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Integrated Human and Automation Systems 34.3 Design Rules for Automation 585

table shows which dialog system addresses with sense

modality.

The idea of the self-controlling vehicle has been

abandoned. Although technical control systems are gen-

erally available, public opinion has determined that

the driver is responsible for driving and not the lane

control or tailgate protection system. Possible legal con-

sequences in the case of failure of the technology are

difﬁcult to assess.

The application area of aviation is traditionally

characterized by progressive technologies. As a result,

many assisting systems exist in the ﬁeld. Table 34.3

presents an assistant type and the used modality for

some assisting functions in a plane.

On the level of plane stabilization, we ﬁnd in-

tervening systems, including maneuver delimiter and

commanding systems such as light vector displays,

a stick-shaker, and callouts. Steering is supported by

collision-prevention commands and ground-proximity

warnings.

For the planning of the ﬂight path, the ﬂight

management system is supported by an informational

system that leads the pilot from the start to the

destination via previously entered travel points. The

electronically centralized aircraft monitoring (ECAM)

system is a consultation system that supports the pilot

actively when managing system resources and correct-

ing errors. Error messages are determined by individual

phases of the ﬂight. Furthermore, a plan possesses

dialog systems through which the pilot executes the

ﬂight path, the management of subsystems, and the

management of errors. More assisting systems concern

information exchange withair-trafﬁc control, communi-

cation with the operating airline (company regulations),

and execution of braking maneuvers on the runway

(break-to-vacate).

34.3 Design Rules for Automation

The design of automated work systems are usually

geared to systematic work design. It is subject to spe-

ciﬁc requirements and methods, whichwill bepresented

below.

34.3.1 Goal System for Work Design

The decision for a speciﬁc kind of design of a work sys-

tem – including the option of automation – is mainly

determined by the following three goals [34.35]:

1. Functional goals:Optimal accomplishment of func-

tions (for example, dependability, endurance, pre-

cision, and reproduction). The limited capabilities

of man regarding sensors (for example, no adequate

receptors for voltage, operations being fast, objects

being small) or motor functions (for example, re-

garding the height and endurance of body power)

often demand the use of technologies. Man’s broad

capabilities and ﬂexibility, which allows him to di-

verge, if necessary, from ﬁxed algorithms and to

react to changed situations, demand the inclusion of

a human being [34.36].

2. Human-oriented goals: Goals that concern human

health, as well as performance prerequisites (for

example, work safety, level of task demands, and

qualiﬁcation).

3. Economic goals: Given function fulﬁllment with

preferably low costs, or best function fulﬁllment

with ﬁxed costs.

It is not possible to derive a priority for a single design

goal in the goal system, as usually one has to choose

an optimum between opposing subgoals. In individ-

ual cases anthropocentric or technocentric approaches

of design result from the emphasis of different goals.

Here, we favor a anthropocentric (that is to say, human-

oriented) approach to design.

34.3.2 Approach to the Development

and Design of Automated Systems

Consideration of Life Cycles

The development of a man–machine system oc-

curs based on a formalized plan. The development

of a system is subdivided into individual phases

(Fig.34.10):

•

The process of development and design begins with

a prerun phase, during which a system concept is

processed. This phase aims to identify the current

problem, and to evaluate whether it is really nec-

essary to build the intended system and where it

should be used.

Part D 34.3

586 Part D Automation Design: Theory and Methods for Integration

•

During the deﬁnition phase, the system is decon-

structed into subfunctions and subsystems. Speciﬁ-

cations are developed, in which all characteristics

and performance features as well as demands for

man and technology have to be included. Perfor-

mance is related to the system’s different phases of

use, e.g., operation and maintenance [34.37]. With

regard to the predetermined aspects, the layout and

evaluation of alternative solutions are developed for

each subsystem.

•

During the development phase, a detailed design of

the subsystem’s hardware and software is realized.

The developed solutions are integrated into a com-

plete functional system.

