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On the implementation of opensim: applications of marker-based and inertial measurement unit based systems

Biçer, Meti
The gait analysis system of METU Mechanical Engineering Department was established in the mid 1990s. The measurement technique is based on capturing the marker locations by means of video-cameras. The software packages employed are responsible for processing of video-camera images to obtain the 3-D positions of markers attached to specific locations of body and inverse kinematics and dynamics to reveal the joint angles, forces and moments during a gait. The first goal of the study is to analyze alternative methods of obtaining joint kinematic parameters from the marker locations by implementing different rotation angle sequences. The results indicate that, for a typical gait, different rotation sequences do not cause severe differences in the joint angles. Additionally, an open-source software, OpenSim, is utilized to process marker data, which provides a simulation environment for the existing system. Different skeletal models are created and critically analyzed with the aid of OpenSim. The last part of the study is devoted to the development of a new system using inertial measurement units. Each inertial measurement unit attached to body segments is responsible for extracting the orientation of the body in 3-D. The joint kinematic parameters and simulation are handled employing OpenSim, through subroutines written using its libraries.