Identifying the center of mass (CoM) of an articulated system, a human or humanoid for example, is important due to its roll in stability and as a gauge of motion for the entire system. As such, precise determination of the CoM is useful in improving balance control algorithms in humanoids and in measuring the effectiveness of physical therapies in humans. The statically equivalent serial chain (SESC) is a tool under development for locating and tracking the CoM. Any articulated system of rigid bodies defines a SESC, a virtual chain that terminates at the CoM of the original system of bodies. A SESC may be generated experimentally without knowing the mass, CoM, or length of the links in the system given that its joint angles and the projection of the overall CoM may be measured. This allows for the development of a SESC in a subject-specific way, without the need for anthropometric tables, and without need for a force plate to track the CoM. This presentation will show the development of the SESC concept and apply it to humans by showing the results of experiments in locating and tracking the CoM.
Andrew Murray received the B.S. degree in mechanical engineering from the Rose-Hulman Institute of Technology in 1989, and the M.S. and Ph.D. degrees in mechanical engineering from the University of California, Irvine in 1993 and 1996, respectively. In 1997, he joined the Department of Mechanical & Aerospace Engineering at the University of Dayton as an Assistant Professor, became an Associate Professor in 2003, and a Professor in 2011. He is a Director of the Design of Innovative Machines Lab (DIMLab) where the research in kinematic synthesis theory and machine design includes shape-changing mechanisms with applications in variable geometry extrusion dies, novel devices that utilize strain-energy in automobiles, and accurate estimation and tracking of the center of mass of complex systems. He also has a long-standing collaboration with researchers at the Laboratoire d’Informatique, de Robotique et de Microélectronique in Montpellier, France. Dr. Murray is a Fellow of ASME. He won the highest teaching award offered by his university in 2013. He was General Program Chair of the ASME International Design Engineering Technical Conferences in 2010 and has served as an Associate Editor for the ASME Journal of Mechanisms and Robotics since it was founded in 2007.