WORK-SPACE DESIGNWORK-SPACE DESIGN

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We will cover:- Introduction-Anthropometry

-Static Dimensions-Dynamic (Functional) Dimensions-General Discussion About Static And Dynamic Dimensions

-Use Of Anthropometric Data-Principles In The Application Of Anthropometric Data

-Designing For Extreme Individuals-Designing For Adjustable Range-Designing For The Average

-Suggestions For Using Anthropometric Data In Design-Posture Consideration

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-Classification of Human-Machine Systems-Characteristics of Systems

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INTRODUCTIONINTRODUCTION

Many of the tools, facilities and workplaces are Many of the tools, facilities and workplaces are found to be not suitable to human use because of found to be not suitable to human use because of their design features.their design features.

Examples include: uncomfortable chairs, low or high Examples include: uncomfortable chairs, low or high sinks in toilets and kitchens, clothes, repairing tools sinks in toilets and kitchens, clothes, repairing tools and equipments.and equipments.

These examples are the results of failure to design These examples are the results of failure to design equipment and facilities to fit the equipment and facilities to fit the physical physical dimensions of the peopledimensions of the people who will who will use themuse them. .

This chapter will focus on how things can be This chapter will focus on how things can be designed to fit the physical dimensions of people. designed to fit the physical dimensions of people.

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ANTHROPOMETRYANTHROPOMETRYIt deals with the measurement of the It deals with the measurement of the dimensions and other physical characteristics dimensions and other physical characteristics of the body such as the volumes, center of of the body such as the volumes, center of gravity and masses of body segments.gravity and masses of body segments.

Body dimensions are fundamental to a wider Body dimensions are fundamental to a wider range of design problems. range of design problems.

Body measurements could be static or Body measurements could be static or dynamic (functional). Engineering dynamic (functional). Engineering anthropometry is concerned with the anthropometry is concerned with the application of both types of data to the design application of both types of data to the design of the things people use.of the things people use.

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Static DimensionsStatic Dimensions Taken when the body is in a fixed (static) position.Taken when the body is in a fixed (static) position.

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

Many dimensions can be measured (NASA Many dimensions can be measured (NASA Anthropometric source book contains 973 Anthropometric source book contains 973 measurements from 91 worldwide surveys).measurements from 91 worldwide surveys).

Many of the dimensions have specific applications Many of the dimensions have specific applications (helmets, gloves, etc.). But many body features (helmets, gloves, etc.). But many body features dimensions also have general utility. See dimensions also have general utility. See figure 13-1 and and table 13-1. (Also see the figures in (Also see the figures in BODYSPACE).BODYSPACE).

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What does a 5What does a 5thth percentile or 95 percentile or 95thth percentile mean? percentile mean?The answer is that the percentile refers to the The answer is that the percentile refers to the percent of the population that have a dimension percent of the population that have a dimension below the stated dimension.below the stated dimension.How can we calculate any percentile value?How can we calculate any percentile value?

Use the Formula: Use the Formula: X(p)=m + szX(p)=m + sz You will also need to use the You will also need to use the z-values table.

Body dimensions vary as a function of age, sex, and Body dimensions vary as a function of age, sex, and for different ethnic populations (see for different ethnic populations (see figure 13-2).).

Stature and related dimensions generally increase Stature and related dimensions generally increase until the late teens or early twenties. They then until the late teens or early twenties. They then remain relatively constant and then decline when remain relatively constant and then decline when entering into old age.entering into old age.

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Figure 13-3a illustrates the differences between Figure 13-3a illustrates the differences between the dimensions due to sex difference and figure the dimensions due to sex difference and figure 13-3b illustrates the differences due ethnic 13-3b illustrates the differences due ethnic reasons. reasons.

Differences in dimensions between people Differences in dimensions between people working in different occupations are also common working in different occupations are also common (occupational differences).(occupational differences).

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Dynamic (functional) DimensionsDynamic (functional) Dimensions

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

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

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General discussion about static and dynamic General discussion about static and dynamic dimensionsdimensions

Static anthropometric data exists more than Static anthropometric data exists more than dynamic anthropometric data even though dynamic dynamic anthropometric data even though dynamic data are more representative of actual human data are more representative of actual human activities.activities.

Although there is no clear way of converting static Although there is no clear way of converting static data to dynamic, the following recommendations data to dynamic, the following recommendations may be helpful:may be helpful:

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Reduce heights (stature, eye, shoulder, hip) by 3 Reduce heights (stature, eye, shoulder, hip) by 3 percent.percent.

Elbow height: no change, or increase by 5 percent Elbow height: no change, or increase by 5 percent if elevated at work.if elevated at work.

Knee or popliteal height, sitting: no change, Knee or popliteal height, sitting: no change, except with high-heel shoes.except with high-heel shoes.

