Technical systems must be supervised or operated by humans in all aspects of

human-machine-environment systems, e.g., in the household, automobiles, consumer

electronics, or in traffic. These examples show – and everyone has probably had

experience with these – that the design of systems provided to humans is not always

optimal, i.e., user-friendly. In order to offer hazard-free handling and error-free human-

machine interaction, it is vital that the characteristics and capabilities of future users

are taken into account. In addition, the ergonomic design of products has substantial

meaning for the acceptance of appliances. A mobile phone, for example, that is more

complicated to operate than competitors’ products (because fundamental ergonomic

principles were not incorporated) is no longer capable of competing in today’s market.

Early inclusion of ergonomic aspects during product development thus also leads to a

better market position and a reduction in costs due to later product changes.

Design of products, however, continues to be not seldomly left up to designers and

draftspeople who do not have specific knowledge on ergonomics. This can clearly be

seen in the design of current consumer electronics products, computer software and

mobile telecommunications: the user is completely overwhelmed by the excess of

functionality and highly complex system structures (e.g., nested menus, hidden

functions).

What is Product Ergonomics?

What is Usability Engineering?

Product ergonomics involves adapting products to their users’ characteristics so that

the products can be used more easily.

Anthropometry in product ergonomics primarily involves consideration of measures

and measurement ratios in the design of future product and work places. Based on

body dimensions, cars, for example, have their seating geometry, layout of operating

elements (steering wheel, gear shift, pedals), operating force as well as the visibility of

their instruments laid out.

The principles introduced in the information technology design can usually also be

transferred to the design of software.

The layout of the car console (here: Daimler’s Innovative Concept Study) places high

demands on anthropometric design. Included is the visibility/outside view and readability of

indicators and instruments, obscurities (e.g. due to steering wheel or operating elements)

as well as the range (reachability and operation of operating elements) or the actuating

force (operation of pedals, switches and steering elements). Furthermore, dis(comfort) due

to confining posture must especially be considered, particularly for driving long distances.

The most prominent innovations illustrated in the image above is an imaginative new

driving control system which allowed the driver to control all vehicle movements by means

of sidesticks positioned in the door trim panels and in the centre console of the coupé

study. Moving the sidesticks to the left or right steered the vehicle, pushing the levers

forwards accelerated it, pulling it back applied the brakes. The interior of the F 200

Imagination was completely devoid of conventional control and connecting components,

such as a steering wheel, steering column or pedals – each and every command from the

driver was transmitted electronically, a system which the experts referred to as "drive-by-

wire". The F 200 Imagination study also presented the Mercedes design team with an ideal

opportunity for showing how the omission of a steering wheel and pedals opens up whole

new possibilities for the interior styling and controls of the passenger cars that we will be

driving in years to come. The driving control system in the F 200 Imagination was coupled

to an active suspension system which adapted the vehicle's suspension and damping

characteristics to the current handling conditions. The result was improved driving safety

and ride comfort, something which made the F 200 a mobile laboratory for the Active Body

Control system which premiered in Mercedes-Benz series-production models in 1999.

The eye-catching steel panels bordering the glass roof of the F 200 Imagination also

housed electronic cameras which removed the need for interior and exterior mirrors.

Instead, monitors fitted inside the study's cockpit kept the driver fully informed of what was

going on behind the car.

Source: http://www.daimler.com

The second example is of an airplane cockpit for a study of a passenger plane with

two motors based on the AIRBUS cockpit concept. Through the airplane’s outer

structure the outside view and the position of the pilot is given in the cockpit. Aside

from the numerous SAE, JAR and FAA standards, particularly long operational

durations and the wide spectrum of global users are typical for cockpits.

From a anthropometric perspective, taking visibility into consideration, i.e. outside

view at start and landing and during taxiing on the runway, and visibility of

instruments, is just as important as the reachability of operating instruments through

various safety belt functions with a 5-point belt. With the Fly-by-Wire artificial steering

forces contribute to easier steering. Paying attention to posture comfort is especially

important for long flights (transatlantic).

A similar concept is found in several AIRBUS airplanes and makes the re-training of

pilots from one type to another more simple. This is necessary in almost all airlines

during the course of a career/promotion. Actually, the user interface of an

A319/320/321 can be distinguished from that one of a A330/A340/A380 only by the

design. But regardless the same user interface elements, it is important to say that

flight characteristics and flight dynamics can be significantly different.

