Effects of Driver Characteristics on Seat Belt Fit Matthew P. Reed Jason J. Hallman Toyota Technical Center USA Sheila M. Ebert UMTRI
Crash Injury Data Older occupants are at greater risk in crashes Male, Belted, Driver, Passenger Car, Female, Belted, Driver, Passenger Car, 40% ! 40% ! Risk of AIS 3+ Injury (%) ! 51 kph Δ V, BMI=25 kg/m 2 ! Risk of AIS 3+ Injury (%) ! 51 kph Δ V, BMI=25 kg/m 2 ! Head ! Head ! 30% ! 30% ! Thorax ! Thorax ! Spine ! Spine ! 20% ! Abdomen ! 20% ! Abdomen ! UX ! UX ! LX ! LX ! 10% ! 10% ! 0% ! 0% ! 20 ! 30 ! 40 ! 50 ! 60 ! 70 ! 80 ! 20 ! 30 ! 40 ! 50 ! 60 ! 70 ! 80 ! Age (yr.) ! Age (yr.) ! Ridella et al. 2013 IRCOBI
Crash Injury Data Obese occupants are at greater risk in crashes Male, Belted, Driver, Passenger Car, Female, Belted, Driver, Passenger Car, 40% ! 40% ! 51 kph Δ V, Age=35 ! 51 kph Δ V, Age=35 ! Risk of AIS 3+ Injury (%) ! Risk of AIS 3+ Injury (%) ! 30% ! 30% ! UX (OR=1.16) ! UX (OR=1.16) ! LX (OR=1.83) ! LX (OR=1.83) ! 20% ! 20% ! 10% ! 10% ! 0% ! 0% ! 20 ! 25 ! 30 ! 35 ! 40 ! 45 ! 20 ! 25 ! 30 ! 35 ! 40 ! 45 ! BMI (kg/m2) ! BMI (kg/m2) ! Body Mass (kg) *Body Mass Index (BMI) = [Stature (m)] 2 Ridella et al. 2013 IRCOBI
Body Shape Data Human body shape varies widely Hybrid-III ATD Laser Scan Data
Research Question How is driver belt fit affected by age, gender, stature, and BMI?
Methods Men and women with a wide range of age and body size Measure Men (N=46) Women (N=51) Stature (mm) 1759 (85) 1601 (67) Body Weight (kg) 87.9 (17) 69.9 (16) Body Mass Index (kg/m 2 ) 28.4 (4.9) 27.3 (5.7) Erect Sitting Height (mm) 913 (40) 845 (42) Age (years) 58 (19) 59 (20) 2000 140 + + 1900 + + 120 + + + + + + + + + + + + + + + + + 1800 + + + + + + + Stature (mm) + + + + + + Weight (kg) 100 + + + + + + + + + + + + + + + + + + + + + + 1700 + + + + + + + + + + + + + + + 80 + + + + + + + + + + + 1600 + + + + + + + + + 60 + 1500 40 1400 1400 1500 1600 1700 1800 1900 2000 20 30 40 50 60 70 80 90 Stature (mm) Age (years)
Methods Driver mockup with 5 sets of belt anchorage locations Midsize Sedan Package L6 = 550 mm H30 = 270 mm 5 Belt Conditions: 3 lap belt angles with midrange D-ring 2 D-ring angles at midrange lap angle Lap Belt Angle: 30˚ 52˚ 75˚ FMVSS 210 Definition
Methods Landmarks measured with FARO Arm coordinate digitizer
Methods Additional body measurements in hardseat and laser scanner
Methods Belt fit measures Shoulder Belt: Lap Belt: Top of belt at Inboard edge of belt lateral position of at height of top of ASIS wrt ASIS sternum relative to midline
Methods Pelvis flesh margin estimates 300 250 Uncorrected Pelvis Depth (mm) 200 + + + + + + + + Corrected + + + + + + + + + + 150 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 100 15 20 25 30 35 40 45 50 B M I ( k g m 2 ) An adjustment was made to correct for the effects of adiposity on the distance between the surface landmark and the bone.
