Slide 1
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Optimizing Seat Design To Reduce Risk
Of All-Terrain Vehicle Crashes
Charles Jennissen, MDGerene Denning, PhDNathan MillerKaiyang TangDepartment of Emergency MedicineUniversity of Iowa Carver College of Medicine
Daniel McGehee, PhDThomas Schnell, PhDJonathon Marsico, BSJohn Steffen, MSUniversity of Iowa College of Engineering
Slide 2
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
All-Terrain Vehicles (ATVs)
Sports ATVUtility ATV
Slide 3
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Single-Person DesignMost ATVs are designed and recommended
for use by only one person at a time.
Slide 4
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Long ATV SeatsHowever, many ATVs have long seats that appear large
enough to accommodate passengers.
The presence of extra riders increases the likelihood of a crash, especially rollovers and ejections.
31% of victims in fatal crashes are operators with passengers or passengers themselves.
Slide 5
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Objectives of Study
To define the characteristics of ATV seat size and placement for existing makes and models.
To determine whether there was a design that would allow for proper “active riding” while reducing the likelihood of:
• Multiple riders.
•Age-inappropriate operation
Slide 6
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
MethodsAnalyzed ATV seat dimension
requirements in a 26 degree incline/decline study
Developed and validated a Photoshop™-based measurement method.
Performed measurements for a convenience sampling of ATV models at several dealerships.
Slide 7
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
INCLINE/DECLINE STUDYRESULTS
2006 John Deere Trail Buck 650 cc ATV.
6.0 ft. (183 cm) male
Slide 8
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Incline/Decline Study
When going downhill, a rider must:
• Fully extend arms
• Move bottom back on the seat
Result= Moving body back on seat keeps center of gravity behind the front tires to avoid a front rollover.
Slide 9
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
When going uphill, a rider must:
• Lean forward while bending their arms.
• No shifting forward on the seat is normally required.
Incline/Decline Study
Result = Leaning forward sufficiently shifts center of gravity ahead of the rear tires to prevent a backward rollover.
Slide 10
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Steeper Inclines
With significant uphill inclines, many experts suggest standing and leaning forward to position your weight towards the front wheels.
Slide 11
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Passengers
Passengers prevent these weight shifting requirements
A passenger in front of the rider, like a child, will not allow the rider to lean forward when going uphill.
A passenger behind the rider will prevent the rider to move back on the seat when heading downhill.
Both scenarios increase the probability of a roll-over.
rock
yroo
stm
x.co
m
Slide 12
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Preliminary Conclusions/Hypotheses
Active riding requires shifting the operator’s center of gravity on inclines/declines.
The rear edge of the seat should be near the rear axle (prevent forward rollover).
The seat does not need to extend forward toward the handle grips beyond what will comfortably accommodate an adult rider (prevent backward rollover).
Slide 13
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
ATV MEASUREMENTS AT DEALERSHIPS-
PILOT STUDY RESULTS
Slide 14
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Make Model YearEngine Size
(cc)Handle Stem to Front
of Seat (in.)Seat
Length (in.)Handle Stem to Back
of Seat (in.)
Utility
Bombardier John Deere Buck 2006 650 14 29 43
Polaris Trail Boss 2010 330 9 35 44
Polaris Sportsman 2010 500 11 29.5 40.5
Polaris Sportsman 2010 800 11 29.5 40.5
Polaris Sportsman 2010 850 10 31 41
Yamaha Grizzly 2010 350 17 23 40
Yamaha Grizzly 2010 450 17 22 39
Yamaha Grizzly 2010 700 19 22 41
Honda Rancher 2010 420 14 24 38
Honda Rubicon 2010 499 17 26 43
Honda Ricon 2010 675 16 27 43
Kawasaki BruteForce 2010 750 14 31 45
Sport
Yamaha Raptor 2010 700 12 31 43
Yamaha YFZ450R 2010 450 10 32 43
ResultsThe seats of fourteen adult-sized utility and sport ATV
models from five major distributors were measured.
Slide 15
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Pilot Results
Seat lengths varied from 22-35 inches in length.
The back of the seats ended fairly consistently at 38-45 inches away from the handlebar attachment.
Most of the difference in seat lengths was accountable by the distance from the handlebar attachment to the front of the seat which varied from 9-19 inches.
Slide 16
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
ATV MEASUREMENTS WITH A ADOBE PHOTOSHOP™-BASED
METHODOLOGY
Slide 17
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Methods
Developed a novel Adobe Photoshop-based methodology to measure lengths and distances.
Performed measurements on 77 new ATV models from 8 manufacturers using downloaded images.
