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BioRID II manikin and human seating position in relation to car headrestraintBertil Jonssona; Mats Y. Svenssonb; Astrid Linderc; Ulf Björnstiga

a Department of Surgical and Perioperative Sciences, Division of Surgery, Umeå University, Umeå,Sweden b Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden c

VTI, Swedish National Road and Transport Research Institute, Göteborg, Sweden

To cite this Article Jonsson, Bertil , Svensson, Mats Y. , Linder, Astrid and Björnstig, Ulf(2008) 'BioRID II manikin andhuman seating position in relation to car head restraint', International Journal of Crashworthiness, 13: 5, 479 — 485To link to this Article: DOI: 10.1080/13588260802120926URL: http://dx.doi.org/10.1080/13588260802120926

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International Journal of CrashworthinessVol. 13, No. 5, October 2008, 479–485

BioRID II manikin and human seating position in relation to car head restraint

Bertil Jonssona∗, Mats Y. Svenssonb, Astrid Linderc, and Ulf Bjornstiga

aDepartment of Surgical and Perioperative Sciences, Division of Surgery, Umea University, Umea, Sweden; bDepartment of AppliedMechanics, Chalmers University of Technology, Goteborg, Sweden; cVTI, Swedish National Road and Transport Research Institute,

Goteborg, Sweden

(Received 18 December 2007; final version received 8 April 2008)

The objective of the study was to compare stature, weight and backset (the horizontal distance (x) between the back of theoccupant’s head and the front of the seam on top of the head restraint) of the Biofidelic Rear Impact Dummy (BioRID II) tothe same variables on seated volunteers in a car. The following methods were used. Data were collected from 154 randomlyselected Swedish individuals (78 males and 76 females). The volunteers and the BioRID II were examined in a Volvo V70car, year model 2003, in three positions: driver (hands on steering wheel), front passenger (hands in lap) and rear passenger.The study results were as follows: the BioRID II was found to correspond approximately to a 35th–45th percentile male instature (−2 cm), a 35th percentile male in weight (−7 kg), a 96th percentile female in stature (+11 cm) and a 69th percentilefemale in weight (+8 kg). The BioRID II was designed to represent a male driver. The BioRID II backset correspondedwell with the average of the male drivers of its stature. Larger deviations in backset were found for other volunteer sizesand other seating positions. The average backsets were 26 mm for females and 63 mm for males in the front seat positions.The volunteers had larger backset in the driver position (60 mm) than in the front passenger position (29 mm). Smallerdifferences in backset were seen between the BioRID II and the volunteers in the rear passenger position. This study providesdata regarding the occupant size coverage of BioRID II, and unique data regarding backset, of different occupant positions inthe car; driver with hands on steering wheel, and front and rear passengers with hands in lap, for female and male in relationto the BioRID II dummy.

Keywords: BioRID II; stature; weight; backset; gender; position

Introduction

Although the pathological cause of whiplash injury is stillunknown, there is a large body of knowledge regardinginjury-generating factors. Factors causing increased risk in-clude female gender, large backset and driving position. Asknowledge about injury criteria increases, the need arisesfor tools that can be used by car manufacturers to evaluatetheir designs. Many evaluations can be made using com-puter simulations, but there will always be a need for realtest crashes and occupant substitutes, like the BioRID IIdummy. In order to evaluate seat designs in a standardisedway, several test protocols have been developed by, for ex-ample, the International Organization for Standardization(ISO) [7], the Research Council for Automobile Repairs(RCAR) [13] and the Research Council for Automobile Re-pairs – International Insurance Whiplash Prevention GroupRCAR-IIWPG [14]. These protocols include a procedurefor positioning the BioRID II in a seat when performing adynamic test of a rear impact.

The size and shape of the BioRID II dummy werederived by Schneider [16] using anthropometric datafrom the University of Michigan Transportation ResearchInstitute (UMTRI). The choice to use the size of an existing50th percentile male dummy was made in order to simplify

∗Corresponding author. Email: bertil.jonsson@ornsat.com

the development, as it allowed the use of some existingdummy parts, such as extremities and head [3,4]. Anotherreason for this choice of size was that it could representnot only a normal-sized male, but also because this sizewas quite representative of a tall female, being one of thehigh-risk occupants [10].

New data from a Swedish population were recently pre-sented by Jonsson et al. [9], who studied female and maleseat adjustment precision and repeatability. There was asignificant difference between the settings for males andfemales, mainly due to stature differences.

