Masters Degrees (Mechanical and Mechatronic Engineering)

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Browsing Masters Degrees (Mechanical and Mechatronic Engineering) by Subject "3D human kinematics"

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    An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics
    (Stellenbosch : University of Stellenbosch, 2011-03) Cockcroft, Stephen John; Scheffer, C.; University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high sample rates. One of the limitations of these systems is that they can only be used indoors. However, advances in inertial sensing have led to the development of inertial Mocap technology (IMCT). IMCT measures kinematics using inertial measurement units (IMUs) attached to a subject's body without the need for external sensors. It is thus completely portable which opens up new horizons for clinical Mocap. This study evaluates the use of IMCT for improving road cycling kinematics. Ten male sub-elite cyclists were recorded with an IMCT system for one minute while cycling at 2, 3.5 and 5.5 W.kg-1 on a stretch of road and on a stationary trainer. A benchmark test was also done where cycling kinematics was measured simultaneously with the IMCT and a gold-standard Vicon optical system. The first goal was to assess the feasibility of conducting field measurements of cycling kinematics. Magnetic analysis results showed that the IMUs near the pedals and handlebars experienced significant magnetic interference (up to 50% deviation in intensity) from ferrous materials in the road bicycles, causing significant errors in kinematic measurement. Therefore, it was found that the IMCT cannot measure accurate full-body kinematics with the subject on a road bicycle. However, the results of the benchmark test with the Vicon showed that the IMCT can still measure accurate hip (root mean square error (RMSE) < 1°), knee (RMSE < 3.5°) and ankle (RMSE < 3°) flexion using its Kinematic Coupling algorithm. The second goal was to determine whether there is a significant difference between road cycling kinematics captured on the road and in a laboratory. The outdoor flexion results were significantly different to the indoor results, especially for minimum flexion (P < 0.05 for all joints). Changes in rider kinematics between high and low power were also found to have significantly more variability on the road (R2 = 0.36, 0.61, 0.08) than on the trainer (R2 = 0.93, 0.89, 0.56) for the hip, knee and ankle joints respectively. These results bring into question the ecological validity of laboratory cycling. Lastly, applications of IMCT for optimizing cycling performance were to be identified. Several aspects of kinematic analysis and performance optimization using the IMCT were evaluated. It was determined that IMCT is most suited for use as a dynamic bicycle fitting tool for analysis of biomechanical efficiency, bilateral asymmetry and prevention of overuse injuries. Recommendations for future work include the elimination of the magnetic interference and integration of the IMCT data with kinetic measurements to develop an outdoor dynamic fitting protocol.