In practice, mostly a mixture in design exists:

Purely prospective/planning ergonomics is impossible e.g. in automobile creation

since standards and pre-designs must be taken into consideration as a basis. A

benefit of a pre-design is, through the identification with the brand, an easy transition

from one type to the next: this minimises the training time and increases the reliability.

A continuous modification of existing driver workplaces results, which leads to a

mixture of various ergonomic approaches.

The later changes and counterbalancing measures are recognised and put into

action, the higher are the resulting costs and necessary recalls. A strict adherence to

deadlines with simultaneous high quality is increasingly more difficult, especially in

relation to the increasing relevance of the “just in time” delivery and the

consequences of delays

There is a close relationship between general ergonomic design criteria and

anthropometric design. Therefore, the maximum forces acting on humans are to be

taken into account in terms of harmlessness. Obviously, a failure to notice can easily

lead directly to health damages (e.g. slipped discs during lifting). The feasibility must

be ensured through a meaningful layout of operating elements (reachability,

operation) and instruments (visibility). A product such as an automobile cannot be

steered if important elements like the steering wheel or the pedals are not reachable

for the majority of users. In regard to higher criteria such as tolerability and avoidance

of interference, damaging body postures and overstraining are to be avoided; it is also

important to ensure a high level of comfort through the design. Personality

development answers general questions regarding “well-being”. However, aspects of

colour design for the instruments as well as design aspects are more related to

aesthetic levels.

Three requirements of ergonomic design of products can be derived from slide 10-10.

The historic foundations of anthropometry are, aside from the representation of

humans in art, especially found in architecture. As humans were often seen as an

image of God, “godly” and perfect proportions were thought to be made possible by

incorporating human proportions into building design. Thus, many medieval

structures, particularly sacral buildings, are based on human proportions.

Body measurements were also used in daily life as a form of measurement. The

reason for this is the lack of a universal relative measurement system, such as the

“Urmeter”. Instead, available body measurements would be used: the inch is the

length of the first thumb joint, a cubit the length from the elbow to the tip of the finger,

and paths could be measured with the even “Feldrute” in which 16 people would line

up in a row, one behind the other.

With the Renaissance anthropometry was used in medicine, especially in anatomy, in

order to scientifically identify the skeletal structure and the inner composition of the

human body.

Da Vinci in particular occupied himself with solid results about the build of the human

body. His goal was a representation in beautiful artwork, but also the practical use of

the acquired anthropometric insights in the design of tools. As appliances or tools

were until now only developed through “evolution”, i.e. good designs were pursued,

bad ones were discarded, a goal oriented, almost scientifically engineered design

was now possible.

There are numerous anthropometric measures. These days the principle that counts

is: what can be measured will be measured. In sight of product ergonomics, there is

still a large portion of the total measure that is interesting. These are listed here. An

overview of large data collections can be found in the standards. Besides body sizes,

general conditions for data collection can be found here. These must be adhered to in

implementation since errors may otherwise occur. For example, most body sizes are

collected from unclothed persons in standard positions (perpendicular seating): this

case can rarely be found in practical usage however. Therefore, safety margins are

necessary during product design. Additionally, differentiation/characterisation of

measured samples must be taken into account since there are great differences in

body sizes as well as body proportions between the sexes, age groups and regional

groups. Different body sizes are often combined for general characterisation of

physique and corpulence. Thus, heavy-set short people can openly be distinguished

from lean people, which can then also be taken into consideration during product

design.

The limitation of using only one value for the description of body size (e.g. the

average) is not reasonable since more than one user will be using a product later on.

Instead, percentages are used in anthropometry which cover a range. A percentage

indicates how much of the population fall below the measurement. The 5th percentile

thereby refers to a short person since only 5% of the entire population are shorter.

The 95th percentile is a tall person, since 95% of the population is shorter and only

5% is taller. Length measurements such as body height are normally distributed so

that a simple relation between percentile and mean/standard deviation exists. The

mean relates to the 50th percentile (50% are shorter than that measurement) and the

5th, i.e. 95% less than the mean, or in addition to 1.96 times the standard deviation. In

practice, the 5th and 95th percentile are used.

