ergonomics for a computer

7/23/2019 Ergonomics for a computer

http://slidepdf.com/reader/full/ergonomics-for-a-computer 1/4

r The

prototype

computer. 2

The

latestveÍsion redesigned

'l

t

I

according to ergonomic

principles.

uexen

E M I ElectronicsLtd.

'|

|

i

reset

from

one

problem

to solve

another;

easeofopera-

tion

and

avoidance

of

operator

mistakes

are therefore

essential.

Such

mistakes

are

far more

troublesome

han

loss of speedor machine inaccuracy'

A correct

setting,

but

on

a

wrong

potentiometer

-

or a switch

left

in the

wrong

position

-

can

ruin

the solution

of a

problem

and

cause

much

delay

while

the fault

is found.

Even

worse,

the

error

in the

solution

may

not be

discovered.

Therefore

the risk

of

these

mistakes

must

be reduced

to the

minimum

by

proper

attention

to ergonomlc

factors.

During

the

redesign

of EMIAC

II,

at

EMI

Elec-

tronics

Ltd,

advice

from

the

firm's

engineering

psychology laboratory

was sought

on

various

aspects

f

the operational

layout;

the

prototype, r,

was

already

fairly

satisfactory,

but

the

project

team

wished

to

make

every possible mprovement.

Ergonomics

for

a,

Gomputer

AN

ANALocuE

coMPUTER

s

an assembly

of many,

similar,

electronic

'building

bricks'

which

can

be

con-

nected

together

in a multitude

of different

ways.

The

input and output leads of the amplifiers, integrators,

and

function

potentiometers are

all brought

out sepa-

rately

to sockets

on the

'patch

panel',

which

is thus

very

similar

to a telephone

exchange

switchboard.

By

mak-

ing the

appropriate

interconnections

the operator

can

'patch

up'

the computer

to

solve

most

problems

which

can be

defined

in

suitable

mathematical

terms.

Analogue

computers

are

particularly

useful

to simu-

late

and optimize

the

design

and working

of complex

devices

with several

interdependent

variables,

such

as

suspension systems

of motor

cars

or

chemical

pro-

cessing factories

with

continuous

flow.

Flexibility

is an

important

feature

of

an analogue

computer,

so

that it can

quickly

and

accurately be

DÉSIGN

I2O



t È

ElïfIAC

I

I

panel

major

problem in this

study

was the

panel

of

z4

potent io-

all of

which

may have

to be selected

one

at a t ime

by

an

switch

and adjusted

very carefully

to an

exact

value

meter.

Unless the layout is clear and simple, there is a risk

up the

wrong

potent iometer

or of start ing

to

adiust one

already

been

set, with

consequent

annoyance

and risk

the

prototype, to economise

in space,

the

potent iometers

staggered

at

45"

to

each other

and the

jack

sockets,

through

electrical

connect ion

is

made

to the

potent iometers' were

them.

The

result

is somewhat

confusing

and there

for numbers

to

ident ify

each

iack

socket,

3.

Despite

electronic

complicat ion

and sl ight

increase

in

panel

size

it

agreed

to use

push-pull switches

with

a number on

the knob

iack

sockets;

the design

problem therefore

was to

a

layout with

which

the sequence

of operations

-

frsr,

find

the switch,

second,

frnd

the

potentiometer,

third,

it, and,

ourth,

turn off

the switch

-

would

be done

most

and

with the

least

error.

method of

tackling

this,

as with all

ergonomic

problems,

was

I2 O

f irst to

refer to

results of

all relevant

research

;

it was

found,

how-

ever,

that the

evidence

in the

literature

was

not adequate

to allow

of

reliable

extrapolat ion

to

solve the

problem.

Therefore

an

expcri-

ment2, had to be made which resulted in the optimum layout, 4.

I t was suggested

init ial ly

that

a rotary selector

switch

should

be

used

instead of

the

iack

sockets.

This

proved impract ical

electroni-

cally,

but

the discussion

and explanat ion

brought

to l ight

a way in

which

part

ofthe

basic engineering

circuit

could be

improved.

This

is

quite

a common

experience

during

ergonomic

redesign

studies;

explaining the

machine

to

someone

with

a dif ferent

specialist

approach

st imulates

the engineering

team

to reconsider

it s

system

from a fresh

viewPoint.

r See

for instance:

Applied experinental

psycholggy,,

. Chapanis'

\ í . R. Garner

and

C. T.

Mbrgan. Chapman

and

Hall

Ltd,

f,z

tz s

Hwnan

engineering

gtide

fot

equipnent

designets'

W. E.

Woodson' CUP

{ r

6s.

Data on

hunpn

perJornnnce

fot

engineeting

designers,

K.

F. H. Murrell'

reprint

from Ezgineering,

3s

Y'f

{r:if:;o,'"r;9*ÊWÍ,ïi;*h.3X'J""f

L'Y;i;.51'ïX'

H. K. Lewis & Co Ltd, dr Is .

zAnote

on

Danel

layout

for

nuntbets

of ident ical

irerts,

B, Shackel,

to be

publ ished

iÁ Ergononics.

Taylor and

Francis

Lt d

continued



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panel

Íul l

opcrat ing

sequcncc

must

bc

knorvn

belbrc

clccidirrg

rm _

panel

layouts;

only bv

analysing

thc

various

sub-rourrncs

elated

controls

bc

properly

grouped

together.

Crit ical

adjust_

and

master

controll ing

act ions

arc usuallv

made

with

th c

hand

(thc

right

hand

for

most

of the populat ion;

an d

such

conrrols

should

be

placed

casily

for

the

right

hancl,

associatcd

less

crit ical

switchcs

to

thc leÍ i.

that the

main

changc,

T

ancl

g,

u,as

to

intcrchange

Meter

F

S D switch

and

the

accuratc potcnt iometcr

with rhe

graduated

dial ;

p rev ious ly

the

opc ra to r

rvou ld

t cnd ro

opcratc

th c

metcr

switch

u' ith

thc

lelt hand,

thus

obscuring

the

meter

he

wa s

about

to read,

so as

to use

his

right

hand

Íbr

crit ical

adjustmcnt.

Thc

master

control

is

Rorv

A switch

and

is thercforc

in

thc corrccr

posit ion;

thc

ot lter

groups

of amplif iers

are

usually

undcr

it s

control,

and

thercfore

Row

B

and

Row

C switchcs

arc

in thc

less

rmportant

corncrs

of the pancl.

Other

changes

in

dctails

improvc

thc idcnt if icat ion

of su' i tch posit ions

and group

rclated

ircms

togethcr.

, t* :

"s_

ri

$eï

n*Brulf

*

r&

'-fr

)

_$t

1::'J

l

Pt}'

tt ï

{il"

RÓlV Á

Some

time

after

the

study

had

finishcd

an

opportunity

arose

to

ask

the recipient

of the prototvpe

model,

the

Hawker

Siddeley

Nuclear

Porvcr

Co

Ltd,

íor

crit ic isms

of its

operat ion.

I t rvas

pleasing,

if

not

unexpected,

to

f ind that

comments

from

at

least

three months' operat ing of the machine had all been predicted by

rhe

ergonomic

redes ign

study.

px:{

\ '

gE

brief

example

of how an

electronic

machine

is

studied

rn

o improve

the

ergonomic

aspects

of i ts

design,

only the

obvious

points

have

becn

mentioned.

To

the design

engi_

technologists,

who

are at

prcsent

the

chief users

of this

of machine, some of the more detailed aspects u, i l l be

rom

the i l lustrat ions,

ergonomics for a computer

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