•

The acquisition phase comprises production of

the system’s hard- and software, testing of the

technical subsystem’s functionality, integration of

mechanical components, and production of user and

maintenance instructions. Furthermore, staff will be

included in this phase.

•

During the use phase, usage of the system is

realized. Operational experiences, which include

a normal, disturbed, and maintained operation, form

the basis for improvement, modernization, and re-

design of similar systems.

A review at the end of each phase decides upon the start

of the next phase, when the development project has

achieved a deﬁnite level of maturity.

Design Projects

The following design projects are exercised for each

phase of a man–machine system (Fig.34.9)

•

With the help of system analysis the general goals

for the complete system are determined, then the

problem is ﬁrmly established and detailed.

Forerunner

phase

Task analyses Evaluation

Technological/technical/

organizational/ergonomical

design

Definition

phase

Developing

phase

Aquisition

phase

Utilization

phase

Fig. 34.10 Phases of an automated system and their development project

•

Within the framework of the function analysis,the

system functions necessary to achieve the prede-

termined goals are established. The analyses of

individual functions and their allocation to the ma-

chine or to man is the task of the technological work

design.

•

The tasks for the human result from the assign-

ment of functions. Through a task analysis we have

to evaluate whether the function and its related

task can generally be conducted by the available

staff. A group of users has to be selected and

trained.

•

Technical, organizational, and ergonomic work de-

sign aims for optimal development of the system

components and work conditions through alignment

of the conditions to the user (Sect.34.1.1).

•

An evaluation helps to verify the efﬁciency of the

enforced design measurements for the implemented

system. In order to achieve system optimization, the

design methods have to be adjusted in case of goal

divergence.

Emphasis on Human-Oriented Design

Within the realm of the human-oriented design of

a man–machine system, the functions and components

with a high degree of interaction between men and ma-

chine [34.38] are the most important. When designing

partly automated systems or assisting systems, the fol-

lowing tasks are mainly affected:

•

Tasks for function division between man and ma-

chine as well as for structuringthe task given to man

(i.e., technical/technologicalor organizational work

design)

•

Tasks for optimization of integration of communi-

cation at the interface of man and machine (i. e.,

ergonomic design)

Part D 34.3

Integrated Human and Automation Systems 34.3 Design Rules for Automation 587

•

Tasks to increase job or machine safety (i.e., tech-

nical design) by including hazardous factors of the

work environment (e.g., noise, climate, vibrations).

Task-speciﬁc criteria and requirements of human-

oriented work design as well as methodical approaches

will be discussed in the following sections.

34.3.3 Function Division

and Work Structuring

Subfunctions of a work system can be achieved by man

and bya machine.If man is the center of interest,the de-

sign of the work system is geared towards the following

levels of evaluation of human work [34.39]:

•

Feasibility: anthropometrical, psychophysical, bio-

mechanical thresholds for brief workload duration

in order to prevent health damage

•

Tolerability: physiological and medical thresholds

for a long workload duration

•

Reasonability: sociological, group speciﬁc, and in-

dividual thresholds for a long workload duration

•

Satisfaction: individual sociopsychological thresh-

olds with long and short validity.

In manual assembly, for example the joining of parts,

certain thresholds result for the worker due to the re-

quired speed or accuracy of motions. Figure 34.11

presents this situation schematically.

Ergonomic optimization is desirable, if the com-

bination of stress parameters resulting from the work

task leads to tolerable work conditions (i.e., ergonomic

Satis-

fied?

Precision of movement

Speed of movement

Reasonable?

Automation

not possible

Ergonomical design

achievable and tolerable

Work structuring

achievable, not tolerable

Fig. 34.11 Dimensions of work design from an ergonomic

point of view [34.4]

design, see Sect. 34.1.1). If work can be done but

is not tolerable, mainly the content of the working

task has to be changed with the help of measure-

ments regarding work structuring (i. e., organizational

design, see Sect. 34.1.1). If the work task cannot be

fulﬁlled, automation (i.e., a technical/technological

design, see Sect.34.1.1) of the work system is recom-

mended, which implies extensive transfer of functions

to a machine.

