Motion Tracking of Highly Dynamic Multi-Link Systems in Unconstrained Space

Author: ORCID icon
Cox, Jeronimo, Mechanical and Aerospace Engineering - School of Engineering and Applied Science, University of Virginia
Furukawa, Tomonari, EN-Mech & Aero Engr Dept, University of Virginia
Kent, Richard, EN-Mech & Aero Engr Dept, University of Virginia
Russell, Shawn, MD-ORTP Ortho Research, University of Virginia

This thesis presents a motion tracking methodology for highly-dynamic, multi-link systems unconstrained by space due to visual obstruction or magnetic distortion. The proposed technique of dynamic measurement fusion changes the role of the accelerometer from correcting inclination with the gravity vector only in quasi-static motion, to measuring centrifugal forces of links. This allows measuring angular rate of links not only with gyroscopes embedded to \gls{imu}s, but also accelerometers, making more use of the inertial sensors. Headings of links are corrected with magnetometers. As local distortion is inconsistent at every position in some space, a method is proposed to measure local hard iron distortion, allowing heading correction to be more effective in nonuniform magnetic fields. In validating the techniques using an experimentally induced two degree of freedom motion, error in estimated state has improved by half an order of magnitude. While the methods have worked to track highly dynamic humanoid motion, the proposed technique has difficulty estimating quasi-static 3D motions.

MS (Master of Science)
Motion Tracking, Sensor Fusion, Extended Kalman Filter, Magnetometer, Real-time Calibration
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