Human factors in ergonomics and interior design

Env Design

Anthropometry

Physical characteristics of the body:

Volume

Center of Gravity

Intertia

Masses of specific body segements

Two types of body measurements:

Static Dimensions

Measures of body in fixed (static) position (eg. Skeleton; head circumference)

Vary with age, sex, ethnicity

Functional (Dynamic) Dimensions

Measured under conditions of movement or activity (eg. Operating steering wheel, using a mouse)

Can use somatography to show multiple angles and views of a person in action

Engineering Anthropometry -- the application of above data (body measurements) to the design of the things people use.

Applications/How to Apply Anthropometry to Design

Represent the population (not all items can be designed "one size fits all")

Three (3) Principles of Applying Anthropometry to Design

Design for Extreme Individuals

Accommodate for all persons by designing for the biggest possible extreme in weight, height, etc.

Can accommodate most within reason

Designing for Adjustable Range

Adjustable chairs, eg. Is preferred method but not always possible

Designing for the Average

Sometimes considered a "cop-out" because there is no average person

Sometimes necessary, as with counter heights at stores

Complexity of Multiple Dimensions/Measures in One Design

Composite measures, multiple dimensions with following suggestions:

1. Determine the relevant body dimensions for the item (eg. Sitting height for design of a car seat)

2. Define the user population (age, gender, etc.)

3. Determine the principle (extreme, adjustable range, for the average)

4. If relevant, apply percentage of the population to be accommodated

5. Use pre-designed anthropometric tables for the target population

6. Allowances for clothing, shoes

7. Build a full-scale mock-up

Designing Work Spaces

Work Space Envelope- "the three dimensional space within which an individual works" (p. 424).

Concepts related to Work Space Envelope

Out of Reach Requirements (distances a person has to reach)

Objects that need to remain out of reach for safety or security

Clearance Requirements (minimum space needed to move)

Esp for maintenance personnel (eg. Crawl spaces)

1. For Seated Personnel

Functional arm reach

Effects of manual activities (what the person actually does)

Effects of apparel (eg. Impact of winter coats on drivers)

2. For Standing Personnel

Center of gravity

Zone of convenient reach

Design of Work Surfaces

Horizontal work surfaces

Normal Area: "Area that can be conveniently reached with a sweep of the forearm while the upper arm hangs in a natural position to the side" (p. 432).

Maximum Area: "Area that could be reached by extending arm from shoulder" (p. 432)

Work Surface Height = height of upper surface measured from floor

Seated work surface height and arm posture (elbows at 90 degrees)

Seated work surface height and thigh clearance (accommodate thighs of largest user)

General Principles for Seated Work Surfaces

1. If possible, make it adjustable

2 Work surface level places working height at elbow height

3. Adequate thigh clearance

Standing work surface = similar principles (design for largest user; take into account elbow height)

General Principles of Seat Design

1. Promote lumbar lordosis (naturally concave shape); kyphotic (convex -- bad!)

2. Minimize disk pressure (unsupported sitting can create pressure)

3. Minimize static loading of back muscles (allow back to recline)

4. Reduce postural fixity (sitting in one position for long time)

**provide for easy adjustability -- can increase productivity in workplace! But must be easy to adjust