Further inﬂuences on the design of systems result

from technical and economical requirements. Due to

the numerous inﬂuences on the design, it is impossi-

ble to distinguish speciﬁc design dimensions from each

other. In factories we can ﬁnd work systems with dif-

ferent degrees of automation among which are obvious

combinations of manual and automated systems (hybrid

systems).

When assigning functions within the man–machine

system,thepsychologicalandphysiologicalperformance

requirements of the working man have to be taken into

consideration (Sect.34.1.8). In this way overextension

of the worker can be avoided and health damage can

be averted. Appropriate work structuring also takes into

consideration not giving the man solely leftover func-

tions, where he compensates or conducts nonautomated

functions. Function division and work structuring there-

fore have to be developed in such a way that interesting,

motivating, and diversiﬁed task arise [34.40] and opti-

mal system effectiveness is guaranteed.

34.3.4 Designing a Man–Machine Interface

A central task when developing human-oriented auto-

mated work systems is the design of the man–machine

interface. Ergonomically designed workplaces and ma-

chines – both in regard to hardware and software with

the corresponding desktop – contribute to user-friendly

and efﬁcient task accomplishment.

Workplace

The workplace is the place where the task will be ac-

complished. At workplaces on the production level the

following problems often occur:

•

Inappropriate posture, forced posture due to limited

free space or awkward positioning of appliances

•

One-sided, repetitive movements

•

Inappropriate movement of arms and legs

•

Appliance of body forces.

In terms of ergonomic work design the demand arises to

adjust the workplace in regard to its dimensions, visual

Part D 34.3

588 Part D Automation Design: Theory and Methods for Integration

and active area, and the forces that have to be applied

to the conditions of the working man. The starting point

for workplace design is the working task. Depending

on the working task, speciﬁc demands arise in regard

to motor functions and visual perception. The demands

of the working task have to match man’s performance

prerequisites. Figure 34.12 showsfactorsthathaveto

be taken into consideration when designing a work-

place. The technologies or materials that are used can

lead to further demands in regard to the conﬁguration

of the workplace, for example, lighting, ventilation, and

storage.

Anthropometric Design of Workplaces. The starting

point for anthropometric design of workplaces is the

size of the human body. In order to prevent forced

posture, e.g., intense bending forward or to the side,

workplaces have to be aligned with the body size of the

workers who work at that particular place.

When discussing the anthropometric design of the

workplace, it has to be clariﬁed whether work will take

place sitting or standing (Fig. 34.13). A balanced posi-

tion can be achieved by a change of posture. Basically

it is important to set the human body size in relation to

the correct distance between ﬂoor or feet height, work-

ing height, and seat height. The working height has to

be adjusted to the conditions of the work task. In ad-

dition it is important to have sufﬁcient horizontal and

vertical space.

If severalpersons work at different times at the same

workplace (for example, shift work), the workplace has

to be equipped with appropriate adjustability in order to

be adjusted to different body shapes and heights.

Physiological Design of Workplaces. Physical strength

also has to be taken into consideration at automated

Human

One person / collective

Gender, age, nationality

Capabilities

Working task

Movement, force,

preciseness, frequency

Working tool

component

Work-

place

Sitting / standing

Order and measurement

of tools

Dimensions

(visual and active space)

climate, sound

Fig. 34.12 Factors for the design of

a workplace

a: height of

working space

b: height of the seat

e: distance of

working place

s: visual distance

α: foot rest incline

t: floor space depth

Fig. 34.13 Blueprint of a possible seat-standing workplace

workplaces, as the basis for lifting and carrying of loads

and operation of the system elements. Tasks that require

intensive body movements and a large amount of physi-

cal strength should be conducted in a standing position.

Tasks that require a high degree of preciseness (e.g.,

subtle assembly) and little physical strength can be con-

ducted while sitting. Information about the dimensions

of working tasks and their required physical strength is

given in ergonomic literature [34.1,5,41].

