WPI Computer Science - Colloquium Announcement

Virtual Articulations for Coordinated Motion in High-DoF Robots

Marty Vona
MIT

Friday, March 6, 2009
11:00 a.m. - 12:00 p.m.
Campus Center, Hagglund Room

Abstract:

Usually we consider the kinematic topology of a robot to be immutable. What if we were to allow virtual modifications, such as adding extra joints and links? (*) These "virtual articulations" can help address several current challenges in robotics. In this talk I focus on their use as the basis for a new kind of expressive, rapid, and generic graphical interface for operating coordinated motions in robots with 10s to 100s of joints. With this interface the operator may construct virtual articulations and inter-connect them with a model of the actual robot. Virtual links represent task-relevant coordinate frames; virtual joints parametrize task motion, and, by closing cycles in the kinematic graph, constrain coordinated motions. I will show hardware results where NASA's 36-DoF All Terrain Hex Limbed Extra Terrestrial Explorer (ATHLETE) executes a variety of previously challenging coordinated motion tasks, and also real-time simulations of a revolute-jointed modular robot with over 270 joints (actual and virtual) and 90 kinematic cycles. These results are all based on a new interactive articulated robot simulator that supports dynamic and arbitrary closed chain kinematic topology with a varied catalog of joint types. I cover core challenges in handling arbitrary topology, supporting the catalog of joints, and scaling to large numbers of DoF with both convenience and speed. I introduce the idea of virtual kinematic abstraction for hierarchically managing complexity: Just as the implementation of an algorithm can be abstracted behind a compact interface, a potentially complicated kinematic sub-assembly can in some contexts be replaced by a less complex virtual stand-in. Motion for the enclosing assembly is computed using the stand-in, which then drives the abstracted sub-assembly. (*) "Links" are approximately rigid bodies (e.g. your forearm), and correspond to the vertices in a kinematic graph; joints (e.g. your elbow) are the graph edges. The degrees-of-freedom (DoF) of a joint is the dimension of its mobility space.

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Marsette Vona is a Ph.D. candidate in EECS at MIT CSAIL with Professor Daniela Rus. His current work explores theory and applications for virtual articulations in robotics, operations interface software and hardware for exploration robots, and reliable compliant/proprioceptive climbing and walking strategies. From 2001 to 2003 Marsette was a software developer at NASA/JPL, where he helped build the award-winning science operations interface for the Mars Exploration Rover mission. His 2001 M.S. in EECS at MIT was on new techniques in precision metrology for machine tools, and his 1999 B.A. thesis in CS at Dartmouth College described a self-reconfiguring robot system based on compressing cube modules.

Host: Michael Gennert

Refreshments will be served.

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Last modified: March 3, 2009