INTD 301 FURNITURE AND FITTINGS

ANTHROPOMETRY AND ERGONOMICS

Joshima V.M., University of Nizwa

Anthropometry

Anthropometry is the science of determining anatomical

measurements and understanding the physiology of

human body.

Research in this area generate statistics/ data from:

Different age groups

Different Body sizes

Different ethnicities

Different gender

To understand the similarities and differences in human form.

Anthropometry

It deals with the measurement of the human

dimensions and other physical characteristics of the

body such as the volumes, center of gravity and

masses of body segments.

Knowledge of these features are important for

furniture design to determine the dimension, size,

shape and material of furniture design.

Anthropometric dimensions

Static Dimensions

• Taken when the body is in a fixed (static) position.

• They consist of skeletal dimensions (between the centers of joints) or contour dimensions (skin-surface dimensions such as head circumference).

Anthropometric dimensions

Dynamic (functional) Dimensions

• Taken while the body is engaged in some physical activity.

• In most physical activities, the individual body members function together (many members are moved and the relative position is affected).

Use of Anthropometric Data

Use of Anthropometric Data

How to use Anthropometric Data?

1. Determine the body dimensions which will be important in

the use of the system.

2. Define the relevant (user) population. (women, children etc)

3. Which design principle will be used?

4. What percentage of the population it is to be designed for?

5. Determine the relevant value from the anthropomorphic

tables.

6. Add appropriate allowances for special situations.

Bulky clothing worn in cold weather

Protective clothing worn by hazardous duty personnel

Use of Anthropometric Data

Design Principles

1. Design for extreme individuals

1. Design for the maximum population value

2. Design for the minimum population value

2. Design for adjustable range

3. Design for the average

Intended User: Design Principles in Application

1. Design for extreme individuals: All should be accommodated. Most designs cover 5th through 95th percentile.

Design for the maximum population value is the strategy used if a given maximum value of some design feature should accommodate all people.

Examples: heights of doorways, strength of supporting devices such as ropes.

Design for the minimum population value is the strategy used if a

given minimum value of some design feature should accommodate all people.

Examples: The distance of a control button from the operator, the force required to operate the control.

2. Design for adjustable range:

Some features of equipment or facilities can be designed

so that they can be adjusted to the individuals who use

them.

Examples: automobile seats, office chairs, desk heights.

The practice is to provide for adjustments (of the relevant

dimensions) to cover the range from the 5th percentile

female to the 95th percentile male of the population.

Designing for an adjustable range is the preferred

method of design. But is not always possible.

3. Designing for the average:

The cheapest and most quick method.

A person who is average on one or few dimensions will surely not be average on many dimension. This is because there is no perfect correlation between the dimensions.

Designing for the average is common and often is acceptable in situations involving non critical work where it is not appropriate to design for the extreme and also where adjustability is impractical.

Example: A checkout counter at a supermarket is built for the average customer.

Percentile human

Anthropometric dimensions for each population are

ranked by size and described as percentiles.

It is common practice to design for the 5th percentile

(5th%) Female to the 95th percentile (95th%) male.

The 5th% to 95th% range accommodates approximately

90% of the population.

Example: design a stool to accommodate the 95th percentile of

male body weight. That should include most people.

Design a tray to be carried by workers to be light enough for

the 5th percentile of women

Body Dimensions

Ergonomics

‘Ergonomics’ is the study that focuses upon the task and

performance of task.

Task is any activity done by human beings. Eg. Eating,

writing, typing, sleeping, sitting, drafting etc.

The term ‘Ergonomics’ comes from the greek words

‘ergos’ means ‘work’ and ‘nomoi’ means ‘natural laws’.

Ergonomic Research seeks to establish a healthy fit

between:

Ergonomic Research

Performing a task

Designed product

Limits of human body

Ergonomic design considers the following factors:

Body posture.

Physical limits of reaching, pulling, lifting and pushing.

Disabilities and injuries occurring in laboratories, factories and

office environments.

The effort is to make work and tools more healthier, safe

and environmentally green

Considerations

Posture

Posture is defined as the relative orientation of the parts of the body in

space.

It is determined by the connection (relationship) between the dimensions

of the body and the dimensions of the workspace.

The connection may be physical (seat, worktop) or visual (location of

displays and tools).

Posture

If the dimensional match is inappropriate, the short-term and long-term consequences of the well-being of the person may be severe.

To maintain a certain posture over a period of time, the muscles must be used to counteract the external and internal forces acting on the body. A varied working posture (dynamic) is better than a fixed (static) working posture.

Common workplace postures

Standing

Sitting

Reaching

Moving

Standing

Some users may need or want to

stand while at their

workstations.

Desk height for a standing

operator can range from 28-

43“depending on whether the

desk is for precision, light, or

heavy work.

When selecting desk height it is

important to remember that the

top line of text on a computer

monitor should be located at eye

level or slightly below.

Sitting

Maintaining the neutral, or standing shape of the lumbar,

or lower spinal area, is important for comfort and

posture.

A good seated posture is one that is comfortable and

does not put a lot of stress or strain on the user’s

buttocks, back, or arm muscles, and allows the user’s feet

to be on the floor.

Reaching

While sitting or standing, an individual at

work will usually have to reach for

something.

When designing products, consider how

much individuals will have to reach in order

to minimize awkward or unhealthy positions.

Moving

Users will move around in their environment to file

papers, answer a phone, or stretch.

Chairs and other devices in the workspace can allow the

user to easily get up and move around without having to

move armrests, adjust other chair settings, or put undue

stress on the body.

Physical Limits: Good and Bad Zones

There are 4 different zones that a user might encounter while sitting or standing. These zones are ranges where body limbs can move freely.

Zone 0 (Green Zone) Preferred zone for most movements. Puts minimal stress on muscles and joints.

Zone 1 (Yellow Zone) Preferred zone for most movements. Puts minimal stress on muscles and joints.

Zones 0 and Zone1 Include smaller joint movements.

Zone 2 (Red Zone) More extreme position for limbs, puts greater strain on muscles and joints.

Zone 3 (Beyond Red Zone) Most extreme positions for limbs, should be avoided if possible, especially with heavy lifting or repetitive tasks.

Zones 2 and 3 represent more extreme positions. Motion in these ranges puts more strain on muscles and tendons and could lead to the

development of musculoskeletal disorders.

Universal Design

Most people will have some physical limitations at any

point of their life like broken bones, pregnancy or aging

etc.

While designing products this becomes an important

consideration.

Designer should identify these special needs, including

people with disabilities.

Universal design refers to broad-spectrum ideas meant to

produce buildings, products and environments that are

accessible to both people without disabilities and with

disabilities.

PRINCIPLES OF UNIVERSAL DESIGN

1. Equitable use : The design is useful and marketable to people with diverse

abilities.

2. Flexibility in use: The design accommodates a wide range of individual

preferences and abilities.

3. Simple and intuitive use: Use of the design is easy to understand,

regardless of the user’s experience, knowledge, language skills, or current

concentration level.

4. Perceptible information: The design communicates necessary information

effectively to the user, regardless of ambient conditions or the user’s sensory

abilities.

5. Tolerance for error: The design minimizes hazards and the adverse

consequences of accidental or unintended actions.

6. Low physical effort: The design can be used efficiently and comfortably,

and with a minimum of fatigue.

7. Size and space for approach and use: Appropriate size and space is

provided for approach, reach, manipulation, and use, regardless of the user’s

body size, posture, or mobility