As can be seen from the diagram, there are further differences between the user

groups that must also be considered: differences in sex are especially important here.

Thus, a body height of an average female (50th percentile) corresponds to a rather

short male (5th percentile). Similarly, sex-specific differences also exist for other body

sizes and proportions. A mixing of data for females and males would not make sense

since the differences would no longer be sufficiently taken into consideration. Instead,

different analyses for product ergonomics are necessary.

For safety-relevant measurements the 1. or 99. percentile is usually used.

The values given in the table are based on statistically validated measurements of

persons from the Federal Republic Germany (DIN 33402).

In the industry, work materials and workplaces, whose measurements are to

correspond to the body dimensions of the person, cannot always be designed for

each individual user due to economic reasons. Therefore, it is necessary to establish

a basis for the adaptation of work materials and the workplace to the body form of as

many users are possible by using statistical data. Thereby, depending on task and

usage type, it is possible to attain different workplace sizes, adjustments or a design

applicable to all users.

Aside from differentiation between the sexes, differences between age groups,

regions and clothing must also be included. This is especially true for when products

are designed for global markets.

Region/Cultural dependencies of measurements: A 95. percentile Vietnamese, and

thus a notably tall man from this region, is approximately equal to a 10. percentile

central European. The range from the .5 to the .95 percentile man from the “South

East Asian” region amounts to 153-172 cm.

Also see: Sanders & McCormick, 1993, pp. 420ff

Through the course of time a general increase in body size, especially in industrial

nations, can be noted. This occurrence called the increase of body dimensions takes

place primarily due to improvements in living conditions (hygiene, nutrition, work

conditions).

An extrapolation for the adaptation of older tables or to the estimation of future ones

remains problematic since the increase in sizes do not occur continuously, and no

reliable prediction about a possible end of the increases is available.

However, as an example, increase of body dimensions was calculated up until the

year 2050 for the Airbus A380 so that passengers will still have comfortable seating

then. (Bauch, 2001, www.haw-hamburg.de/pers/Scholz/dglr/bericht0101/Bauch.pdf)

Height and corpulence

Body sizes are not independent of one another, rather, they strongly correlate with

each other. Body sizes within a group (e.g. high and long measurements as well as

reaches) possess a high correlation to one another, while the correlation between

body sizes of different groups is practically non-existent: not every large person is

overweight!

The statistical tool of factor analysis can be used based on the correlations in order to

combine similar sizes. In anthropometry something similar occurs through the use of

index values.

There are three types of body sizes: the body height, the corpulence and the

proportion (sitting giant/sitting dwarf).

An optimal product design takes into consideration not only small or large people

(height), but also the corpulence and proportions. Instead of two values (big, small)

there are actually 8:

Big, slender, short-legged

Big, corpulent, short-legged

Big, slender, long-legged

Big corpulent, long-legged

And the same for small persons.

Differences between sex and age group must also be considered.

Muscle force is a physical strength that works through the activity of the muscles

within the body. There is a difference between static and dynamic muscle force. Static

muscle force is the physical strength that occurs without a change in the length of the

muscle during its activity. Dynamic muscle force, however, occurs during the change

in length of the muscle in its activity.

Inertia force is a physical strength that works as a force of inertia, e.g. dynamically as

accelerating force, force of deceleration, or centrifugal force at mobile workplaces, or

statically as own weight.

Applied force is a physical strength that works outward from the body. It results from

inertia force, muscle force, or both. Inertia force and muscle force can reduce or

increase their strength depending on amount and direction.

From the force-releasing body parts the applied force is split into e.g. arm, hand, leg

or finger force; from the force direction the applied force is split into e.g. vertical or

horizontal force.

The applied force is differentiated according to the force of attraction and the force of

pressure from the sense of direction of force.

The specifications of DIN 33411-4 apply to an upright unconstrained body posture with non

shifted parallel foot position on a foot spacing of 30 cm. The given values of the maximum

static action forces were determined on fixed positioned handles with a short-term maximum

contraction force of the worker. A cylindrical grip was used with a diameter of 30 mm, which

has been operated without tools. These are average values of the maximum possible static

action forces that apply to certain collectives (e.g., men aged 20 to 25 years) and not

representative for the total population. The representation is in the form of isodynes. The

transferability of the data must be checked for differing operating situations (e.g. in terms of

posture or the required force direction). Maximum static action forces from other operating

situations for example are presented in DIN 33411-3 and DIN 33411-5.

