Anthropometrics • Standing Working Heights • Sitting Working Heights • Reaches • Gender Strength Differences • Postural Strength Differences
Design so the large can fit, the small can reach and the weak can lift, lower, push, pull and carry. Anthropometrics
Anthropometric Measurements Anthropometrics looks at the variability between people and utilizes principles of statistics to do this.
Percentiles • Body dimensions can be plotted on a graph with the measurements on the horizontal x axis increasing toward the right from the zero point. The frequency of occurrences is plotted on the vertical y axis, increasing toward the top from the zero point.
Anthropometrics and Design • It is not customary to design for everyone. The military has chosen to exclude 5% at the small end of the curve and 5% at the large end of the curve, thereby accommodating 90 of the measured population in the Military Standards
Anthropometrics • 50th Percentile Male Reach = 30.9” • 50th Percentile Female Reach = 28.0” • 95th Percentile Male Reach = 33.3” • 5th Percentile Female Reach = 25.8”
Things To Consider • Determine what body dimensions are relevant. • Determine what population group is relevant. • Use the anthropometric data as a guide and a place to start. It does not replace employee input. • Just because something does not fall within anthropometric guidelines does not mean it is necessarily a significant ergonomic risk. • When designing workstations or equipment, you will never be able to accommodate everyone. Try to accommodate as much of the population as you can, given the space and cost parameters you have to work within.
Standing Workstation Height NIOSH 1997 Publication, Elements of Ergonomics Programs
Horizontal Reach Envelopes NIOSH 1997 Publication, Elements of Ergonomics Programs
Choosing Working Postures • Standing • For heavy, bulky loads • When frequent movement is required • When there is no knee room under the equipment • Where there is limited front-rear space
Choosing Working Postures • Sitting • For accurate control, fine manipulation. • For continuous light manipulation work. • For close visual work with prolonged attention. • For limited headroom, low work heights.
Sagittal Reach Envelopes • As the arm moves though its normal range of motion it creates an arc and creates the primary reach arc and the secondary reach arc. The primary reach arc places minimal stress on the shoulder and low back. The secondary reach envelope can place stress on the shoulder and increases stress on the low back. Reaching beyond the secondary reach arc will require forward bending and significantly increases stress on the low back.
Ear-Eye-Line • The EE line is determined by using the ear-hole and the junction of the eyelids. The EE line describes the posture of the head and serves as reference for the angle of the line of sight.
Line of Sight • The line of sight connects the pupil with the visual target. Eye movement within about 15 degrees above and below the average line-of-sight angle is still comfortable.
Practical Application of Anthropometrics • This video clip from NASA shows how Anthropometric data was applied to the design of equipment.