The aim of this study was to analyse how well theBioRID II, when positioned according to the ISO [7],RCAR [13] and RCAR-IIWPG [14] protocols, correspondsin size and backset to data from a randomly selected pop-ulation of Swedish female and male volunteers, sitting asdrivers (hands on the steering wheel) and as front and rearseat passengers (hands in the lap).

Method

Human volunteers

Test volunteers were age and gender stratified, but oth-erwise randomly recruited from among (i) visitors to the

ISSN: 1358-8265Copyright C© 2008 Taylor & FrancisDOI: 10.1080/13588260802120926http://www.informaworld.com

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480 B. Jonsson et al.

Swedish Vehicle Inspection Company (Svensk BilprovningAB) in Ornskoldsvik, and (ii) citizens in the community ofOrnskoldsvik. The Swedish Vehicle Inspection is a bodywhich conducts annual vehicle inspections on the Swedishcar fleet of 4.2 million cars; 3.4 million of these cars haveprivate owners SIKA [17]. The inclusion criteria were avalid class *B**** driving license, and pain-free neck, tho-racic and shoulder regions. In total, 154 volunteers (78 menand 76 women) participated in the study and were the sameindividuals as in study [8,9]. Data regarding stature, weight,seat adjustment and backset were collected at the same oc-casion. The mean age of the men was 46 years (standarddeviation SD = 11), and the mean age of the women was48 years (SD = 11). The volunteers were given written andoral information about the study’s aim and procedure beforethey gave their consent to participation.

Measuring equipment

The test car was a Volvo V70 model, year 2003, manufac-tured for the US market; both front seats were equippedwith an electric power seat, model P2. The volunteers wereinstructed to adjust the front seat in their preferred way,using the same routine as in an earlier study by Jonssonet al. [8]. Self-selected posture backset was measured withthe same equipment and method as described below forthe BioRID II.

The manikin used in this study was a BioRID II, ver-sion H. A measurement device was constructed to measurehead position in the sagittal plane, as compared to a 0-reference point at the head restraint; the same device wasused for both manikin and volunteers. The device was con-structed from two movable metal rods with a lockable nutat the grade scale in between; see Figures 1 and 2. A sec-ond and lower grade scale was mounted on a metal framewhich was inserted into the normal position for the headrestraint attachments. The position of the movement centreof the lower grade scale was carefully measured in relationto the upper and frontal fabric rim of the head restraint0-reference point (A); see Figure 3. The X- and Y -valueswere calculated on a laptop on the basis of the known lengthof the rods, seat back angle (γ ) and the values of the twograde scales (α, β) with the following formulae:

Horizontal distance (X) in mm = (300 · cos(180 −α) + 400 · cos(α + β − 180)) · cos(γ ) + (300 · sin(180 −α) − 400 · sin(α + β − 180)) · sin(γ ) − 248.

Vertical distance (Y ) in mm = (300 · sin(180 − α) −400 · sin(α + β − 180)) · cos(γ ) − (300 · cos(180 − α) +400 · cos(α + β − 180)) · sin(γ ) − 252where α is the angle lower grade scale, β is the angle uppergrade scale and γ is the angle seat back.

The maximum intrapersonal measuring inaccuracy inreading the grade scales was ±0.5◦, leading to a possiblemeasuring error of ±2 mm in the horizontal direction (X-values) and ±1 mm in the vertical direction (Y -values).

Measuring points on the BioRID II and seat/headrestraint

The measuring point on the BioRID II was the most rear-ward point of the dummy head, corresponding to the ex-ternal occipital protuberance on the back of the head onvolunteers; see Figure 1. The 0-reference point (A) on theseat was set to the frontal aspect of the seam of the fabricon top of the head restraint; see Figure 3. After BioRIDII setup according to the protocols [7,13,14], the head re-straints in the front and rear seats were removed, in orderto allow comparative evaluation of volunteer seating pref-erences without sagittal guidance from the head restraint.

Test positions and procedure – BioRID IImeasurements

The BioRID II was measured in (i) driver position and(ii) front passenger position according to the proceduredescribed in the ISO [7], RCAR [13] and RCAR-IIWPG[14] protocols, with the exception of the driver position,where the hands were placed on the steering wheel as shownin Figure 1. The front seat measurements were performed ina mock-up of the front seat and steering wheel, as shown inFigure 1. The rear seat measurement was performed usingthe internal test procedures and settings of Volvo Cars, asdescribed in Table 1; see Figure 2. BioRID II positioningwas performed by specialists from Volvo Cars.