Anatomically Favorable Alignment of Working Tools.

Anatomically favorable alignment of appliances and

working tools avoids unnecessary movement and as-

sists balanced physical strain on the human body.

Figure 34.14 presents an example of how to align ap-

pliances in a partly automated workplace. Objects that

have to be grasped (bin with parts) are arranged within

Part D 34.3

Integrated Human and Automation Systems 34.3 Design Rules for Automation 589

Fig. 34.14 Partly automated manufacturing workplace

a reachable distance and the machine is positioned in

the center.

Design of VDU Workplaces. Most of the time automated

work in an ofﬁce is performed at visual display units

(VDUs). In addition to the working postures already

mentioned above, the following factors have to be taken

into account when working at a VDU [34.43]:

•

Strain of the supporting apparatus or musculoskele-

tal system: Continuous, static sitting strains the

supporting apparatus and the musculoskeletal sys-

tem extremely and can lead to muscle tensions and

degeneration effects. Repetitive tasks such as data

entry can lead to pain in the wrist (for example,

repetitive strain injury) and chronic back pain.

•

Eyestrain: Frequent change of eye contact between

screen, draft, and keyboard (that is to say, accommo-

dation) and the resulting adjustment to the changing

light level (that is to say, adaptation) provoke enor-

mous strain on the eyes and can cause eye damage.

•

Psycho-mental strain: Man is stressed while carry-

ing out demanding informational tasks when being

exposed to (unintentional) interruptions, time pres-

sure, and fragmentation of the work task.

The demand to conﬁgure the daily work schedule with

a change of activities or regular breaks is very im-

portant for the human-oriented design of a workplace.

VDU tasks and other activities should be alternated

in order to avoid burden on the eyes and encourage

movement. If a change of activity cannot be realized,

regularly short breaks from work at the screen should

be included [34.27].

Man–Machine Communication

In the course of automation, interaction between man

and machine becomes an information exchange, i.e.,

man–machine communication. This information ex-

change is realized by man’s sensors (i.e., senses) and

actuating elements (i. e., effectors) on the one hand,

and input and display systems of the machine on the

other. This exchange of information is controlled by

the human or technical processing of the information.

Software ergonomic work design has the function of

designing input and display systems and the machine’s

processing of information according to ergonomic goals

(Sect.34.3.3). While so doing, the task and conditions

of the working environment are taken into account. Ad-

ditional tasks result from the selection and education of

users who operate these systems.

Sensory, cognitive, and motor characteristics have

to be taken into account when designing man–machine

communication. The visual channel (the eye) can be ad-

dressed via optical displays, the auditory channel (the

ear) via acoustic displays, and the tactile channel (sense

of touch) via haptic displays. As the hand and foot mo-

tor functions are available for the mechanical input after

processing of information by the brain (cognition), so

language is available for linguistic input. Now input

via body movement (gestures) also plays an impor-

tant role, for example, through the use of the mouse

or via the measurement of hand, head, and eye move-

ment (movement tracking). According to Fig.34.15,the

Processing of information

Dialogue control

Sensors Actuating elements

Display system Input system

Input and

display systems

Dialogue system

Assisting system

User modeling

Task modeling

Situation identification

Risk analysis

Technical functions

Man

Machine

Fig. 34.15 Levels of man–machine communication [34.42]

Part D 34.3

590 Part D Automation Design: Theory and Methods for Integration

design of man–machine communication can be repre-

sented at three levels:

•

The highest level shows the interface between man

and machine, the input and display systems, which

are often deﬁned as the desktop.

•

The next level is the dialogue system, which creates

the connection between the input and display, and

which causes the machine’s control of information

ﬂow.

•

The third level refers to the application of assisting

systems, which support the user when developing

processing strategies and system control.

The design of these levels has the goal of tuning the

technical system for the acceptance, processing, and

display of information for man and his tasks.

Input and Display Systems. The design of an input and

display system has to resolve three tasks [34.44]:

•

It has to choose appropriate design parameters ac-

cording to human conditions when adjusting the

system to the human’s motor function and sensors.

