Motion Capture Using Personal Area Wireless Networks

An expert in cutting the cord, Gustavo Vejarano, assistant professor of electrical engineering and computer science, is studying applications of wireless technologies. Vejarano is researching networks of wireless sensors to overcome the limitations of infrared-based motion capture systems.

“There’s a need for wireless connectivity so we can communicate our experiences for different types of purposes,” he explained. “It could be entertainment, it could be health. Wireless technologies can penetrate walls, so they can be present at many locations without having to deploy infrastructure within every single room.” In his research, “We attach wireless sensors to the user with watch straps. Then we monitor their movements. We can determine joint angles, such as shoulder and elbow. That information is sent [wirelessly] to the computer, which makes decisions based on those variables. For example, people can generate sounds from a synthesizer according to the movements they are making. Also, some of our students are using this system to monitor the progress of physical therapy patients, so they can make sure the patient is performing the exercises correctly.” There are different technologies for motion capture, and infrared-based motion capture systems, which are already in wide use, have limitations.

“There are advantages and disadvantages to each of the technologies,” Vejarano continued. “Infrared can be blocked by a wall. Wireless can’t. Infrared has problems working outdoors because of the sunlight. That’s not the case for the wireless sensor.” However, infrared systems are more accurate than the wireless sensors.

“Another contribution we’re making is the modeling of the effects of skin and muscles on the measurements of the wireless sensors,” Vejarano said. “The relatively random movements of the muscle and skin affect the measurements.” If we can model those effects on the measurements, we can improve the accuracy. This is something that has not been researched in detail.”