Example: From a side angle ß = 30°, an elevation angle = 0° and a relative range a = 50% a

maximum driving force of F=150 N results for the vertical upward arm forces performed by a

male person.

Human action forces play a role for all mechanical performances. They occur during

the maintenance of body positions, during the execution of free or steered body

movements or its extremities, during the use of work tools, in the operation of

operating elements, or during the manipulation of loads. Physical strengths are

developed as muscular strengths within the body, work as mass force (force of

inertia) from the outside onto the body or are transferred by the body as action forces

to the outside.

Physical forces can be used for the design of work media for various goals. For

example, data collection from the viewpoint of comfortable usage could take place for

how to design the operating elements’ operational resistances that must be served in

an automobile. For the continuous manual regulation of dynamic processes, however,

the question remains regarding which level of operating resistance operating

elements must have in order to deliver an adequate proprioceptive (realisation of

stimuli arising from own organism) response about the movement procedure.

DIN 33411, Teil 1: Körperkräfte des Menschen – Begriffe, Zusammenhänge,

Bestimmungsgrößen (Physical strengths of man – concepts, interrelations, defining

parameters)

Maximum isometric forces (isodynes): DIN 33411, Teil 4, S. 1:

Also see: Sanders & McCormick, 1993, pp. 248-254

Dynamic (Functional) Dimension: Active area of the hand-arm-system

Aside from measures for the performance of functions (work areas, areas of joint

movement), safety measures (safety, minimum and maximum distances) and space

requirement measures (space requirements, compensational movement) can also be

differentiated between.

Aside from static anthropometry it is getting more and more important to account for

dynamics since in reality, postures are never static but always fluctuate around

average. Especially work is always bound to deliberate movements.

For movement planning, a comprehensive methodology to capture and document

data like in anthropometry is not available for yet. Whereas for anthropometry, it is

human body dimensions and corpulence within groups of people, there is not such a

thing for movements.

There is even a stronger diversification and variability of movements. Even the same

person does never move exactly the same way twice. So beside of the inter-individual

diversification, there is also an intra-individual one. Hence, for movement planning,

the ergonomic planner has to rely on estimations of spacial requirements or single

movement tracks.

A specific movement is partitioned into several phases. The actual movement first has

a design phase in which a movement pre-programming takes place. The movement

itself divides into two other phases: the ballistic and the visually controlled phases.

The first phase serves for quick guidance to the goal, while a fine-tuning occurs in the

second phase.

The temporal division of these two phases amounts approximately 2/3 to 1/3.

Approaches of varying complexity are available for the characterisation of movement:

Temporal and spatial characteristic data are easy to use, yet simplify a movement too

much and are therefore only suitable for narrowly outlined special areas (e.g.

methods-time-measurement or work-factor-processes in the scope of production

planning).

Motion paths, or trajectories, express spatial relationships. The problem is the

summarization and meaningful preparation and presentation of the multitude of

possible motion paths.

Biokinematic models are based on different approaches (e.g. biomechanic or inverse

kinematics) and allow an exact replication of individual movements for digital human

models or in simulations. However, the variability of the movements is also a problem

here. Still, due to their high level of clarity and face validity of presentations, they have

managed to be supported by all human models.

Fields of vision (upper left: different areas of the field of view – pay attention to colour

dependencies!) and thereby the recognisability and readability of instruments

(dependent on vision – Visus 1 (normal): 1 arc minute resolution) are at least equally

as important as anthropometry.

The design of vehicles begins with a fictitious eye-point (Design-Eye-Point, airplane)

or from an eye ellipse (auto) in which the eye of the future user exists.

Airplane (bottom left):

Design Eye Position (eye-point):

... Is a set point relative to the airplane structure upon which the eyes of the pilot

are to be in the normal seating position (SAE ARP 4202); fixing of the pilot’s

position in the cockpit; seating adjustment area is to be fixed so that all pilots can

attain positions in the DEP

Line of Sight

The line of sight provides the line of vision during landing; sloped downward (angle

of incidence during landing)

In practice, the verification of the sight requirements can also be done through lines of

sight in CAD or in technical drawings. It is easier to do so with human models (bottom

right) which present the fields of view as cones, or that directly calculate the view of

the user.

