AnthropometryEngineering AnthropometrySelection vs. Job ModificationExclude as Few as PossibleExcluded PercentilePopulation DimensionsBody Position DescriptionsWrist/Hand MotionsSlide 9Slide 10Body DimensionsVariations in body dimensionsVariations in StrengthOther CharacteristicsAge of WorkforcePersonal SpaceStatistical CalculationsNormal DistributionDistribution CalculationsSlide 20AnthropometryAnthropometryInitiativeInitiativeImaginationImaginationNeedsNeedsDexterityDexterityIntelligenceIntelligenceAnd so forthAnd so forthVisual acuityVisual acuityDeterminationDeterminationUpper back Upper back strengthstrengthAgeAgeLeg lengthLeg lengthAnthroposAnthropos (human) + (human) + metreinmetrein (to measure) (to measure)The study of how people vary inThe study of how people vary inEngineering AnthropometryEngineering AnthropometryPhysical body size Physical body size –StaticStaticTwo dimensionalTwo dimensionalThree dimensionalThree dimensional–FunctionalFunctionalStrengthStrength – IsometricIsometric–Dynamic – isotonic, iso- Dynamic – isotonic, iso- kinetic, iso-inertial etc.kinetic, iso-inertial etc.–MVC joint torquesMVC joint torquesBiomechanical / inertial properties Biomechanical / inertial properties –Segment massSegment mass–Segment center of gravity locationsSegment center of gravity locations–Muscle attachment sites and lever armsMuscle attachment sites and lever arms–Failure stresses of ligaments, tendons, bones Failure stresses of ligaments, tendons, bones etc.etc.Selection vs. Job Selection vs. Job ModificationModificationTwo basic strategies:Two basic strategies:–Selection—fit the person to the job.Selection—fit the person to the job.–Job modification—fit the job to the Job modification—fit the job to the personpersonFollow the second strategy: the Follow the second strategy: the key to progress has been to key to progress has been to challenge the environment.challenge the environment.Exclude as Few as Exclude as Few as PossiblePossibleMinimizes the number of people Minimizes the number of people excluded, which tends to make excluded, which tends to make the job easier for everyonethe job easier for everyoneBalance seriousness of exclusion Balance seriousness of exclusion with cost of inclusionwith cost of inclusionExcluded PercentileExcluded PercentileMay be: May be: –Upper (a door tall people can’t fit under)Upper (a door tall people can’t fit under)–Lower (a task requiring manual dexterity)Lower (a task requiring manual dexterity)–Both (intelligence test for factory job)Both (intelligence test for factory job)Designing for the mean may exclude Designing for the mean may exclude half the population.half the population.Population DimensionsPopulation DimensionsDefine the user population.Define the user population.Consider the source of population Consider the source of population dimensionsdimensions–Male/femaleMale/female–Military/civilianMilitary/civilian–AgeAge–EthnicityEthnicity–OccupationOccupationBody Position Body Position DescriptionsDescriptionsPlanesPlanes–Saggital – divides the body into left and Saggital – divides the body into left and right half (medial/lateral)right half (medial/lateral)–Coronal – divides the body into front and Coronal – divides the body into front and back half (anterior/posterior)back half (anterior/posterior)–Transverse – divides the body into top and Transverse – divides the body into top and bottom half (superior/inferior)bottom half (superior/inferior)LimbsLimbs–Proximal: close to torsoProximal: close to torso–Distal: further from torsoDistal: further from torsoWrist/Hand MotionsWrist/Hand MotionsFlexion – closes the joint angle from neutral position.Flexion – closes the joint angle from neutral position.Extension – opens the joint angle from neutral position.Extension – opens the joint angle from neutral position.Adduction/ abduction – opens and closes laterallyAdduction/ abduction – opens and closes laterallyWrist/Hand MotionsWrist/Hand MotionsRadial deviation/ulnar deviationRadial deviation/ulnar deviationWrist/Hand MotionsWrist/Hand MotionsPronation/supinationPronation/supinationBody DimensionsBody DimensionsSample 95th percentile dimensions (cm) of nude U.S. adult civilians.Female MaleStature (height) 173.73 186.65Eye height 162.13 174.29Thigh height (sitting) 18.02 18.99Forward reach 79.67 86.70Hip breadth (sitting) 43.22 41.16Weight (kg) 84.8 99.3Variations in body Variations in body dimensionsdimensionsMost body dimensions do not correlate well Most body dimensions do not correlate well with stature, coefficient of determination Rwith stature, coefficient of determination R22 is less than 50%. So be careful when is less than 50%. So be careful when predicting other dimensions from stature.predicting other dimensions from stature.Individual segment weights are calculated Individual segment weights are calculated from total body weight.from total body weight.In absence of data female may be In absence of data female may be estimated as 93% of male if no data estimated as 93% of male if no data availableavailableVariations in StrengthVariations in StrengthFemales average 63% isometric strength of Females average 63% isometric strength of males.males.Strength of specific muscle groups varies Strength of specific muscle groups varies depending ondepending on–Limb: Leg approx. 3 times strength of armLimb: Leg approx. 3 times strength of arm–Direction exerted: Strength may decrease by Direction exerted: Strength may decrease by 50% 50% –Preferred hand/arm/leg: Strength may vary by Preferred hand/arm/leg: Strength may vary by 40–50%40–50%Left and right leg strengths do not differ Left and right leg strengths do not differ appreciably.appreciably.Other CharacteristicsOther CharacteristicsAgeAgePersonal spacePersonal spaceAge of WorkforceAge of WorkforceBirth rate is declining.Birth rate is declining.Additional workers must come Additional workers must come from immigrationfrom immigrationLonger work hoursLonger work hoursDelayed retirementDelayed retirementOlder workers must be Older workers must be considered.considered.Personal SpacePersonal SpaceIntimate (0 – 18 in.)Intimate (0 – 18 in.)Personal (18 – 48 in.)Personal (18 – 48 in.)Social (4 – 12 ft)Social (4 – 12