MFT Human-vehicle-transport system interaction
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Transcript MFT Human-vehicle-transport system interaction
Simulator based assessment
of drivers with visual field
defects
Björn Peters, VTI
Sweden – some basic facts
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EU member state
EU driving license directive – specification
of minimum medical requirements
9.6 million inhabitants
6.1 million driving license group 1
1.6 million license holders +65 y
40 000 revoked licenses (all reasons)
(2013)
4 500 revoked licenses for medical
reasons annually (2013)
?? due to visual problem
100 applications for exemptions annually
Swedish requirements for peripheral visual
field Group I
Binocular Esterman screening test
2015-07-17
3
Swedish requirements for central visual field
Group I
Static threshold perimetry (Humphrey 24-2 or equivalent)
Within 10° from fixation:
Threshold in each
corresponding test
point should be 20 dB
or more
Within 20° from fixation:
Threshold in each
corresponding test
point should be 10 dB
or more (one missing
point is accepted)
2015-07-17
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≥10 dB
≥20 dB
The process in Sweden
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Mandatory for all physicians to report if medical requirement
not fulfil or agree with the patient to refrain from driving
(written consent)
Swedish Transport Agency (STA) decides if requirements
fulfilled –> OK, If not -> revoked license
Agree -> apply for exemption or Disagree -> appeal in court 3
levels
Apply for exemption -> added evidence of fitness to drive
required e.g.
• Simulator Based Assessment in Norway - SINTEF
• On-road assessment not sufficient
• Demand for a new Simulator Based Assessment Method
License with exemption – conditions can apply e.g. geographical
restrictions (2012 – 103, 2013 – 110)
Simulator test at SINTEF – reaction time
6 positions –
rural road 1
Press buttons to
respond
6 positions –
rural road 1
Results compared
to normative data
11 positions –
city road 1
Reaction times were recorded from 20 stimuli over a 15 minutes drive.
Stimuli size: 1. child head at 30 m, 2. adult body at 30 m,
Stimuli: duration 4 seconds
Developing a new assessment method at VTI
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Aim: determine if a driver with a visual field loss can
compensate and drive equally well as a driver without field loss
Approach: develop a relevant and realistic diving task with
more or less critical situations and build a matched reference
database (100+)
Simulator: high end simulator, dynamic, good visual system
Consider: simulator sickness and test conditions
Output: certificate stating driving performance/ability
compared to normative data
Assessment Validity: continuous follow-up and improvements
Simulator based assessment - pros and cons
Strengths
High level of control
Good internal validity
Same conditions for all
Critical situations with no risk
Realistic compared to clinical
testing
Reliable S-R testing
Eye tracking feasible
Weaknesses
Simulator driving - 3D in a 2D
world
Speed perception not ideal –
offset
Situations simplified compared to
real life
External validity partly good –
follow up needed
Simulator sickness
VTI Driving Simulator IV - Volvo XC 60 cabin
Rear- and SideMirror Displays
4 Video
Cameras
Virtual
Cockpit
Display
Sound
System
Rexroth hexapod
X-Y Sled 2,3 * 2,5 m
5 Gaze Tracking
Cameras
Shaker
Force Feedback
Steering Wheel
Sim IV visual projection system
9x Epson EB-410W projectors
Mersive SOL software
Auto calibration
Edge blending
Color correction
>180 degree field-of-view
Tillfälle att prova under dagen
Driving task and assesment criteria
• Approx. 50 km driving (rural, motorway, city)
• Critical situations (pedestrians, vehicles, bicycles, road works,
traffic light etc.)
• Assessment measures: speed, time, lateral position,
(collisions/incidents)
• Also: Time based safety margins (combination of TTC and THW)
• Reaction time to artificial stimuli (SINTEF like)
• Tentative assessment criteria exclude 2,5% of “low performers”
(previously used at SINTEF) - several measures
Tool for development, runs on a PC
SINTEF test - proposal
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Motive: compare data with SINTEF and other studies
Stimuli as SINTEF – traffic signs in 6 different positions
(false and true (STOP sign))
Simultaneous stimuli – right/left – controlling for over
compensation
Two buttons on the steering wheel
• One true stimuli (also combination with false) – press one button
• Two true stimuli – press two buttons
• One single or two false stimuli – press no buttons
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Separate part of the driving task
Clear written and oral instructions
Training before
Defining assessment criteria – a difficult task
Considering own and other road users’ safety
Not restrict if driving ability deemed sufficient
No solid scientific evidence for how much we need to see
in order to drive safely
Other examples
Alcohol (BAC - 0,2‰) fixed – should it be differentiated?
Deafness OK to drive – why?
Epilepsy – OK with medication and no seizure for 3 months
Dementia – when is the right time to stop?
Mobility impairments – what is sufficient adaptation?
Whatever we do we need to follow-up!
Visual and cognitive tests
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Visual acuity
Visual field of view test - Humphrey
Useful Field of View (UFOV)
Trail Making Test (TMT A&B)
Dynamic TMT (New)
Perceptual speed (Operative)
Attentional demanding (Operative/Tactical)
Working memory (Tactical/strategic)
Meta memory (Strategic)
Useful field of view (UFOV)
Dynamic Trail Making Test
Persons with visual field defects interested to
participate
Until 15 April 222 interested
189 replied a short survey
Data for recruiting 100 reference drivers
Most have sent their visual field data
Select a small, relevant group of drivers to
participate in the project
• Delivery date mid - 2014
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Age, gender, experience for selection of
reference drivers
Age
18-24
25-34
35-44
45-54
55-64
65-74
75Total
Male Female Total
4
1
5
1
1
2
12
9
21
22
5
27
36
8
44
63
2
65
25
0
25
163
26
189
Most male,
< 70% 55 +
Age
18-24
25-34
35-44
45-54
55-64
65-74
75Totalt
Num
5
2
21
27
44
65
25
189
Median distance
km/week
40,0
202,5
250,0
300,0
200,0
200,0
150,0
200,0
Min 10000 km/y
Max 25000 km/y
Diagnoses
Diagnosis,
free
Stroke
Glaucoma
Diabetes
Eye injury
Brain tumor
Other
Total
Missing
Totalt
Num
69
60
21
17
7
4
178
11
189
%
36,5
31,7
11,1
9,0
3,7
2,1
94,2
5,8
100,0
% of those
with a
diagnosis
38,8
33,7
11,8
9,6
3,9
2,2
100,0
Cumulative % of
those with a
diagnosis
38,8
72,5
84,3
93,8
97,8
100,0
Select based on diagnosis and visual
field defect
Difficult driving situations
Questions,
comments?