报告时间：12月13日（星期五）19:00
报告形式：教一楼二阶
报 告 人：Andres Kecskemethy，德国杜伊斯堡-埃森大学（University of Duisburg-Essen）教授
报告题目：Projection methods for 3D rotations and their application to robotic-mechanisms and biomechanics dynamics
内容简介：Spatial rotations are - as is well-known - non-commutative continuous (Lie) groups and can thus not be represented as vector spaces. This makes the problem of “projecting” the three-dimensional space of rotations to two dimensions, such as needed sometimes for example to remove a rotation about a given natural direction or to extract a rotation component in a given natural direction, complex and of not unique solution, in contrast to vector space, where such projections are always unique. In this lecture, the different approaches in the literature to carry out such “projections” (such as Euler angles or coordinate-axes projections) is reviewed, and their properties for different test scenarios are analyzed. As it turns out, results depend very strongly on the sequence of rotations, and surprisingly, the coordinate-axes projection and the Euler angle extraction can be associated one-to-one to each other. In the lecture, a new “projection” method based on Quaternion or Euler-Rodrigues parameter representation is presented, which is shown to be coordinate independent and directly related to the rotation space. The methods are visualized and validated by numerical experiments as well as camera-based tracking of cuboids. In this respect, a new method is proposed to identify the 3D rotation matrix of a cuboid via projections of the edges to two camera planes, yielding more precise results than the cuboid orientation-matrix determination using classical single-camera algorithms such as built-in in Matlab. As application of 3D rotation “projections” respectively extractions, the determination of flexion/extension angle at the knee from 3D inertial measurement units (IMUs) at thigh and foreshank as well as the efficient dynamic modelling of a parallel platform with moving base are presented. It is shown that the coordinate-invariant extraction respectively “projection” of 3D rotations lead to more precise results when compared for example to Vicon and also fast and precise term reductions in multibody dynamics.
报告人简介: Professor Kecskeméthy was born in Lima, Peru and graduated from the University of Stuttgart in Mechanical Engineering in 1984, receiving his Ph.D. in Mechanical Engineering from the University of Duisburg in 1993. From 1994 to 1995, he stayed as a senior guest researcher at the Centre for Intelligent Machines at McGill University with a fellowship from the German Research Foundation (DFG). In 1996, Dr. Kecskemethy was appointed Professor at the Technical University of Graz, where he held the Chair for Mechanics until 2002. In 2002, Professor Kecskeméthy moved to the University of Duisburg-Essen, where he holds the Chair for Mechanics and Robotics at the Institute of Mechatronics and System Dynamics. He was bestowed with the Doctor honoris causa from Riga Technical University on 2018. He was Editor-In-Chief of the Journal Mechanism and Machine Theory from 2004 to 2015. He served as Dean of the Faculty of Engineering and as Chairman of the Senate of the University Duisburg-Essen. His memberships include the International Federation for the Promotion of Mechanism and Machine Science IFToMM. Since 2013, he was Chair of IFToMM MO Germany, and since 2020 he is IFToMM President for the term 2020-2023. Professor Kecskeméthy has worked in the areas of kinematics and dynamics of multibody systems, covering topics such as modelling and control of mechatronic systems, vehicle dynamics, design of legged machines, biomechanics, virtual reality as well as medical and heavy-weight robotics. He received, apart from three best-paper awards, several institutional awards such as the Award of the University of Minho for Scientific Cooperation, the ASME Design Engineering Division Mechanism and Robotics Award, the Award “Illustrious Scientist of the Ibero-American Association of Mechanical Engineers”, the IFToMM “Dedicated Services Award” and two Best Teacher Awards. He has organized several international conferences [IAK 2008, IAK 2013, IAK 2018, Computational Kinematics 2009, ECCOMAS Multibody Dynamics 2019, International Symposium on Theory and Practice of Robots and Manipulators (ROMANSY) 2022, Advances in Robot Kinematics (ARK) 2022], and is the author of more than 230 proceedings and journal papers.
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