•

It has to display the information codes that are nec-

essary for exchange of information between man

and machine; in this case, compatibility has to be

taken into account.

•

The organization of information designs the input or

output of connected information.

Appropriate input systems are those that use human ca-

pabilities for the transmission of information: exercise

of body force on objects, gestures, mimics, talking, and

writing. Technical input systems are also useful if they

can absorb and interpret the provided information. The

best available technology allows the extended utiliza-

tion of the previously mentioned human capabilities by

using switches, levers, hand wheels, dials, keys, key-

boards (for example, work at the VDU), etc. Speech

recognition systems have seen immense progress, so

that the use of speech signal input can be realized, for

example, when entering numeric codes. Writinginput is

used with electronic notebooks.

When releasing information, visual, auditory, and

tactile kinesthetic sense modalities are addressed. Fur-

thermore, speech output is becoming increasingly

important. Haptic displays are mainly used to facili-

tate blind operation of switches. Due to the amount and

variability of the presented information and the optional

access options, optical displays – mostly in the form of

screens – play a dominant role. Multimedia forms of

communication connect the different forms of coding:

number, text, speech, and picture.

Compatibility of the design of (complex) input and

output display systems is extremely important. Com-

patibility can also be deﬁned as the decoding process,

which the human has to achieve when evaluating the

different forms of information. Inner compatibility is

achieved when compatibility exists between man’s pe-

riphery and the inner models (i.e., associations and

stereotypes). A good example is the fact that one ex-

pects an increase in value when turning the adjusting

knob to the right. An outer compatibility is in place

when a display turns to the right according to the move-

ment of the operating element.

Dialogue Systems. Dialogue represents the interactive

exchange of information between man and machine

in order to achieve a task. Depending on the user’s

previous knowledge, different dialogue forms are pos-

sible: question–answer dialogue, form dialogue, menu

dialogue, key dialogue, command dialogue, and natu-

ral conversational dialogue. Dialogue forms as well as

a direct manipulation comprise concrete actions (for

example, display or sketching), pictures, and speech.

These demand less abstraction from the user than

text-based dialogues. There is always the possibil-

ity to adjust the dialogue system to a user-speciﬁc

demand.

Continuous technical progress leads to rapid in-

troduction of new program versions with dialogue

alternatives. In order to guarantee reliable utilization,

the user has to learn continuously. As printed instruc-

tion sheets are often ignored, integrated guidance of the

user in the dialogue is practical. This guidance should

be in line with the user’s learning progress and the as-

sisting and support systems, which the user can use in

the dialogue.

Assisting Systems. Man–machine communication is

generally designed as a dialogue, i.e., interaction be-

tween information input and output. Assisting systems

(or dialogue assistants) support the user during goal-

oriented use of a dialogue system by explaining the

system’s functions and user directions (Sect. 34.1.7). In

order to guarantee progress of the dialogue, datais taken

from the user (that is to say, user modeling), from the

task to be solved (that is to say, task modeling), and

from the present state of the system (that is to say,

situation identiﬁcation). In so doing, the ﬁeld of man–

machine communication comprises increasingly higher

levels of technical processing of information. Whereas

Part D 34.3

Integrated Human and Automation Systems 34.3 Design Rules for Automation 591

at the beginning only the desktop was affected in the

form of display and input elements, nowadays the entire

design of informational–technical systems are directed

to the user.

Principles of Design

for Man–Machine Communication

The design of man–machine communication mainly

comprises aspects of dialogue development and control

hierarchy.

Dialogue Development. Software ergonomic develop-

ment of man–machine communication is geared to-

wards the following demands for appropriate dialogue

development [34.45]:

•

Usability characterizes the degree to which a prod-

uct can be used effective, efﬁciently, and in a satis-

fying way.

•

Effectiveness determines the precision and com-

pleteness with which the user can achieve a certain

task goal. Errors can have a negative impact on

effectiveness. This is the case when the user is in-

capable of achieving the deﬁned goal correctly or

completely.

•

Efﬁciency describes the cost-related effectiveness,

referring to the relation between the achieved pre-

cision and completeness of the effort used by the

user while attaining the goal. Deﬁciencies affect ef-

ﬁciency of utilization (ﬁtness for use). The result is

correct, but the effort is inappropriate, as the user,

for example, can hardly avoid making mistakes.

•

Satisfaction is an indicator of the acceptance of uti-

lization.

Dialogue design

Functionality

(suitability for the task)

Usability

(suitability for learning)

Manipulation

Suitability for

individualization

Controllability

Orientation

ClearnessError toleranceCompatibility

Self-

descriptiveness

Fig. 34.16 Design principles of the

ISO 9241 standard for man–machine

communication

Central criteria for dialogue design are functionality

(i.e., the suitability of the task) and usability (i. e.,

suitability for learning). The ISO 9241 standard [34.3]

deﬁnes established principles for the design of man–

machine communication (Fig.34.16):

•

Suitability for the task: While working, the user

should experience support instead of interference or

unnecessary demands.

•

Self-descriptiveness: The dialogue should make it

clear what the user should do next.

•

Controllability: The user should be able to control

the pace and sequence of the interaction.

•

Compatibility, conformity with user expectations:

General experiences, schooling, experiences with

work processes or similar software are effectively

applicable. In terms of the expectation conformity,

boundaries of the technical system have to be trans-

parent (for example, safety functions).

•

Error tolerance: The dialogue should be forgiving.

In spite ofdefective input, theresult will beachieved

with only a few corrections.

•

Suitability for individualization: The dialogue sys-

tem allows adjustments to the demands of the

working task, to the user’s individual preferences,

and to the utilization capability.

•

Suitability for learning: The user will be supported

and instructed while learning the dialogue system.

Burmester [34.46] recommends a simple and clear

presentation of information, direct and unambiguous

language, direct feedback, as well as user-oriented ter-

minology for the implementation of design principles.

In order to design the utilization capability of the man–

Part D 34.3

592 Part D Automation Design: Theory and Methods for Integration

machine system more intuitively, known objects, for

example, ofﬁce folders, are displayed on the software’s

desktop.

Control Hierarchy. The embedding of the dialogue sys-

tem intothe control hierarchy of a man–machine system

is as important as the dialogue design itself. Here we

have to clarify, if and how far the technical system is

allowed to limit man’s freedom to take decisions and

carry out actions. This question can be illustrated with

the help of the example of a driving assisting system,

which leads to increased safety for the driver when

maintaining an inappropriate distance to the preceding

vehicle and a reduction in speed.

Man’s capability to make a decision is dependent on

his position in the MMS. Decker [34.47] classiﬁes three

different performance types:

•

Restitution performances: Here, the machine en-

ables a disabled human being to achieve standard

performances. Examples are prosthesis for ampu-

tated body limbs.

•

Expansion performances: Here, man achieves to-

gether with the machine a higher level of per-

formance than a standard performance. A good

example is a databank system, which simpliﬁes the

data management and data organization.

•

Substitutionperformances: The performance,which

so far has been accomplished by man, is now

achieved by a machine supervised by man. An ex-

ample is the autopilot in a plane.

Experts are of the opinion that, as long as it is not pos-

sible to completely substitute man by a machine, man

should have the highest level of decision making in

a man–machine environment [34.48]. This implies that

man will have the ﬁnal decision. In this way, man can

correct the MMS in case of errors.

The following problem appears however with partly

automated MMS: During long working phases of un-

interrupted automated production, man is permanently

unchallenged and easily fatigued. If man then actually

has to interfere due to a breakdown of the automated

system, the once unchallenging situations transforms

into a too challenging one. Consequently, we should

aim for a continuous activity level, in order to guarantee

manual takeover of the controlling system. Moreover,

redundancy should assure that the entire system is

reliable.