X X
6
Slide 18
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Methodology Validation
This methodology was validated by: Comparison with direct
measurements at dealerships (N=12, Pearson correlation coefficient 0.95 )
Comparison of results from two independent measurers (N=20, Pearson correlation coefficient 0.96).
The average error ± SD in calculated vehicle length was 1.8% ±1.2%.
Enter wheelbase dimension in “Length”
box.
Slide 19
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat lengths on adult ATVs are highly variable.
Polaris has the longest seats.
Arctic Cat has the shortest seats.
Slide 20
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Sports ATVs have longer seats than utility ATVs.
Utility ATV
Sports ATV
N=21 N=46
Slide 21
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
PolarisTrail Boss
Sports ATVs have longer seats than utility ATVs.
Slide 22
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat Length and Engine Size (No Correlation)
Slide 23
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat Length by Wheelbase and ATV Style
Weak Positive Correlation
Slide 24
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat Length by Wheelbase and ATV Maker
Make Pearson r Correlation
Polaris -0.54 moderate negative correlation
Arctic Cat -0.37 moderate negative correlation
Can Am -0.31 weak negative correlation
Honda -0.08 no correlation
Yamaha +0.17 weak positive correlation
Kymco +0.44 moderate positive correlation
Suzuki +0.74 strong positive correlation
Kawasaki +0.87 strong positive correlation
Weak is >0 to <0.3Moderate is 0.3 to <0.7Strong is 0.7 and higher
Correlations varied greatly.
Slide 25
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat Placement-Arctic Cat
Slide 26
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Seat Placement-Polaris
Slide 27
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Summary of Results
Seat lengths for adult-sized vehicles ranged from 20-37 inches.
75% of all seat backs ended near or over the rear axle.
Shorter distances from the handle grips to the front of the seat generally resulted in longer seats.
This distance ranged from 3.3-19 inches.
Slide 28
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Overall ResultsOur results demonstrate that there are no industry-wide
standards for seat length and placement.
No apparent consistency in ATV seat design safety consideration.
elec
tric
mot
o.co
m
Slide 29
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Conclusions/Hypotheses
Passengers and use by under-age operators are major risk factors for ATV-related deaths and injuries.
Slide 30
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Conclusions/HypothesesStandardized criteria for seat length and
model-appropriate seat placement should be implemented.
• Starting seats further from handle grips.
• Ending seats not further than the rear axle.
Such steps could improve safety by:
• Reducing likelihood of passengers.
• Reducing likelihood of age-inappropriate operation.
Regulations may be needed to ensure seat design changes are incorporated throughout the industry.
Slide 31
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Questions?
Slide 32
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Photoshop™ Methodology
X X
6
VanishingPoint First steps:
•Download quality image•Mark near hubs•Identify vanishing point•Connect vanishing point and near hubs
Next steps:• Identify and mark far hubs (circle method)•Find center of axles
Midpoints
Slide 33
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Final steps:
• Create plane through center of axles.
• Set scale by entering manufacturer wheelbase dimension.
Enter wheelbase
dimension in “Length” box.
• Draw vertical lines in plane.
• Measure between vertical lines.
• Total = 77 models
• Measurer 1 vs. Measurer 2 (20 models)
• Photoshop vs. In-field(12 models)
Photoshop™ Methodology
Slide 34
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Error[Absolute (Measured vehicle length-Manufacturer vehicle
length)]/Manufacturer vehicle length] expressed as %.
97 measurements (77 Measurer 1 + 20 Measurer 2)
The average error ± SD in calculated vehicle length was 1.8% ±1.2%.
Slide 35
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Measurer 1 vs. Measurer 2
20 24 28 32 36 4020
24
28
32
36
40 Pearson r = 0.95 = Strong positivep<0.0001
Seat Length (Measurer 1)
Slide 36
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
N = 12 models also done by the Photoshop™ Method
Build measuring device.
Measurements at Dealerships
Lengths and distances
• Left end of device placed at leftmost point.
•Keeping level, right end of device placed at rightmost point.
•Clamps tightened and ruler used to provide measurement.
Slide 37
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
Photoshop™ vs. In-field
20 24 28 32 36 4020
24
28
32
36
40 Pearson r = 0.95 = Strong positivep<0.0001
Seat Length (Photoshop)
Slide 38
University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine
However, both have seats long enough to accommodate a passenger.
Adult Youth
N 67 10
Mean (SD) 27.8 (3.9) 24.5 (2.5)
95% CI 26.8, 28.7 22.7, 26.2
Median 28.1 24.2
MinMax
19.837.0
21.129.2
t test P = 0.013
Adult ATVs have longer seats than youth ATVs.