Somatography (Greek): sketching of bodies

In video somatography the video image of a test person is superimposed full-scale on a

drawing or a model of the workplace.

The test person can coordinate his/her movements through a control monitor (Luczak,

1998, p. 599f; Original in Martin, 1981)

Body templates exist for various body heights in front and side views as well as top view.

The indication of joint centre points allows an easy presentation of different body positions

for the verification of the design measurements of workplaces.

body templates: DIN 33408 Teil 1, also see: Pahl et al., 1996, p. 306; Pahl & Beitz, 1997,

p. 368; Luzak & Volpert, 1997, p. 382

somatography: Sanders & McCormick, 1993, pp. 419-420

physical models: Sanders & McCormick, 1993, pp. 422-423

(bottom left): Bosch Template – 4 simple templates for: 5. Perc. Female, 50. Perc.

Female/5. Perc. Male, 95. Perc, Female/50. Perc. Male, 95. Perc. Male. The rules of

technical drawings are in effect, therefore three-dimensional results in technical drawings

are also possible.

Significant simplification of the joints (point joints), but with indication of maximum angles.

(bottom right): Kiel Doll – 6 complex templates for 5., 50., 95. Perc. Female and Male. KD

available in side view for different measurements (standardised according to DIN 33408) .

Top view also available, though in practice barely used due to low practicality. Typical are

link joints for the shoulder, hip, and knee that make possible exact reaching range.

Limited applicability range since results only count for shoulder height, i.e. not movements

to the side (which is common in reality).

Today, digital human models have prevailed due to the spread of CAD. If full-scaled

CAD outputs are produced in the beginning stages into which templates are entered,

then in the digital human models body dimensions are directly taken into account in

CAD.

The human models contain databases with anthropometric measurements (body

dimensions, field of vision, joint angles, forces), a movement simulation and additional

analysis tools which make the analysis of reachability and vision, but also the

considerations of comfort, possible.

Depending on the model, two basic procedures can be derived:

1 – Model in CAD:

Here, the digital human model is integrated into the CAD environment (e.g. Anthropos

in CATIA). The geometry of the product does not first have to be exported and

transformed, rather, it is already complete and in the correct layer format. Changes

can be made directly in the primary version of the design. The advantage is that no

losses occur during the transfer of the design into other CAD environments, and

changes are integrated. A disadvantage is that a slower calculation of the CAD model

occurs which was only implemented here as a model of the CAD environment.

2 – Design analysis in the human model environment

The design is exported (partially) from the original CAD environment and then

imported into its own human model environment (with significantly less options than in

CAD). The analyses are then conducted here. The advantage is a faster calculation

(since the entire CAD environment is already running in the background). A

disadvantage, however, are problems in the transfer of the design from CAD into the

human model.

Here is an example for the general procedure of anthropometric product design

Generation of the first human model:

Basic options (left):

(1) Generation of the first representative human model via a database query

(common in human model). Important during this procedure is the relationship to the

user group, i.e. differentiation according to sex, nation, age, increase of body

dimensions, increase in height, corpulence and proportion

OR

(2) Generation of own human model based on anthropometric dimensions. The model

is hereby extrapolated and calculated through the input of a variety of different

reference dimensions.

The model along with the (simplified) product design are then presented in an

environment.

In the second step the task and the restrictions are defined:

1. The posture is determined according to inputs of the seating reference point/hip

point and the incline of the seat/backrests.

In addition, contact surfaces and the positions of the operating elements are

determined and then entered into the human model.

2. Next, the body parts and the posture (e.g. contact or gripping grasp) are

determined.

3. Finally, the animation (calculation of the posture) takes place via the human model

along with the first visual plausibility test.

“Simple” analyses such as fields of vision and spaces within reach/reachable areas

are then carried out by the model. Fields of vision are shown as cones for “outsiders”

as well as for the particular model.

Through a change in the model a plastic impression of the future view is attained.

Spaces within reach can be directly presented for the planning ergonomics, and can

thus be take into consideration by operating elements.

For ergonomics of testing the reachability of operating elements can be directly tested

by entering tasks (see previous slide). In this case the proper posture is also

accounted for.