34.3.5 Increase of Occupational Safety

Automation of working systems needs to take into

account occupational safety. Occupational safety is

a necessary requirement for work processing. Safe

working conditions should minimize or even prevent

health damage to the working man. Generally speak-

ing, the work result cannot be guaranteed if unsafe work

conditions exist. A high level of safety is guaranteed

by measures of machine safety. Occupational safety

comprises safety measures and rules of conduct, which

should provide the user of technical systems with the

highest protection possible.

Automation measures basically reduce the haz-

ardous risks to the worker. However, when breakdowns

occur, the untrained worker has to interfere under time

pressure, which can cause new danger situations.

The design of a man–machine interface with an ab-

stract representation of information between user and

system, and that also screens mechanical noises and

vibrations, results in the risk that man’s contact with

reality is weakened. It has been observed that some

drivers compensate for safety gained through assisting

systems by changing to a risky driving style [34.49]. As

a result we can state that the demand for increased oc-

cupational safety always has to be seen in the context of

system reliability.

System Reliability

The term system reliability deﬁnes the probability that

the system works without any errors in a deﬁned

timeframe. An error can be deﬁned as an intolerable

divergence from a deﬁned level of quality. Human re-

liability describes man’s capability to accomplish a task

in an acceptable way under ﬁxed conditions within

a deﬁned time frame. Here a basic difference between

human and technical reliability becomes visible: man

works in a goal-oriented manner, whereas the machine

works in a functional way. Man is able to control his

actions autonomously. Human errors do not usually

lead to an immediate breakdown, but can be corrected

before they negatively affect system operations. The

technical design of systems should assure the reliabil-

ity of the machine and its components through optimal

construction and selection of appropriate materials. Hu-

man reliability can be increased by rapid identiﬁcation

of errors by the technical system and a supporting

decision-making process. Man is able to recognize and

correct for his own errors prior to their interference with

Part D 34.3

Integrated Human and Automation Systems 34.3 Design Rules for Automation 593

the system. He can also stop processes that seem to be

becoming problematic [34.50].

Design for Safety

Design Strategies. Adequate actions can contribute to

an increase in the safety level of automated working

systems and minimization of hazardous risks. The fol-

lowing kinds of risks have to be taken into account:

•

Hazardous risks linked to theutilization of thework-

ing tool

•

Hazardous risks that emerge at the workplace due to

interaction of the working tools with each other

•

Hazardous risks caused by the working materials or

the working environment.

Here we have to conduct a risk analysis of the work-

ing tool at the predetermined workplace. We have to set

this analysis in relation to other working mediums and

take all operating conditions (i.e., normal mode, mal-

function mode, and reconnection) into consideration.

The following rules have to be followed when de-

signing for safety [34.43]:

•

Elimination or minimization of hazardous risks

(i.e., indirect measures, for example, integration of

a safety concept when developing or constructing

a machine)

•

Implementing safety measures against risks that

cannot be eliminated (i.e., indirect measures)

•

Supply of information to users about remaining

risks due to the incomplete effectiveness of the im-

plemented safety measures; indication of eventual

Fig. 34.17 Disjunctive safety device at a palletizing

automaton

necessary special training and personal protection

equipment (i.e., information measures).

Risk Minimization of Mechanical Hazards. Mechan-

ical hazards are, for example, objects that fall or slide

out, dangerous surfaces and forms, moveable parts,

instability or material failure. Appropriate protective

measures have to been chosen for risk minimization of

mechanical hazards. Here we have to differentiate be-

tween inherently safe construction and technical safety

measures.

Inherently safe construction minimizes or elimi-

nates risks through an adequate design. Examples of

inherently safe constructions are the following:

•

Avoidance of sharp edges

•

Consideration of geometric and physicalfactors (for

example, limitation of amount, speed, energy, and

noise)

•

Electrical supply of energy at extra-low voltage.

Technical safety measures should be used when the in-

herently safe constructions are not sufﬁcient enough.

Technical safety measures differ between disjunctive

and nondisjunctive appliances [34.51].

