3D Motion Capture and Electromyography

Optically-based 3D motion capture systems use reflective markers attached to key anatomical features on the subject of interest.  The reflective markers are tracked by multiple video cameras and (after proper calibration of the camera positions, camera lens distortion, subject's anatomical features, etc.)  highly specialized software automatically calculates the 3D positions of the markers using the techniques of triangulation.  The marker positions are then used to estimate the skeletal kinematics (joint centers and axes of rotation) of the subject wearing the markers.

 

Surface electromyography (SEMG) is widely applied to characterize the time phasing of muscle activity.  Electrodes attached to the surface of the skin over the muscle(s) of interest enable measurement of the electrical activity associated with muscle contractions.  The electrical signals typically document the activity or inactivity of muscles over time as well as the relative degree of activity compared to a previously determined standard (e.g., an isometric maximum voluntary contraction). 

 

Auburn University's new 6 camera motion capture system from Motion Reality Inc, (Atlanta, GA) and 8 channel wireless EMG system from Noraxon Inc. (Scottsdale, AZ) are currently being used in biomechanical engineering studies of precision motor skills, balance and force generation during complex motion.  For example: