Exploiting quaternions to support expressive interactive character motion

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Includes bibliographical references (p. 261-266).A real-time motion engine for interactive synthetic characters, either virtual or physical, needs to allow expressivity and interactivity of motion in order to maintain the illusion of life. Canned animation examples from an animator or motion capture device are expressive, but not very interactive, often leading to repetition. Conversely, numerical procedural techniques such as Inverse Kinematics (IK) tend to be very interactive, but often appear "robotic" and require parameter tweaking by hand. We argue for the use of hybrid example-based learning techniques to incorporate expert knowledge of character motion in the form of animations into an interactive procedural engine. Example-based techniques require appropriate distance metrics, statistical analysis and synthesis primitives, along with the ability to blend examples; furthermore, many machine learning techniques are sensitive to the choice of representation. We show that a quaternion representation of the orientation of a joint affords us computational efficiency along with mathematical robustness, such as avoiding gimbal lock in the Euler angle representation. We show how to use quaternions and their exponential mappings to create distance metrics on character poses, perform simple statistical analysis of joint motion limits and blend multiple poses together. We demonstrate these joint primitives on three techniques which we consider useful for combining animation knowledge with procedural algorithms: 1) pose blending, 2) joint motion statistics and 3) expressive IK. We discuss several projects designed using these primitives and offer insights for programmers building real-time motion engines for expressive interactive characters.by Michael Patrick Johnson.Ph.D

Torsional eye movements in humans

If one has to give a description of eye movements, what first comes to mind is the possibility of the eyes to rotate in horizontal and vertical directions. It is generally less obvious that the eyes are capable of moving in a third. namely the torsional. direction. This capability is by no means hypothetical: humans, as well as other species, possess eye muscles that are pulling in torsional direction and orbital mechanics do allow for a certain amount of torsion. Definition of torsion Torsional eye movements can be defined in two different ways, namely as a rotation about the line of sight and as a rotation about an antero-posterior (forward-to-backward) axis that is fixed in the head

Design and implementation of a multiprocessor system for position and attitude control of an underwater robotic vehicle

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1990.Includes bibliographical references (leaves 115-116).by Ella Marie Atkins.M.S

1999 Flight Mechanics Symposium

This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on May 18-20, 1999. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers

NASA Tech Briefs, October 1995

A special focus in this issue is Data acquisition and analysis. Topics covered include : Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; and Mathematics and Information Sciences. Also included in this issue are Laser Tech Briefs and Industry Focus: Motion Control/ Positioning Equipmen

Aeronautical engineering: A continuing bibliography with indexes (supplement 308)

This bibliography lists 269 reports, articles, and other documents introduced into the NASA scientific and technical information system in Sep. 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics