Thursday, September 27, 2012

Bicycling injuries represent a significant public health concern in the United States. According to the National Highway Traffic Safety Administration, 51,000 bicyclists were injured in motor vehicle traffic crashes in 2009; about 8,000 (17 percent) of the cyclists who were injured were age 14 and younger. 

University of Iowa graduate students and faculty in computer science, informatics, and psychology are working together to examine the factors that put children at risk for bicycle-motor vehicle collisions when crossing traffic-filled intersections. They conduct their research using the UI’s Hank Virtual Environments Lab bicycle simulator

“We put children in situations where there is real-world danger, but here they can’t get hurt,” says Elizabeth O’Neal, a Ph.D. candidate in psychology. “I look at the behavior that causes children to cross unsafely. I use this virtual reality to study injury prevention.” 

The Hank Virtual Environment’s Lab promotes the use of virtual environment technology to advance the field of behavioral science and computer science through a study of human behavior in real and virtual environments. According to the lab’s website, five- to 15-year-old children represent a particularly vulnerable segment of the population, having the highest rate of injury per million cycling trips. 

An interdisciplinary approach

In this interdisciplinary research, psychology and computer science students collaborate. The psychology students develop the testing parameters for real-world scenarios, which are rendered as virtual environments by their computer science colleagues. 

Cycling simulation software is large, complex, and multifaceted. An intimidating range of problems must be addressed in order to create these virtual environments: visual scene creation, modeling behavior of vehicle drivers, bicycle dynamics simulation, road database management, scenario control, and real-time coordination between several computers involved in the simulation. 

“Our goal is to make this computer-generated world to feel real for the rider,” says Timofey Grechkin, a Ph.D. candidate in computer science. “We need to make sure the virtual world is similar to the real world to insure the psychological experiments produce valid results. The important question is do the people behave the same way in the virtual environment and the real world?” 

The simulator

Participants jump onto a bicycle equipped with instruments to record the steering angle of the front wheel and the speed of the rear wheel. Steering angle and wheel speed measurements are combined with virtual terrain information to render the graphics corresponding to the rider’s real-time trajectory through the virtual environment. 

The riders pedal through a virtual city—complete with stop signs at intersections and traffic speeding by—displayed by rear projectors on three 8-foot-tall, 10-foot-wide screens placed at right angles relative to one another, forming a three-walled room. 

As the adolescent participants ride on this virtual street, a computer records the rider’s decisions and reaction times at intersections. Graduate students later analyze the data and compare it with the behavior of children and adults. 

Researchers say between 200 and 300 children from Johnson and Linn counties enter the simulator annually to participate in research studies. 

"Children and adults both choose a safe gap between cars through which to cross the road, but children have more problems coordinating their actions with their perception in order to safely cross through the gap,” says Christine Ziemer, a Ph.D. candidate in psychology. 

The research team

Jodie Plumert (professor of psychology), Joe Kearney (associate dean of the College of Liberal Arts and Sciences and professor of computer science), and Jim Cremer (professor of computer science) collaborate to lead the bicycle simulator research, which is funded through grants from the National Science Foundation, the National Institutes of Health, the Centers for Disease Control and Prevention, and the University of Iowa’s Injury Prevention Research Center. 

“There is a level of sophistication in this complex interdisciplinary research that the students wouldn’t have in other places,” Kearney says. “You see what it’s like to be in your fellow researchers’ shoes. You work through problems and find solutions collaboratively.” 

The research team is currently constructing a second bicycle simulator that features larger screens than the existing simulator and uses projectors capable of displaying three-dimensional stereoscopic images, similar to what you see in a 3D movie theater. 

Both simulators will reside in MacLean Hall, with the new model expected to be operational this fall. The simulators will be linked, allowing researchers to study two people riding side by side. The participants will be able to see each as digital avatars within their virtual environments and communicate through headsets. 

Megan Mathews, an M.S. candidate in the Interdisciplinary Graduate Program in Informatics, is designing the avatars. 

“We’re hoping to connect our new simulator with our current simulator so that we can observe what happens when two friends or a parent and a child ride together,” says Mathews, who researches social interaction and rider behavior. “I am hoping to create an avatar that has enough realism to be believable. By incorporating Hollywood techniques such as motion capture, we can communicate real-time movements so that the avatar is more human-like.”