Before positioning the BioRID II in the front seat ac-cording to the ISO, RCAR and RCAR/IIWPG protocols,the SAE J826 manikin was used to set H-point and torsoangles. After BioRID II protocol setup, the head restraintsin the front and rear seats were removed. The calculationsused to determine backset made use of the horizontal dis-tance (X) between the 0-reference point (Figure 3) and theback of the volunteer’s or the BioRID II head. The hor-izontal distance difference between the two measurementtechniques (ISO, RCAR, RCAR-IIWPG protocols (B) andthe 0-reference point (A) in Figure 3 used in this study) was40 mm in the front seats and 25 mm in the rear seat, due tothe design of the head restraint; this resulted in a BioRIDII backset of 75 mm (40+35 mm) in the front seat and 100mm (25+75 mm) in the rear seat; see Tables 2, 3 and Figure3. This is important for further reading and understandingof the study data.

Results

BioRID II and human data: stature,weight and backset

Backset: female

For females, the mean backset was 39 mm in the driver po-sition, 13 mm in the front passenger position and 98 mm inthe rear passenger position. The BioRID II backset values(73 mm in the driver position, 76 mm in the front pas-senger position and 94 mm in the rear passenger position)

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International Journal of Crashworthiness 481

Figure 1. BioRID II, equipped with the measuring device, in the driver position.

corresponded to an 82nd percentile female in the driverposition, a 95th percentile female in the front passengerposition and a 41st percentile female in the rear passengerposition; see Table 2.

Backset: male

For males, the mean backset was 81 mm in the driver posi-tion, 44 mm in the front passenger position and 109 mm inthe rear passenger position. The BioRID II backset values(73 mm in the driver position, 76 mm in the front passenger

position and 94 mm in the rear passenger position) corre-sponded to a 39th percentile male in the driver position,a 79th percentile male in the front passenger position anda 37th percentile male in the rear passenger position; seeTable 3.

Discussion

The measurements performed in this study made use of acar which had achieved a good geometrical rating for itshead restraint design in IIHS [6] testing. The interaction

Figure 2. BioRID II, equipped with the measuring device, in the rear passenger position.

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482 B. Jonsson et al.

Figure 3. The H-point SAE J826 manikin with a head restraint measuring device. A denotes the 0-reference point for measuring backseton BioRID II and volunteers. B is the horizontal distance between an imaginary vertical line passing through the 0-reference point, andthe most frontal aspect of the central part of the head restraint. The value of B was 40 mm in the front seat and 25 mm in the rear seat. Xdenotes the horizontal measuring direction, and Y the vertical measuring direction.

between human sizing data, seat/head restraint design andBioRID II geometrical design can be studied and evaluated,and if found to be of good quality, can serve as a model forother manufactures of seating systems.

The BioRID was made by a Swedish consortium tomimic the kinematics and kinetics of a human in rear endimpact; at the time of its design and manufacture, no otherdummy of this kind was available. The dummy design wasbased on available UMTRI anthropometry data, includinginformation about stature, weight and sitting posture in-cluding back curvature. The anthropometry data used inthe present study provide information on current occupant

sizes of a Swedish population. These new data allow evalu-ation of how backset settings in volunteer seating positionsdiffer from the standardised sitting positioning procedureof the BioRID II, and also contribute to showing how rep-resentative the BioRID II is in size.

Stature and weight

The anthropometry data in this study are quite represen-tative for the Swedish population, especially as regardsstature. The mean stature and weight of the volunteers were179.6 cm and 86.9 kg for the males, and 166.8 cm and

Table 1. Positioning details for the H-point manikin SAE J826 and the BioRID II.

Front seat Rear seatH-point H-pointmanikin manikin

Settings SAE J826 BioRID II SAE J826 BioRID II

Horizontal distance between back of head and head restraint (mm) 20 35 60 75Torso angle (degrees) 25 25 30 30Height (mm) 24 NA 85 NAPelvic angle (degrees) NA 26.5 NA 31.5Seat motor settingsMotor 1: Length adjustment (revolution from rearward 0-starting point = mid range) 755 755 Fixed FixedMotor 2: Seat back angle adjuster (revolution from rearward 0-starting point) 1613 1613 Fixed FixedMotor 3: Rear seat pan height adjustment (revolution from

from rearward 0-starting point = mid range) 252 252 Fixed FixedMotor 4: Front seat pan height adjustment (revolution

from rearward 0-starting point = mid range) 192 192 Fixed Fixed

NA = not available.