Forward and lateral reaches: decrease by 30 Forward and lateral reaches: decrease by 30 percent for convenience, increase by 20 percent percent for convenience, increase by 20 percent for extensive shoulder and trunk motions.for extensive shoulder and trunk motions.

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USE OF ANTHROPOMETRIC DATAUSE OF ANTHROPOMETRIC DATA

The data should be representative of the population The data should be representative of the population that would use the item designed.that would use the item designed.

If designing for general purposes, the features must If designing for general purposes, the features must accommodate a broad range of people. But when accommodate a broad range of people. But when items are designed for specific groups, the data used items are designed for specific groups, the data used should be specific for such groups.should be specific for such groups.

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PRINCIPLES IN THE APPLICATION OF PRINCIPLES IN THE APPLICATION OF ANTHROPOMETRIC DATAANTHROPOMETRIC DATA

Three general principles:Three general principles:

1.1. Designing for extreme individuals:Designing for extreme individuals: All should be accommodated.All should be accommodated.

Sometimes, a single design dimension is a Sometimes, a single design dimension is a limiting factor that might restrict the use of the limiting factor that might restrict the use of the facility for some people. This factor can dictate facility for some people. This factor can dictate either a maximum or a minimum value of the either a maximum or a minimum value of the dimension in question. dimension in question.

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Designing for the maximum population value is the Designing for the maximum population value is the strategy used if a given maximum (high) value of strategy used if a given maximum (high) value of some design feature should accommodate all some design feature should accommodate all (almost) people.(almost) people.

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

Designing for the minimum population value is the Designing for the minimum population value is the strategy used if a given minimum value (low) of some strategy used if a given minimum value (low) of some design feature should accommodate all (almost) design feature should accommodate all (almost) people.people.

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

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2.2. Designing for adjustable range:Designing for adjustable range: Some features of equipment or facilities can be Some features of equipment or facilities can be

designed so that they can be adjusted to the designed so that they can be adjusted to the individuals who use them.individuals who use them.

Examples: automobile seats, office chairs, desk Examples: automobile seats, office chairs, desk heights.heights.

The practice is to provide for adjustments (of The practice is to provide for adjustments (of the relevant dimensions) to cover the range the relevant dimensions) to cover the range from the 5from the 5thth percentile female to the 95 percentile female to the 95thth percentile male of the population.percentile male of the population.

What will be the percent of the population What will be the percent of the population covered if the above mentioned range is used?covered if the above mentioned range is used?

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Designing for an adjustable range is the preferred Designing for an adjustable range is the preferred method of design. But sadly, it is not always possible.method of design. But sadly, it is not always possible.

3.3.Designing for the average:Designing for the average:

The cheapest and most quick method. But does an The cheapest and most quick method. But does an average person exist?average person exist?

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

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

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

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SUGGESTIONS FOR USING ANTHROPOMETRIC SUGGESTIONS FOR USING ANTHROPOMETRIC DATA IN DESIGNDATA IN DESIGN

1.1. Specify the body dimensions that are important Specify the body dimensions that are important in the design.in the design.

2.2. Define the population to use the facility or Define the population to use the facility or equipment. This will establish the dimensional equipment. This will establish the dimensional range that needs to be considered.range that needs to be considered.

3.3. Determine what principle should be applied Determine what principle should be applied (average, extreme, or adjustable).(average, extreme, or adjustable).

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4.4. Determine the percentage of population to be Determine the percentage of population to be accommodated.accommodated.

5.5. Locate the appropriate anthropometric tables to be Locate the appropriate anthropometric tables to be used and extract the relevant values.used and extract the relevant values.

6.6. Add the appropriate allowances (clothing, shoes Add the appropriate allowances (clothing, shoes etc…).etc…).

7.7. Build a full-scale mock-up of the equipment or Build a full-scale mock-up of the equipment or facility and have representative people of large and facility and have representative people of large and small user (of the population) try it. small user (of the population) try it.

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POSTURE CONSIDERATIONPOSTURE CONSIDERATIONPosture is defined as the relative orientation of the Posture is defined as the relative orientation of the parts of the body in space. parts of the body in space.

It is determined by the connection (relationship) It is determined by the connection (relationship) between the dimensions of the body and the between the dimensions of the body and the dimensions of the workspace.dimensions of the workspace.

The connection may be physical (seat, worktop) or The connection may be physical (seat, worktop) or visual (location of displays and tools).visual (location of displays and tools).

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

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To maintain a certain posture over a period of time, To maintain a certain posture over a period of time, the muscles must be used to counteract the external the muscles must be used to counteract the external and internal forces acting on the body. and internal forces acting on the body.

A varied working posture (dynamic) is better than a A varied working posture (dynamic) is better than a fixed (static) working posture.fixed (static) working posture.

Simple guidelines for better posture are offered in Simple guidelines for better posture are offered in Pheasant’s book (page62 & 63).Pheasant’s book (page62 & 63).