3Shank52.864.3Foot69Shank and Foot73.557.2KLDistal EndProximal End
18Example – Anthropometric Forearm Data PurposeBecome accustomed to Generating and Using Anthropometric Data tables and formulas.Steps (Use ruler or tape measure for length measurement)Measure length, L, of forearm (elbow to wrist) and diameter, d, about half way along lengthCalculate approx. forearm volume, V = (d/2)2LCalculate forearm mass, m, in two ways … (do they match?)using m = D x V and density from Density Tableusing “Body Segment Weights” tableCalculate forearm C-of-G using C-of-G/Length ratio tableCalculate forearm radius of gyration, K, using forearm length, L, and “Radius of Gyration” table
19Forearm Data Table Dimension Symbol Value (female) (male) Length L Closest %ile for Length%DiameterdVolumeVMass (from density formula, D = m/V)mMass (from “Body Segment Weight” table)C-of-G (from elbow)C-of-GRadius of Gyration(from elbow)K
20Ergonomic Design Principles Designing for the AverageThere is no “average” personVery difficult to find person who is average in more than a few dimensions (e.g. avg. height may not necessarily mean avg. leg length and arm length)Designing for the average can be an over-simplificationOnly to be done after careful evaluation (e.g. very specific subgroup)e.g. Clothing Study (n = 4096 people)Center 30% was taken as Avg. Percentile, BUT…Only 26% were of Avg. HeightOnly 7.4% had Avg. Chest CircumferenceOnly 3.5% had Avg. Sleeve LengthOnly 0.07% had Avg. Waist CircumferenceAnd 0% had Avg. Foot Length
21Designing for the Extremes PrincipleTry to accommodate entire population groupMaximum Levelse.g. doorways, size of escape hatches on military aircraft, strength of ladders and workbenchesMinimum Levelse.g. distance of control button from operator, force required to operate control lever or buttonPractical Design Rangeuse 5th and 95th percentiles of pop. group as extremesuse smallest female and largest maleQuestionsEffects on those excluded?Can we restrict users to a certain pop. group?
22Designing for Adjustment PrincipleTry to allow for adjustments in size, shape, position, intensity, and duration of the product, device, procedure, or system to accommodate unexpected circumstancesPractical Design RangeCommon to use 5th %ile female and 95th %ile maleResults in accommodation of 95% (not 90%) of 50/50 male/female pop. group because of overlap in male and female body dimensionsExamplesCar seats, desk height, footrests, office furnitureQuestionsUse: one shot vs. continual?Use: one user or shared?Ease of and Training for using “adjustments”?What happens if design range misused?
23Ergonomic Design Approach Determine important body dimensionsDefine population group (men, kids, Swedes?)Decide on which design principles will be used (design for extremes, average, adjustment?)Select which sub-group of pop. group will be designed for (5th, 50th, 73rd, %ile?)Extract values from Anthropometric TablesAdd dimensional allowances for any clothing, equipment, safety precautions, and task performance.Build “prototype” or “mock up” of product, device, procedure, or facility.Test prototype with human subjects.
24Sources Used Chaffin et al., Occupational Biomechanics, 1999. Dempster, Space Requirements of the Seated Operator, 1955.Hay and Reid, 1988.Kreighbaum & Barthels, Biomechanics: A Qualitative Approach for Studying Human Movement, 1996.Kroemer, “Engineering Anthropometry”, Ergonomics, 32(7): , 1989Sanders and McCormick, Human Factors in Engineering and Design, 1993.Moore and Andrews, Ergonomics for Mechanical Design, MECH 495 Course Notes, Queens Univ., Kingston, Canada, 1997.Oskaya & Nordin, Fundamentals of Biomechanics, 1991.Winter, Biomechanics of Human Movement, 1992.