V. Patoğlu; "Force Feedback for Virtual Reality", 28.02.2007, 13:40

Faculty of Engineering and Natural Sciences
FENS SEMINARS
CS 552 Seminar

Force Feedback for Virtual Reality

Volkan Patoğlu

Unlike objects in the physical world, objects in the virtual world lack matter to “detect” and respond to collisions and to otherwise “govern” behavior. As a consequence, various models and solvers must be employed to construct virtual environments. A vital piece of enabling technology for computer animation, CAD software, and interactive virtual environments is a fast and reliable collision detector—or even better, a fast and reliable closest point algorithm. For parametric models, closest point algorithms are usually based on Newton’s Iteration, enjoy only local convergence, and possess rather touchy convergence rates. In this talk I will present a new collision detector based on a re-formulation of the closest point algorithm as a nonlinear control design problem. Control design and analysis tools allow us to solve the problem with considerable flair and to outfit the controller with attractive features like global convergence. We time-differentiated the geometric minimization problem to form the differential kinematics, then solved the inverse differential kinematics with a feedback stabilized controller. The controller selects parametric speeds that drive any pair of initialization points to the true closest points on two convex surfaces. Our design is based on a control Lyapunov function and accounts for the combined and interacting effects of object shape and object motion while achieving global uniform asymptotic stability for the pair of closest points. A top-level switching algorithm based on Voronoi diagrams extends applicability of the controller to objects made of tiled-together surface patches. Global uniform asymptotic stability of the resulting hybrid dynamical system is proved with a common Lyapunov function.

Short Bio:
Volkan Patoğlu is currently an assistant professor at Sabancý University. He received his B.Sc. degree in mechanical engineering from the Middle East Technical University. He completed his M.Sc. degrees in mechanical engineering and electrical engineering – systems at the University of Michigan, Ann Arbor, where he also received his Ph.D. degree in mechanical engineering. He worked as a post doctoral research fellow in Haptix Laboratory at the University of Michigan and as a post doctoral research associate in Mechatronics and Haptic Interfaces Laboratory at Rice University. His research interests include nonlinear control, automated modeling and physically-based simulation of hybrid dynamical systems with applications to haptic rendering. His research also extends to modeling human neural mechanisms during motor skill acquisition and exploiting these models to improve effectiveness of rehabilitation and motor skill training.

February 28, 2007, 13:40, FENS L056