Comparison of Malaysian and SAE J833 Anthropometric Proportions for Vehicle Package Design

Anthropometric measurements are critical dimensions when considering human interface design. This is especially true in vehicle package design where the interaction of the drive with the vehicle interior components need to be precisely determine as a mismatch between them would not only be detrimental to the drives comfort but driving performance and safety as well. In the past car makers often depends on standard databases derived from population that are not necessarily suited to the local population. Among the key concerns are the anthropometric measurements values and body ratio which would drive the design requirements of the vehicle package. Thus this paper describes the study which has been done to understand Malaysian Anthropometry in comparison of current available databases. The results shows significant differences in body proportion which may lead to the necessity to further study the effect of this differences.


Introduction
The measurements of the human body, also known as anthropometry, are essential in the ergonomic design of products and workplaces. Since natural postures and movements are based on the dimensions of the torso, arms and legs, it is essential that the workplace should be suited to the body size of the operator. (Grandjean 1988). Herron (2001) defined anthropometry as the study of human body measurements which has a significant role in the construction of a functional humanmachine interface. The human machine interface can be categorized into three different parts; the human operator, the equipment (hardware and software) and the working environments (physical and psychosocial). The person performing the task would also vary because of the variations in physical features size, shape and strength.
There are several factors causing significant variations in human body sizes. The two main variations in body size between individuals are attributed to the gender and race of the person (Kianoush Fatollahzadeh, 2006). Hence, many countries have made the effort in establishing localized anthropometric databases for different population groups such as for civilian, military personnel, students and workers. According to Pheasant (1996), the variations of body dimensions of different groups can be observed in terms of overall body size and bodily proportions. The means anthropometric dimensions, for example stature and sitting heights, are the most typical distinctions among ethnic groups. Another significant ethnic difference is in the bodily proportions, which are the ratios of body dimensions. Bodily proportion is a scaling relation obtained from the calculated ratio of one body dimension to a specific reference dimension. (Yu Cheng Li et al 2004) The study by Yu Cheng et al. (2004) has found that there are significant differences in means body dimensions and bodily proportions of the people in East-Asia, such as the Japanese, Chinese, Korean and Taiwanese, even though they are from the same region. For example, the Chinese tend to have narrow torso with moderate limbs while the Japanese have a wider torso and shorter limbs. The Korean have a moderate body shape within the group but the upper limbs are longer than the rest. The Taiwanese have wide shoulders and narrow hips with large hands and long legs.
In vehicle package design, vehicle designers would often refer to the SAE (Society of Automotive Engineers) Standards, which is based on a two-dimensional accommodation tools to design various vehicle components. The Standards includes details of the human dimensions or anthropometry, seating positions, reach envelopes, head contours and eye ellipse (Roe,1993). Examples of SAE Standard are SAE J1517 (Driver Selected Seat Position) and SAE J826 (Devices for Use in Defining and Measuring Vehicle Seating Accommodation). These standards were developed based on the U.S Army population (Gordon et.al.1989).
However, caution is necessary when utilising such standards as guidelines for vehicle package designs. Since the SAE standards are based on data collected in 1960's, there may have been changes to anthropometry of the population. Furthermore, according to Scott A Ziaolex PK .et al (2004), Standards based on a database of North American population could not be directly applicable to Asian population. In fact utilising a region specific database for other world regions would generally cause problem. (Nag PK .et al (2004).
Thus, the objective of this research is to compare the existing SAE Anthropometry data with a collection of anthropometric measurements based on the Malaysian population. The comparison of body segments in various vehicle design package configurations would also be analysed.