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International Journal of Crashworthiness 483

71.1 kg for the females. In comparison, stature and weightfor the whole Swedish population (16–84 years) are 179.5cm and 82.4 kg for males, and 165.5 cm and 66.6 kg forfemales SCB [15]. Local survey data from VasternorrlandCounty Council [18] show that males are 1.2 kg heavierand 1.3 cm shorter, and females are 2.4 kg heavier and 0.5cm shorter in the local community than shown by nationalSCB data [15]. This explains some of the weight difference(+4.5 kg) between local and national Swedish data. UMTRIdata by Schneider [16] from the HANES survey, conductedbetween 1971 and 1974 in the United States for the 18–74 age group, showed stature and weight of 175.3 cm and77.1 kg for males, and 161.5 cm and 62.1 kg for females.Thus, for both genders, the stature and weight differencesbetween the United States and Sweden over slightly morethan 30 years are about 4 cm and 5 kg, respectively.

As shown in Tables 2 and 3, the 50th percentile maleBioRID II corresponds to a 35th–45th percentile male instature and a 35th percentile male in weight, and to a 96thpercentile female in stature and a 69th percentile femalein weight. The BioRID II is 11 cm taller and 8 kg heavierthan a 50th percentile female. Swedish females are tallerthan those in the United States, with a stature of 165.5 cm,compared to 162.5 cm for US females [11]. Mean female

stature varies in other countries; the mean stature of femalesin 10 European countries is 163.7 cm [2], that of Chinesefemales is 154.5 cm Bell [1] and that of Brazilian femalesis 160.3 cm [5]. Dutch and Norwegian females are slightlytaller than Swedish females [2]. The sitting male and fe-male data determined by the present study could provide avaluable input to the design of a possible next member ofthe BioRID family, which thus could be made to representa larger part of the female population.

Backset

The most obvious finding in this study was the difference inbackset between a driver with hands on the steering wheeland a front seat passenger with hands resting in lap. In bothgenders, the mean backset for males in the front passen-ger position was roughly half that for the driver position,and the corresponding data for females was 1/3. Backset in-creased for both males (37 mm) and females (26 mm) whenvolunteers held their hands on the steering wheel (driver po-sition), in comparison to the front seat passenger posture; noother postural changes were made. In volunteers, this pos-ture change was mainly produced by increased kyphosis inthe thoracic spine.

Table 2. Female volunteer data for stature (cm), weight (kg) and backset (mm), and corresponding Bio-RID II data. Female data arepresented in 5-percentile steps. Backset is defined as the horizontal distance between the back of the head and the front of the seam on topof the head restraint.

Driver Front seat passenger Rear seat passengerBioRID II Stature (cm) Weight (kg) Backset (mm) Backset (mm) Backset (mm)

178 78 73 76 94Females n = 76 Stature (cm) Weight (kg) Backset (mm) Backset (mm) Backset (mm)Median 167 70 41 10 100Mean 167 71 39 13 98SD 7 13 36 31 26Range 152 48 −29 to 117 −46 to 95 36 to 197Female Percentile5 156 51 −18 −36 5810 158 54 −7 −23 6415 160 58 −1 −19 6820 160 60 3 −15 7225 163 62 9 −9 8030 163 63 13 −7 8235 163 65 20 −4 8840 165 65 32 5 9345 167 68 37 7 9650 167 70 41 10 10055 168 71 43 14 10160 168 74 50 17 10465 170 75 56 21 10970 170 79 61 27 11175 171 80 64 32 11280 172 82 69 41 11585 174 85 79 46 11890 175 90 89 58 13695 177 95 102 73 150

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484 B. Jonsson et al.

Table 3. Male volunteer data for stature (cm), weight (kg) and backset (mm), and corresponding Bio-RID II data. Male data are presentedin 5-percentile steps. Backset is defined as the horizontal distance between the back of the head and the front of the seam on top of thehead restraint.

