Designing the Human Machine Interface of Innovative

Emergency Handling Systems in Cars

M anfred D A N G E L M A IE R * and P etra M A N G O L **

*F raunhofer IA O , N obelstr. 12, D -70569 S tuttgart,

**IA T , N obelstr. 12, D -70569 S tuttgart

P R O B L E M S O F T H E H M I D E SIG N

In the E uropean T ransport T elem atics p ro jec t SA V E, a "system for the effective assessm ent

o f the d river sta te con tro l and vehicle contro l in em ergency situations" is being developed.

C om ponents o f this type o f innovative em ergency handling system s are under developm ent

since several years includ ing especially d river m onitoring and w arn ing (B rookhuis 1991,

K aneda 1994, K atahara 1995, W ierw ille W .W . 1993, 1994), and au tom atic d riv ing capab ili­

ties (C arre ra 1995, N aab 1995). T he hum an m achine interface (H M I) o f the in teg ra ted sys­

tem s are related w ith specific and partly new problem s concerning traffic safety on the one

hand and the eng ineering process in the developm ent on the o ther hand.

C oncerning traffic safety it can be said that the hum an m achine in terface (H M I) o f such type

o f system s is unobtrusive under norm al driv ing conditions. T here is no necessity fo r any hu ­

m an m achine d ialogue. T he system can be easily activated together w ith the engine. T he

driver sta te con tro l subsystem and the related rou tines w ill run in the background. T he driver

w ill not be aw are o f the system under norm al driv ing conditions. O nly if an im paired d river

sta te is detected by the d river m onitoring system a hum an m achine in teraction m igh t be re ­

quired. In th is case the boundary cond itions fo r the d ialogue are w orst. T he d river is in an

im paired state and her/h is perform ance is m ost p robably restricted , bo th fo r the in teraction

w ith the em ergency handling system and for driv ing . T he ability to d rive safely is therefore

decreased. T he d river should thus concen trate on the basic driv ing functions and on the traffic

situation. B ut in addition the hum an m achine d ialogue is requ ired , w hich again m ay effect

traffic safety negatively . T h is m eans that there m ight be the risk that those innovative system s

can be counterproductive in certain situations.

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T o go m ore in to detail five d ifferen t princip le cases and related p rob lem s can be d istin ­

guished:

1. N orm al driv ing conditions do not require any hum an m achine d ialogue. T here w ill be som e

basic system state inform ation d isplayed for the driver, w hich needs n o t to be read regu larly .

2. T here is an em ergency detected by the em ergency system in the surrounding traffic v ia car-

to -car com m unication . T hen the d river is not in an im paired sta te and therefo re able to p er­

fo rm in an appropriate w ay. B ut if the em ergency in surrounding traffic is located nearby

ahead the d river has to turn attention to the traffic situation. T here is a risk that a w arn ing

m essage by the system m ight d istract the drivers attention from the road scene.

3. T he d river m onito ring system detects an im paired but non-critical d river state. T hen the

system has to w arn the d river and m ake her/h im to react properly . T here m ight be also a h igh

inform ation flow to the d river under adverse conditions.

4. T he d river m onito ring system detects an uncertain d river state. T h is is the m ost critical phase

fo r the hum an m achine interaction. T he system has to decide quick ly by com m unication w ith

the d river w hether to take contro l over the car o r to leave the con tro l to the driver. T h erefo re

there is not only an inform ation output to the d river requ ired , w hich needs to be understood

b u t also a d river reaction. T his m eans an inform ation input by the d river to the system , w hich

she/he m igh t have never perform ed before and all th is in a probab ly critical personal situation

o f the d river and an evo lv ing critical traffic situation.

5. T he driver m onito ring system detects a critical d river state. T hen the au tom atic em ergency

handling functions w ill be initiated, e. g. an em ergency call w ill be sent to an em ergency

centre and the car w ill be stopped autom atically . T his situation is h ighly dem anding fo r the

technical system s but it is less critical for the influence o f the H M I design on driv ing safety as

the d river is suspended from driving.

B esides traffic safety considerations the design process itse lf is an im portan t issue. T h e H M I

as a safety re levan t subsystem has to be considered early in the design process. H M I concep ts

have to be evaluated by users as soon as possib le in o rder to de liver re levan t input fo r fu rther

design decisions for the w hole system . T he H M I has to be developed in paralle l w ith the de­

velopm ent o f the new system technologies for d river m onitoring , au tom atic em ergency h an d ­

ling and com m unication . T his results in uncertain ty concern ing the design o f o ther techn ical

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subsystem s, w hich m eans that the H M I design has to start on the basis o f assum ptions. T his

m eans sim u ltaneous eng ineering is in dem and and rapid pro to typ ing m ethods are required .

A P P R O A C H F O R T H E H M I D E SIG N

Figure 1 show s the basic approach chosen fo r the design o f the H M I o f the S A V E system .

F igu re 1 : D esign process fo r the H M I o f the S A V E system

Formulate basic design principles for the HMI

Create verbal scenarios of• external boundary conditions (e. g. market development)• internal boundary conditions (e. g. results o f technical

developments in the project)• key design characteristics of the HMI

Specify HMI functions

Conceptualise and visualise the HMI on paper and with a rapid prototyping Tool

Build rapid prototyping computer simulation of HMI

Perform user tests

Build mock-up and integrate in sim ulator

Perform user tests

Build demonstrator car

Perform user tests

- s ,Modify demonstrator car

A s a basis fo r the defin ition o f the H M I, design princip les are form ulated , in o rder to help the

H M I designers o f the SA V E device. T hey show the basic philosophy o f the in terface design

ra ther than p re-se tting design decisions.. T he design princip les are based on general princip les

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o f the design o f H M Is in vehicles. T hey take the basic functions and objectives o f the SA V E

dev ice in to consideration .