Results Lap Belt Fit X = -64 300 + B 250 + A 200 A Lap Belt Z (mm) 150 + + + + + + + + + + + 100 + + + + + + + + + + + + + + + + + + + + + + Z = 61 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 50 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 0 + + + + -250 -200 -150 -100 -50 0 50 B <=== Forward Lap Belt X (mm) Large symbols = obese Male + Female o
T060 T044 Results 80 years 24 years 35 BMI 29 BMI Lap Belt Fit 1663 mm 1621 mm -99, 117 -53, 83 X = -64 300 + B 250 T053 + A 72 years 200 Lap Belt Z (mm) 24 BMI 1697 mm 150 -64, 51 + + + + + + + + + + + 100 + + + + + + + + + + + + + + + + + + + + + + Z = 61 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + T029 + + + 50 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 28 years + + + + + + + + + + 20 BMI + 0 + + + + 1779 mm -250 -200 -150 -100 -50 0 50 -5, -1 <=== Forward Lap Belt X (mm) Large symbols = obese Male + Female o
Results Lap Belt Fit LapBelt X (mm) = 156 + 0.297 ELBA – 0.30 Age – 5.12 BMI – 0.04 Stature, R 2 adj = 0.57, RMSE = 25.8 Negative X is further forward Effective Lap Belt Angle (ELBA, deg): LBA taking into account driver-selected seat position LapBeltZ (mm) = -70.1 + 4.7 BMI, R 2 = 0.52, RMSE = 22.9 All effects and full model p<0.01
Results Lap Belt Fit + Age < 60 100 100 + Men O Age ≥ 60 O Women 50 50 + + + + 0 + + + LapBeltX (mm) + + + + + 0 + + + + LapBeltX (mm) + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + -50 + + + + + + + + + + + + -50 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + -100 + + + + + + + + + + + + + -100 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + -150 + + -150 + + + + -200 -200 20 25 30 35 40 20 25 30 35 40 B M I ( k g m 2 ) B M I ( k g m 2 ) belt further forward wrt pelvis BMI dominates effects of age and gender
Results Shoulder Belt Fit 200 25˚ 150 Shoulder Belt Score (mm) + + + + 100 + + + 21˚ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 50 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 17˚ + + 0 + 1500 1600 1700 1800 1900 2000 Stature (mm) Shoulder Belt Score (mm) = 338 – 22.3 YZAngle – 0.284 Stature + 0.0189 YZAngle*Stature, R 2 adj = 0.60, RMSE = 24.4 No significant effects of gender, BMI, or age
Results Comparison of Factor Effects Over relevant population ranges: Stature (1500-1850 mm), Age (20-80 years), BMI (20 to 40 kg/m 2 ), 300 Stature 100 BMI Stature 250 Age BMI Population Effect (mm) Age 50 200 Population Effect (mm) 150 0 100 -50 50 0 -100 LapBeltX LapBeltZ ShoulderBeltScore -50 LapBeltLength ShoulderBeltLength
Results Lap Belt Fit Mean belt locations with respect to ASIS at lateral location of ASIS (not occupant centerline) Midsize male pelvis in mean posture
Results Lap Belt Fit Mean belt locations with respect to ASIS at lateral location of ASIS (not occupant centerline) Midsize male pelvis in mean posture
Results Pelvis Locations and Abdomen Contours T184 30 years 23 BMI 1802 mm ATD Pelvis ATD Pelvis Flesh Laser scans obtained in slightly different posture Alignment based on measured human pelvis position and orientation
Results Pelvis Locations and Abdomen Contours T144 38 years 40 BMI 1865 mm ATD Pelvis ATD Pelvis Flesh Laser scans obtained in slightly different posture Alignment based on measured human pelvis position and orientation
Results Pelvis Locations and Abdomen Contours T147 87 years 27 BMI 1566 mm ATD Pelvis ATD Pelvis Flesh Laser scans obtained in slightly different posture Alignment based on measured human pelvis position and orientation
Results Pelvis Locations and Abdomen Contours T070 70 years 31 BMI 1630 mm ATD Pelvis ATD Pelvis Flesh Laser scans obtained in slightly different posture Alignment based on measured human pelvis position and orientation
Discussion Many people could place the lap belt in a lower location, closer to the pelvis Could they be educated to position the belt better? Narrow range of belt locations Wide range of belt locations
Conclusions Obesity has a strong effect on lap belt routing: On average, an obese individual places the belt fully above the pelvis and an average of 61 mm forward of the ASIS. Age has a smaller effect on belt routing than BMI across the population range Gender did not have a significant effect after accounting for stature Lap belt anchorage locations have much smaller effects than driver factors. The effects of BMI on lap belt fit were not significantly different for short/tall, men/women, old/young Shoulder belt fit is strongly affected by D-ring location and body size
Implications and Future Work Current ATDs with standard usage procedures are not capable of representing the large belt-skeleton offset and sub-optimal belt routing observed in this study, so current testing does not evaluate the load-sharing situations encountered by most occupants, particularly those who are obese.
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