tTNO Human Factors
Driving behaviour effects of the Chauffeur Assistant
Jeroen Hogema
16 December 2003 2t
Overview
• Background• Method
• TNO driving simulator• Simulating the CA• Experimental design
• Results• Conclusions
• consequences for traffic simulation model
16 December 2003 3t
Dutch Evaluation of the Chauffeur Assistant (DECA)
• Chauffeur Assistant • Adaptive Cruise Control• Lane Keeping System
• Follow-up of Lane Departure Warning Assistant FOT
• Transport Research Centre (TRC) • Ministry of Transport, Public Works, and Water Management
16 December 2003 4t
Chauffeur Assistant: Questions
Individual driver level• driving behaviour• workload• acceptance
traffic flow level• traffic performance• safety indicators
16 December 2003 5t
DECA
DRIVING SIMULATO
R behaviour
TNO
MIXIC
interpretationreport
MIXIC simulation
s
TRC
workload
acceptance
driver
CA
CA
16 December 2003 6t
Method – Driving simulator
• visual• audio• steering
force• motion
16 December 2003 7t
Method – Driving simulator• DAF 95XF lorry• Mass 20500 kg (fully loaded)• Maximum engine power: 350
kW
• Parameter set from DAF trucks
16 December 2003 8t
Method – Simulating the CA
• Adaptive Cruise Control
DC specifications• Distance law for car-following
• Dref = 6.0 + 1.3 * v• Dref = ACC's intended following distance (m)• v=current speed (m/s)•
• Braking: max. -3 m/s2
16 December 2003 9t
Method – Simulating the CA• ACC controller
• structure from earlier work
• parameters from recent ACC work by TNO Automotive
16 December 2003 10t
Method – Simulating the CA
ACC reference scenarios• approaching• braking lead car• accelerating lead car• cut-in
Dynamic behaviour of• reference model• driving simulator CA• MIXIC CA
0 10 20 30 40 50 6020
21
22
23
spee
d (m
/s)
Scenario 3
DS ref
0 10 20 30 40 50 6010
20
30
40
dist
(m
) DS ref
0 10 20 30 40 50 60-2
-1
0
1ac
c
time (s)
DS ref
16 December 2003 11t
Method – Simulating the CA
LKS• noise added to obtain realistic servo
performance• SDLP about 10 cm
0 50 100 150 200 250 300-0.2
0
0.2
y (m
)
Scenario 101
0 50 100 150 200 250 300-0.5
0
0.5
fi(de
gr)
0 50 100 150 200 250 300-1
0
1
2
dels
(deg
r)
time (s)
lateral position,heading angle
wheel angle state
vehicle
gear ratio
delta_ref
control loader
Noise
. steer.whl.angle
LKS
16 December 2003 12t
Method - Experimental design (1)• with vs without CA• traffic volume
• low (3400/u) • high (6000/u)
• 3-lane motorway, 3.5 m wide lanes
ACC headway• Dref = 6.0 + tk * v
• tk = 1.0 – 1.3 – 1.6 s
• 1 preferred setting selected by each driver prior to experiment
16 December 2003 13t
Method - Experimental design (2)
Scenarios• car-following (overtaking possible)• braking lead car
• 3 m/s2
• 4 m/s2
Subjects• 18, professional truck drivers• at least 5 years 'groot rijbewijs'• age between 25-55• paid for their participation
16 December 2003 14t
Human Machine Interface
• driver turns CA turns on/off • switches• brake pedal
• driver sets ACC speed• buzzer at maximum
braking
display• ACC set speed on
speedometer• symbol: headway
control or speed control
16 December 2003 15t
Results – preferred CA time headway
1.0 s 1 x1.3 s 8 x1.6 s 9 xTotal 18 x
16 December 2003 16t
Results – SD lateral position
• effect of CA
low vo lume high vo lume
without with
C A
0.0
0.1
0.2
0.3
0.4
0.5
SD
LP
(m)
16 December 2003 17t
Results – Time to Line Crossing
• effect of CA
low vo lume high vo lume
without with
C A
2.0
2.5
3.0
3.5
4.0
TL
Cm
in (s)
16 December 2003 18t
Results – close following
• effect of CA
low vo lume high vo lume
without with
C A
0
1
2
3
4
5
% T
HW
< 1
s
16 December 2003 19t
Results – lane change frequency
• effect of CA on edge of marginal significance [p<.11]
low vo lume high vo lume
without with
C A
5
6
7
8
9
lan
e ch
an
ge
s (/15
min
)
16 December 2003 20t
Braking lead car: lane change response
CA Changes lanewithout 37 out of 103 36%with 17 out of 107 16%
lane change reaction of subject
Fewer lane changes with CA
decel. Changes lane3 m/s^2 26 out of 127 20%4 m/s^2 24 out of 67 36%
16 December 2003 21t
Braking lead car: braking response
leader decel. subject max. dec.3 m/s^2 3.5 m/s^24 m/s^2 4.3 m/s^2
braking reaction of subject
lower deceleration levels with CA
CA subject max. dec.without 4.3 m/s^2with 3.5 m/s^2
16 December 2003 22t
Results – mental effort
• Rating Scale of Mental Effort• effect of CA
without with
C A
30
40
50
60
70
RS
ME
somewhat
ra ther
high vo lume low vo lume
16 December 2003 23t
Acceptance (1)
Mean Std.Dev.
useful-useless 1.2 0.7
pleasant-unpleasant 1.3 0.9
good-bad 1.1 0.8
nice-annoying 0.9 1.1
effective-superfluous 1.1 0.9
likeable-irritating 1.3 0.7
assisting-worthless 1.4 0.8
desirable-undesirable 1.2 0.9
raising alertness-sleep inducing-0.2 1.1
• -2..2 scales:
16 December 2003 24t
Acceptance (2)
Underlying variables
• USEFULNESS: + 0.93• SATISFACTION: + 1.10
16 December 2003 25t
Summary of results (1)
With Chauffeur Assistant…
• reduced SD of lateral position
• higher Time to Line Crossings
• less short time headways
• reduced Mental Effort• (fewer changes with
CA?)
16 December 2003 26t
Summary of results (2)• Acceptance: positive
• except “sleep-inducing”
Lane changes• fewer changes with CA?
Braking lead car• fewer lane changes with
CA• less critical behaviour
with CA (maximum deceleration, minimum TTC)
No effects on:• mean, s.d. speed• lane use (% right
lane)• mean lateral position• mean time headway
16 December 2003 27t
Chauffeur Assistant in MIXIC
driver vehicle
CA
16 December 2003 28t
Chauffeur Assistant in MIXIC
DRIVER
VEHICLE
CA
car following
free driving
lane change model
LATERAL
LONGITUDINAL
settingstransitions
CA
16 December 2003 29t
MIXIC driver model
Driver – CA• CA settings
• CA reference speed = driver’s intended speed• CA reference headway: 50% 1.3 s; 50% 1.6 s
• CA off when:• CA is braking hard AND driver would brake harder• starting lane-change manoeuvre
• CA on when:• “possible”
16 December 2003 30t
MIXIC driver model
Lane change behaviour• small effects• nature of effects unknown
• tactical level: avoid getting 'stuck' in car-following in a 'slow' lane
• driver-state related: reduced alertness, complacency, less 'active' driving
• => no changes in lane change model
16 December 2003 31t
Conclusions
• Behaviour• Workload effects in line with ACC or LKS
research• Acceptance
}Chauffeur Assistant – ACC + LKS:
contribution of ACC and LKS unknown
Minor modifications to MIXIC->driver->ACC model
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