Driver Front seat passenger Rear seat passengerBioRID II Stature (cm) Weight (kg) Backset (mm) Backset (mm) Backset (mm)

178 78 73 76 94Males n = 78 Stature (cm) Weight (kg) Backset (mm) Backset (mm) Backset (mm)Median 180 85 82 45 107Mean 180 87 81 44 109SD 6 16 44 35 31Range 167 63 −5 to 209 −27 to 152 50 to 224Male percentile5 168 67 9 −12 6210 172 68 17 −7 7115 173 71 38 3 7720 173 73 45 14 8125 175 74 47 20 8930 176 75 55 25 9035 178 78 69 29 9340 178 81 76 35 9645 178 82 78 39 9950 180 85 82 45 10755 180 86 86 48 11160 181 89 89 51 11865 183 90 92 56 12170 183 92 104 61 12475 184 96 108 67 12880 184 98 117 78 13485 185 105 128 86 14190 187 113 146 90 14495 190 118 149 102 161

The standardised seating procedure of the BioRID IIdoes not differentiate between the driver and passenger po-sition, and the current design of the BioRID II does notautomatically adjust the backset when changing the armposition. The results of the present study show that thisstandardised seating procedure more closely resembles thedriver position than the front seat passenger position. Incomparison to the BioRID II, a 50th percentile male had an8-mm longer backset in the driver position, and a 32-mmsmaller backset in the front passenger position, while a 50thpercentile female had a 32-mm smaller backset in the driverposition and a 66-mm smaller backset in the front passen-ger position. The backset differences between the BioRIDII and the volunteers were smaller in the rear passengerposition.

There were also differences between the males and thefemales with regard to backset. Females have lower stature,and 50–70 mm shorter arms, than males [12]. This mayexplain why females chose different seat adjustments thanmales. Females sit with more upright back support, 3◦ dif-ferent from males [9]. Three degrees gives a 30–35 mmless horizontal distance at the level of the back of the oc-cupant’s head. These data might explain why females hadlower backset than the males in the front seat positions.

Seat adjustments

Table 4 shows both males and female to sit 61 and 20 mmfurther away from the steering wheel in comparison to theBioRID setting. Back rest angles for males and females are

Table 4. Seat adjustment settings. Mean values in mm and degrees for males and females and standard deviation (SD), and BioRIDsetting.

Seat adjustment BioRID Male SD Female SD

Length adjustment in (mm), 0-value is max. rearward position 140 79 44 120 46Back rest angle in (degrees), 0-value is max. reclined position of back rest 42 43 6 46 5Height rear seat cushion in (mm), 0-value is the max. lowest position 21 15 13 19 14Height front seat cushion (mm), 0-value is the max. lowest position 15 13 10 16 10

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International Journal of Crashworthiness 485

slightly more upright, 1 to 4◦. Both these settings affectbackset. A 1◦ change in the back rest angle is an approx-imately 1 cm change of the horizontal distance of the tophead restraint level.

Other findings and observations

The volunteers in this study adjusted the front seats withouthaving the head restraint in place. This resulted in an in-teresting ergonomic finding for both genders. Females withlower stature, in particular, showed negative (−) backsetvalues (driver <160 cm and front passenger position <164cm), indicating a possible conflict between ergonomic com-fort preferences and good geometric safety design. Negativebackset values were also seen for males of <173 cm in thefront passenger position.

In order to evaluate differences between drivers andpassengers, improvements could be made to the BioRIDII seating procedure to better reflect these differencesin backset. Additionally, in future development of theBioRID II, it could be of interest to see a technical featureallowing an easy adjustment of the thoracic spine shapefrom kyphosis to an erect posture without affecting the eyeposition of the manikin; this is not easily achievable in thecurrent BioRID II.

To sum up, the contributions of this study include de-tailed measurements of seated car occupants, providingknowledge of how representative the size and seating po-sition of the BioRID II dummy are, as well as input to po-tential further improvements with respect to both dummydevelopment and dummy seating procedures such as theISO [7], RCAR [13] and RCAR-IIWPG [14] protocols.

Conclusions

Human backset differed between the driver position andfront seat passenger position for both genders; this differ-ence is not reflected by the BioRID II using the standardisedseating positioning procedure. Mean backset for males inthe front passenger position was roughly half that for thedriver position and the corresponding data for females wasonly 1/3. In comparison to a local Swedish population offemale and male volunteers, sitting as drivers (hands onsteering wheels), front seat passengers (hands in lap) andrear seat passengers, the BioRID II, when positioned ac-cording to the ISO [7], RCAR [13] and RCAR-IIWPG [14]protocols, corresponds in stature to a 35th–45th percentilemale and a 96th percentile female, and in weight to a 35thpercentile male and a 69th percentile female.

Acknowledgements

The authors thank Carl-Axel Hojer for helpful assistancewith test equipment and Lotta Jakobsson and MagnusBjorklund, all at Volvo Cars, for outstanding support dur-ing the study. The study was funded by the Swedish RoadAdministration, Folksam Research, and Volvo Cars.

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