A separating safety device is part of a machine

which is used as a special kind of bodily shield

(Fig.34.17). Depending on its construction, a separat-

ing safety measure can be a cabinet, cover, shield, door,

casing, etc. The following two devices are examples of

separating safety devices [34.40]:

•

Fixed separating safety device: Theseare eitherlast-

ing (for example welded) or ﬁxed to the machine

with thehelp ofelements (for example, abolt). They

block access to a dangerous area.

•

Movable separating safety device: These are mostly

mechanical in nature and connected to the machine

(by hinges, for example). They can be opened even

without the utilization of tools. A touch-sensitive

switch prevents the execution of dangerous machine

functions while the safety device is open.

The physical barrier between man and the hazardous

machine function is absent in the case of a nonsepa-

rating safety device. The worker will be recognized as

soon as he enters or reaches into the danger area. As

soon as the worker is recognized, the existing risk is

minimized or eliminated. We can differentiate between

the following nonseparable safety devices:

•

Control device with automatic reset device: Control

devicesthat start and maintain operation of mechan-

Part D 34.3

594 Part D Automation Design: Theory and Methods for Integration

Fig. 34.18 Safety measure with approximation function

(light barrier) at a partly automated assembly area

ical parts only as long as a hand control or operating

element is actuated. Examples are hand drills and an

edge grinder:

•

Two-hand coupling: Control devices that demands

the use of both hands at the same time in order to

start or maintain the machine’s functions.

•

Protective device with approximation function: De-

vices that stop hazardous mechanical parts as soon

as a person or a part of the human body crosses

a well-deﬁned boundary (for example, light barrier,

see Fig.34.18).

Man–Machine Interface. Switches for the operation

mode and the removal of the energy supply are ap-

plied when designing a safe man–machine-interface

(Sect.34.1.3). Consequently, we ﬁnd the following spe-

ciﬁc design features:

•

Switch for operation mode: Machines have to be re-

liably stopped in all functions or safety levels (for

example, maintenance, inspection).

•

Energy supply: The spontaneous restart of a ma-

chine after a breakdown of energy supply has to be

avoided, if this implies danger to the worker.

When designing a man–machine interface for safety,

displays have to be adjusted to human perceptive senses

so that relevant signals, warnings or information can

be quickly and reliably noticed. In order to evaluate

a situation, man allocates the role of key elements

to a multiplicity of sensations. These key elements

are incorporated into superior strategies. If complex

information is arranged in functional groups, decision-

making processes will be accomplished in a better way.

Man, for example, recognizes qualitative changes of

process parameters faster and is also able to assess them

better if they are presented in graphical patterns. The

combination of graphical elements producesa pattern in

which changes can be recognizedright away. In the case

of a change in the pattern, man can selectively change

to the next deeper level of information processing, in

which detailed information about the situationand other

characteristics relevant to the decision such as quantita-

tive measures is available. A superior graphical model

functions as an early warning system.

34.4 Emerging Trends and Prospects for Automation

34.4.1 Innovative Systems

and Their Application

In the light of technical innovation it can be expected

that automation of the value-creation processes will in-

crease in all branches and application areas. When used

adequately, automation can contribute to the improve-

ment of product quality, the increase of productivity,

and the enhancement of quality of work [34.52]. With-

out automation technology, some ﬁelds of human work

would not be accomplishable. Theoperation ofcomplex

control systems in modern aircrafts may exemplify this

circumstance.

With thehelp of efﬁcient methods and procedures of

automation technology, new systems and products can

be obtained. Flexible automation, rather then the high-

est degree of automation, is the aim. Characteristics of

these systems and products are increasing complexity

and decentralization, a higher degree of cross-linking,

and dynamic behavior. However, they are only control-

lable with the help of automated appliances. Example

products can be found in the ﬁeld of mechatronics. As

well as in the traditional application areas in the ﬁeld

of process and production automation, automated solu-

tions are also frequently used in the service industries,

maintenance areas, and the ﬁeld of leisure activities

Part D 34.4