>>> Research: Anthropometry
Anthropometry of Motor Vehicle Occupants
During the 1980s, UMTRI researchers conducted a landmark study of driver posture and anthropometry for crash dummy design. Known as the Anthropometry of Motor Vehicle Occupants (AMVO) study, the research produced data are currently the standard representations of small-female, midsize-male, and large-male vehicle occupants. Data and reports from AMVO are available on my downloads page. In the years since the AMVO project, UMTRI researchers have applied related methods to dozens of studies of vehicle occupant anthropometry. These studies constitute "functional" anthropometry in the sense that the goal is to characterize the size and shape (posture) of the body in a task-oriented context. Here, the context is normal vehicle sitting. Many of the applications for these data are related to the development of tools for vehicle interior design, but the data also have applications to crash dummy design and other safety applications. Most of the UMTRI studies have been conducted in light-vehicle environments (passenger cars, light trucks, SUVs, minivans), but several studies have addressed drivers of heavy trucks.
Adult Anthropometry
We pioneered the use of the FARO Arm coordinate digitizer to record human postures by measuring the 3D locations of body landmarks. Previously, UMTRI studies were conducted using stereophotogrammetry or sonic digitizers. The FARO Arm technique provides accurate data on body landmark locations that are difficult to obtain using optical marker systems. We've developed methods to estimate internal joint locations based on surface landmarks and we use the resulting joint locations to define posture based on a kinematic linkage representation of the body. We use a hardseat to that provides access to both anterior and posterior torso landmarks. A subject-specific torso model based on the hardseat data is used to estimate torso joint locations for test conditions in vehicle seats, for which only anterior landmarks are available.
We conduct studies both in the laboratory and in vehicles. A typical laboratory study uses a partial vehicle mockup, often just a seat, pedals, and steering wheel. Depending on the study objectives, we might use different seats or change the steering wheel position to quantify their effects on posture. We record seat belt routing with respect to the shoulder, sternum, and pelvis, and use the FARO Arm to capture stream data spanning these critical interface areas.
Child Anthropometry
The best available anthropometry data for U.S. children were gathered by an UMTRI team during the 1970s. These data have limited utility for vehicle applications because the standard anthropometric postures are dissimilar in important ways from the postures children use in vehicles. We conducted a study of 68 children from 40 to 100 lb sitting in a variety of vehicle- and booster-seat conditions to quantify the children's postures. We gathered data on torso dimensions, particularly depths and breathds, to provide more relevant data for crash dummy design. In general, children's vehicle-seated postures are more slumped than the fully erect postures measured in the standard anthro surveys.
Body Shape Modeling
The conduct of anthropometric surveys has changed substantially in recent years due to the availability of whole-body scanners that can capture three-dimensional body shape. The best-known U.S. survey is the CAESAR study conducted by the U.S. Air Force and SAE, but other surveys, including SizeUSA, have included a scanning component. I've been working with the CAESAR data since the beginning of the program, with a primary focus on modeling torso shape. This work has been conducted for Herman MIller, a major office furniture manufacturer. I've developed software to extract the torso data from the scan files and to articulate the torso with smooth surface deformation. Using principal component analysis and multivariate regression, I've created a statistical model that generates torso shapes based on overall anthropometric variables, such as gender, stature, and body weight. Herman Miller uses the tools developed from these analyses to improve their office chair designs.
Modeling Skeletal Components from CT Data
My colleagues and I have applied anthropometry methods developed for external data to the modeling of skeletal structures for application to human modeling and crash dummy design. Most finite-element models of the human body used for crash simulation are based on a single specimen, usually the Visible Human. More useful simulations could be conducted using parametric models of body structures that captured the variation across individuals. Similarly, crash dummy pelves have typically been constructed by scaling X-ray data from a few individuals, or using manual measurements from skeletal pelves. The pelves of the Hybrid-III 6YO and 10YO dummies are based on scaling of the adult Hybrid-III pelvis to match pelvis-width data from standard anthropometric surveys. Because the geometry of the pelvis is an important component of overall dummy biofidelity, we have developed a new model of the child pelvis based on CT reconstructions. We used ImageJ software from NIH (kudos to Wayne Rasband for a fantastic program), OsiriX (another fantastic open source program for processing medical imaging data), and custom software I wrote in Mathematica to generate detailed surface meshes for over 100 child pelves (ages 4 to 12). A statistical analysis based on principal components was used to generate "average" pelves for the 6YO and 10YO crash dummies.
©2007 Matthew P. Reed