[PAST] Design Involving Many Links: Shape-Changing Mechanisms in Dies and Morphometry, Infinity Chains, and Statically Equivalent Serial Chains
[PAST] Design Involving Many Links: Shape-Changing Mechanisms in Dies and Morphometry, Infinity Chains, and Statically Equivalent Serial Chains 
2015 / 11 / 06 / AM 11:00
Location: 301 - 1420
Speaker: Professor Andrew P. Murray
Noting that simplicity in operation is always the goal, research in the Design of Innovative Machines Lab (DIMLab) seeks to effectively synthesize complicated systems of rigid bodies when required by the design challenge. Four topics will be covered. The first topic is designing shape-changing devices that combine basic components into sophisticated machines. Designs include shape-changing spoilers, wings, seats, cams and parabolic light reflectors. The National Science Foundation has funded shape-change under the project on designing variable geometry dies for polymer extrusion. A host of parts, from PVC tubing to weather stripping to artificial lumber for decking, is made by extrusion. Extrusion is so valued because it is inexpensive and fast when compared to molding, the other primary way of making plastic parts. So why aren¡¯t more parts extruded instead of molded? Every extrusion has a constant cross-section. A variable geometry die allows the cross-section to vary. We are developing the algorithms to design these dies and have now prototyped and tested a variety of examples. The second topic is to use rigid-body shape-change in morphometry, the quantification of changes in shape. Morphometry is frequently used to study changes due to evolution and growth. Shape-change is used to explore the morphometry of skulls and cochlea as they grow. The third topic is an algorithm that allows mechanisms to grow to an arbitrary number of links to produce any periodic function. In most cases, the mechanisms include dozens of links, where the action of any one of the parts affects the motion of all others. These mechanisms captivate the imagination yet possess almost no capacity to be designed and built. The final topic is the rapidly determining and accurately tracking the center of mass (CoM) of a human or humanoid. A Statically Equivalent Serial Chain (SESC) can be built from a modest amount of force plate and motion capture data. With the SESC, the force plate is no longer needed to track the CoM of a human or humanoid.
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 2008. Please visit academic.udayton.edu/DIMLab to learn more about the research.