Important: CAD environments allow for a preferred level of accuracy in such

examinations (1/10. mm are not a problem). However, the anthropometric data as

well as the posture data are not as accurate. In practice, especially for spaces within

reach or collisions with the product, safety margins of at least 1 cm should be used.

The analysis of posture comfort is more complex. Height as well as body dimensions

(these are of a general nature and independent from the product), joint angles (these

are depending on the product) and forces on the joints (details) are included in this

analysis.

By regression respectively comfort models it is possible to get a value of (dis-)comfort

out of the input values.

IMPORTANT: Do not simply follow these instructions without being critical. Instead,

check for which boundary conditions discomfort calculations were validated. Thus,

vehicle considerations (e.g. automobile manufacturing) cannot be taken over by all

areas (e.g. maintenance) without problems - particularly problematic are the

differences in posture (sitting/standing). A transfer here is impossible.

An uncritical reliance on data leads to errors!

With an individual model no user collective can be reproduced. Hence, the analyses

are to be repeated with additional models. Depending on the complexity of the

collective this may encompass more than 10 models. This is the only way that

problem areas (see slide’s head collision of large man of medium corpulence and

medium proportion) be identified and corrected.

These pictures show that the simulated movements and postures of mannequins

cannot simply be used without limitation for the design of products. Several

misinterpretations can be seen that are shown through the movement apparatus and

the theoretically allowable degrees of freedom, and which are theoretically acceptable

according to the mathematical relationships of the human model, but which cannot

actually be captured by a human.

This is especially true for the body angles or torsions and the penetration of adjacent

objects.

RAMSIS is the 3D CAD ergonomics tool. Package and design studies during the

design phase of a vehicle can be extensively processed with RAMSIS. RAMSIS is the

global leader of CAD tools for ergonomic design and analysis of vehicle interiors and

workplaces and is used by more than 60% of all automobile producers.

Advantage: Extensive analysis is already possible in the pre-production phase without

requiring building of expensive physical models. (also see Luczak & Volpert, 1997, p.

383f)

Anthropometric Database 90 real, statistically validated body types

Standard animation: Translation/rotation interactively or numerically, joint animation

numerically or interactively, fast automatic target point animation for freely definable

chains of body parts, interactive drawing of body part chains, analysis of spatial

coordinates and joint angles

Restrictive animation: Marginal posture calculations, body type independent task

description, interactive goal definition, consideration of interfaces, tangential ability

requirements, consideration of self-intersection

Health and comfort analysis: Analysis of posture comfort, posture-dependent body

part comfort evaluation, fatigue analysis, orthopaedic evaluation of spinal curvature

Vision analysis: Incorporation of eye, head and neck movements into restrictive

animation, internal sight, ergonomic evaluation of the field of vision, consideration of

focal distance, simulation of mirror view

Belt analysis: Calculation of belt routing, calculation of seatbelt points

Reachability Analysis: Body type-dependent calculations of reachability levels, (also)

for extremities, calculation of reachability surfaces for body part chains.

The human body model JACK‘s main background is in computer graphics , for

example in animation of virtual humans in movies. In anglophone countries, it is also

used for product design (primarily automotive) and as tool for educational training

movies.

Main objective of JACK today is beside of product design also the display of humans

in virtual environments. With special hardware, JACK is kind of remotely controlled

and follows the real human‘s movements. When aditionally displaying the virtual sight

of JACK, the user gets the impression of personally sitting in the vehicle. This makes

very early and detailled product analysis possible.

The database of body measurements is primarily based on US-American data sets.

They are represented as percentiles. JACK offers functionality for analysis of sight,

range, postures and movements.

Delmia (Digital Enterprise Lean Manufacturing Interactive Application) by Dassault

Systems is a software for planning, visualisation, simulation and validation for

production planning. Delmia is making first attempts to pursue the idea of digital

manufacturing and includes an integrated human model, DELMIA human.

Focus of development has been to model body measure variabilities for vehicle

interior design. Similar to RAMSIS, there an exhaustive methodology which by far

exceed simple percentile measures.

Existing analysis caapabilities comprise vision, reach, postures and movement

analysis. Additionally, there are functionalities to execute methods-time-

measurement, force and performance analysis.