SA V E H M I scenarios are developed in o rder to achieve a com m on understand ing o f the H M I

w ith in the pro ject team s in an early phase o f the project. E xternal factors and developm ents,

e.g. m arket trends in car design and available telem atic infrastructures are considered as well

as in ternal factors, w hich are related to further results o f the S A V E project to fo rm scenarios

o f boundary conditions o f the H M I design. T hose env ironm ental scenarios are used to form

basic scenarios o f the key design characteristics o f the HM I. S cenarios are pre-selected by the

consortium for fu rther elaboration o f the corresponding H M I design.

In the next steps a functional specification is perform ed. T he results are used as input fo r the

concep tualisation o f the H M I design. F irst drafts are v isualised on paper as w ell as w ith a

rap id pro to typ ing tool. T h is tool is also used to create com puter sim ulation o f alternative de­

sign concepts, a llow ing fo r dem onstration as well as for user tests o f the hum an-m achine in ­

teraction under non-driv ing conditions. T he pointing device o f the com puter is used during

those user tests. U ser acceptance o f concepts and som e aspects o f the user d ialogue can be

tested. A s the m anipu lation and spatial arrangem ent o f d isplays and con tro ls is not realistic,

fu rther user tests are required.

F or this purpose a m ock-up o f one o f the selected alternatives is bu ilt first and then in tegrated

in driv ing sim ulators fo r fu rther testing. D riv ing sim ulators can o ffer a realistic driv ing task

and realistic spatial arrangem ent and m anipulation o f d isplays and controls. T his is necessary

to test an thropom etric and biom echanic aspects o f the design. E ven m ore im portan t is the test

o f the in teraction o f the prim ary driv ing task and the d ialogue betw een the the d river and the

em ergency handling system . Those sim ulator tests provide answ ers to crucial design ques­

tions related essentially to traffic safety.

B ut also driv ing sim ulators cannot give all final answ ers. D riv ing dynam ics sim ulation is

m ostly m issing in the sim ulators and in o ther cases it is poor. A lso the perceptual situation is

not realistic in the sim ulato r cabin. B ecause o f the darkened cockpits perceptual ergonom ics

aspects cannot be investigated.

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T hus the adjusted H M I design has to be im plem ented in a dem onstrato r car, allow ing for

testing o f the functions o f the in tegrated system under full d riv ing conditions, ga in ing the

requ ired insight fo r the last H M I design adjustm ents.

R E SU L T S A N D E X P E R IE N C E S

T he in tegrated sim ultaneous engineering and rapid pro to typ ing approach using p roduct sce­

narios as w ell as com puter dem onstration/sim ulation o f the H M I has p roven to be usefu l so

far fo r the developm ent o f the in-car H M I o f innovative em ergency handling system s fo r pas­

senger cars.

F igu re 2 : H M I d em onstrator, accessib le on the W W W

T he app lied scenario technique allow s fo r the functional specification and concep tualisation

o f the H M I, w hen im portan t technical decisions are still to be taken. C om puter sim ulation o f

the H M I w ith the rapid p ro to typing tool A L TIA provides dem onstrations and facilities for

user tests in an early phase o f the developm ent process. T he A L T IA dem onstra to r

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/s im u la to r has even been m ade accessible online v ia a W W W site and cou ld be used by p ro j­

ect partners fo r expert evaluations (figure 2). B oth, expert and user tests w ere p erfo rm ed in

o rder to analyse the deficits o f a lternative H M I design concepts.

The user tests and expert evaluations w ith the A L TIA sim ulation revealed w eak po in ts o f the

concep t and resu lted in an appropriate feedback for the op tim isation o f the concep ts and va lu ­

able input for fu ture design steps. T he critical issues m entioned at the ou tse t o f the pap er ca n ­

not be c larified w ith those com puter sim ulations. D riv ing sim ulato r tests are requ ired to

evaluate the design according to traffic safety aspects.

R E F E R E N C E S

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ters. In: P roceed ings o f the D R IV E C onference, B russels, F ebruary 4 -6 th , 1991

C arrera P ., Innocenti G. e t al: C ollision avoidance and A IC C : F unctional R equirem ents ,

T echnolog ical T rends, and E xperim ental R esults. In: P roceed ings o f the E A E C '95 , S tra s­

bourg , June 21-23rd , 1995

K aneda M ., U eno H . e t al: D evelopm ent o f a D row siness W arn ing System . In: P roceed ings o f

the 14th In ternational T echn ical E SV C onference, 1994

K atahara S.: D river D row siness D etection by E yelids M ovem ent from F ace Im aging . In P ro ­

ceed ings o f the 2nd ITS C ongress, N ovem ber 1995, 1995

N aab K., H oppstock R.: Sensor System s and S ignal P rocessing fo r A dvanced D river A ssis­

tance. In: Sm art V ehicles J.P . Pauw elussen & H .B . Pacejka (eds.), pp 69 - 97, 1995

W ierw ille W .W .: US IV H S R esearch: V ehicle B ased D row sy D river D etection . 6em e en tre-

tiens "V igilance e t transports” du centre J. C artier, D ecem ber 9 -10 th , B ron, 1993

W ierw ille W .W .: O verview o f R esearch on D river D row siness D efin ition and D river

D row siness D etection . In: P roceedings o f the 14th In ternational T echnica l E SV C onference ,

1994

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