Methodology
The anthropometric measurements were adapted from three standards which were SAE J833 Human Physical Dimension, ISO 3411: 2007 Earth Moving-Physical Dimension and CATIA V5 Human Builder Population. Based on these standards, 105 parameters were identified and selected to build the human manikin in CATIA Human Modelling software. The 105 anthropometric measurements selected in this study is shown in which 23 measurements are discussed in this study. The anthropometric measurements follows the definition as prescribed by . Gordon et. al (1989).
A random sampling of 210 human subjects was chosen and their anthropometric measurements taken using manual measurement methods as described in the ISO standard. The measurements comprised of both standing and sitting anthropometric dimensions. The number of sample was determined based on convenience sampling. The subjects consisted of 105 males and 105 females with an age range of 17 years to 60 years old. Although the majority of the subjects were residing in the Lembah Pantai area, many were originally from different parts of the country. Due to this variability, the data collected is assumed to be representative of the Malaysian population. From the 105 measurements, 23 anthropometrics dimensions consisting of 11 standing measurements and 12 sitting measurements were selected for comparison with other anthropometric databases. Comparison was made with the SAE J833 database for both male and female anthropometric data as listed in SAE Standard Human Physical Dimension table (SAE J833) based on 5 th Female, 50 th Male and 95 th Male percentiles. The SAE J833 were established based on the data of United States population (SAE J833, 1989). The body ratio of the anthropometric measurements and stature were also calculated for all 23 selected anthropometric measurements.
Advanced Engineering Forum Vol. 10 Table 1 shows the comparison of the selected standing measurements, as depicted in Figure 1, between the collected data and those of the SAEJ833. Whereas Table 2 compares the sitting measurements, as depicted in Figure 2, between the two databases. The comparison of the data in both Table 1 and Table 2 shows significant differences in all of the anthropometric measurements. However, the ratios of anthropometric measurement-to-stature for almost all of the selected measurements are consistent when compared to the SAE J833 database.    For Sitting Stature dimensions, as shown in Table 2, the SAE J833 data depicting the North American population has longer or higher body segments as compare to Malaysian population except for three body dimensions which are Shoulder height, Thumbtip reach and Foot width. The Shoulder width is higher as compared to SAE J833 by 13% or 86.4mm in the 95 %tile Malaysian male, 14% or 85.4mm for 50% tile male. However, the 5 %tile Malaysian female and SAE J833 data are equivalent. For Thumbtip reach, the 95 %tile Malaysian male is slightly longer by 0.8 % or 7 mm and for the 50 %tile male is it 2.4% or 18.5mm longer than its equivalent in the SAE J833. However, the 5 %tile Malaysian female is shorter by 4.1% or 28mm. For the foot width dimension, Malaysian 95% tile male is wider by 5.4% or 6 mm while the 50 %tile male is also wider by 4.6% or 4.6mm as compared to the SAE J833. However, the 5 %tile Malaysian female is shorter by 3.2% or 2.7mm. Figure 3 shows the comparison between SAE J833 and Malaysian population as depicted by manikins built from their respective population data. In Vehicle Package design, there are several key parameters for consideration in driver cockpit space design. The Society Automotive Engineering (SAE) has recommended several guidelines which have been globally adopted by numerous automotive manufacturers (Roe, RW 1993, Society of Automotive 1998,Matthew P. Reed, et., al 1999). These parameters include the SAE J287 (Driver Reach -hand reach), SAE J941 (Driver Eyellipse -Eye location), SAE J826 (H-Point manikin), SAE J1052 (Head Position -Head Clearance) , SAE J1517(Driver Selected Seat Position -seat adjustment ), as shown in Figure 4. Other importance parameters such as the Shoulder room, Legroom, vision, reachability, clearances should also be considered for driver cockpit ergonomics.

Results and Discussion
The findings have shown that there are slight significant differences between the standard Human Dimension of SAE J833 (North American population) and the Malaysian population. In general, data from SAE J833 indicated longer dimensions on lower body segment which is from the

Current Trends in Ergonomics
hip to the bottom leg whereas the Malaysian population has longer dimensions on upper body segment including trunk length and arm length.
Due to these differences, there is a possibility of mismatch between vehicle package design based on SAE J833 data with those of the Malaysian population, especially on the reachability aspect to steering and pedals that influence the total body comfort posture. In addition, the hip point and eye-hip point are two key hardpoint that should be considered in determining the position and posture of the driver in driver cockpit area.

Figure 4 : SAE Recommended Standard Practise in driver cock-pit
A Pearson product-moment correlation coefficient analysis shows negative high correlations for Malaysia manikin on steering and pedals to lower body segment and high positive correlations on seating to eye height in passenger driver cockpit, as shown in Table 3. Therefore, in designing the driver cockpit area of a vehicle for the Malaysian population using SAE Standard design practices, specific countermeasures should be considered on the on seat, steering or pedals parameters to minimize the gaps of the body dimension to account for the variation between the Malaysian and the North American population (from which the SAE J833 is based) Those specific countermeasure may include multiple seat adjustments (fore-aft and seat height range), adjustable steering system in the form of the telescopic steering type or the possibility for adjustable pedals to accommodate different body segments.
The results from the findings of this study agrees well with previous research on driver's posture, that there is difference in postural angle between Malaysia, Korea and Caucasian (which included North American) populations due to differences in anthropometric characteristics. (Darliana et.el.,2010). Figure 5 shows the comparison of driver position in driver cockpit space for Malaysia and SAE J833 in area of reachability (steering and pedal ) and front visibility . Figure 6 shows that, due to the difference of hip point or seating position for the smallest manikin (5%tile female Malaysia) and the biggest manikin (95%tile male SAE J833), there is a requirement for seating adjustment (fore-aft and height) to meet the hip point distance and eye height distance as countermeasure for reachability and front vision of the driver.

Conclusion
Generally, it was shown that the Malaysian population is shorter as compared to the SAE J833 standard. The comparison has shown that the Malaysian population is shorter by 6.5 % or 83 mm for 95 %tile male, 1.1 % or 18 mm for 50 %tile male and 7.3 % or 70 mm for 5 %tile female as compared to the SAE J833 dimensions. However, there are several body segment dimensions in which the Malaysian population has slightly higher or longer dimensions as compared to SAE J833. These dimensions are the trunk height, trunk length, forearm, shoulder dimension (shoulder width and shoulder height) and slightly wider on foot width. Thus, for region specific vehicle package designs, these variations in dimensions should be considered, especially in areas related to reachability and vision. The results from this study can be utilized for the ergonomic design of vehicle cockpit especially suited for the Malaysian population.