New Research Possible Thanks to Mocap Portability
New Research Possible Thanks to Mocap Portability When researchers at The Ohio State University (OSU) Sports Biomechanics Lab need to collect data on sports-related injuries, a pool of potential subjects is only a stone’s throw away. Up the stairs and down the hall is an orthopaedic clinic with plenty of patients willing to participate in a study. Test subjects provide data by walking on a treadmill in the Biomechanics Lab and get a personal gain by learning how they themselves can prevent injury or increase performance. 

Mocap Portability

Data collection could immensely improve balance issues and reduce falls in other demographic groups — like chemotherapy patients — but finding subjects is a lot more challenging than in sports medicine. For chemotherapy patients to be interested in a study, participation has to be as easy and convenient as possible. Not only are they dealing with a life-changing diagnosis, but they are most likely taking time away from family and work obligations to receive treatments. 

“We are trying to collect a lot of data to be able to share information with cancer survivors about why falls happen, characterize injuries, and identify people at risk,” says Ajit Chaudhari, associate professor of physical therapy, orthopaedics, mechanical engineering, and biomedical engineering at OSU. “We need to accomplish this all while staying as close to the cancer clinic as possible.” 

With the Stefanie Spielman Comprehensive Breast Center located across campus, Ajit and his research team can find test subjects if the motion capture lab is brought to them. This was not possible, and therefore, this study was not possible before Ajit began working with the portable Metria moiré phase tracking (MPT) system. 

“Observing how someone walks can tell us a lot about where things are going wrong in the system,” says Ajit. “Looking at various aspects of how someone walks might tell us if there is an issue with the inner ear, brain stem, soles of their feet, or something else.”

Traditional motion capture systems confine operators and subjects to a lab or studio space because upwards of eight or 10 cameras are needed for 3D motion capture. In addition, markers or reflective balls are time-consuming to place on test subjects, and data collected needs to be reviewed and hand-corrected to edit out clothing or skin movements that could be mistaken for bone or muscle. This can require careful inspection and manual labeling of each data point before any analysis can take place. 

The portable, single-camera MPT system with wire-free markers enables researchers to go onsite at the clinic and conduct data collection tests in 10 to 15 minutes, from set-up to testing, to breakdown. The single-camera system is factory-calibrated and can automatically track each marker individually and reliably. This feature eliminates the need for hand-correction of data, so data is cleaned up, analyzed, and researchers can view an animation of the bones almost immediately. 


“We chose the MPT system because of its portability but also because of the unique marker identification,” says Ajit. “In a multi-camera setup, at minimum, two cameras need to see each marker at a time in order to track movement. If a person moved in such a way that part of their body is blocking a marker, then only one camera can see it and that is as good as having no marker at all.”

The OSU research team has made great strides with cancer survivor gait analysis so far and is closer to uncovering whether balance issues secondary to chemotherapy are from damage to the peripheral nerves or to the nerves in the brain and spinal cord. The team also is gearing up for future studies with this portable, easy-to-use mocap system.

“We intend to do a study where therapists are teaching patients to walk after a spinal cord injury, and in that case, we know we will have people blocking the views in a multi-camera setup to the point where we are very concerned we would not be able to get data,” says Ajit. “Whereas with the Metria system, we only need one camera to see, and we can strategically place it for any activity line. If we set up two MPT camera systems, we will get data for entire gait cycles for both legs in one walking session.”





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