Woodruff School of Mechanical Engineering


Control of Underactuated Robotic Systems: Rolling Sphere to Synthetic-Wheel Biped


Dr. Ranjan Mukherjee


Michigan State University


Wednesday, December 5, 2012 at 3:00:00 PM


MRDC Building, Room 4211


Henrik Christensen


Dynamical systems with fewer control inputs than the number of generalized coordinates are commonly referred to as underactuated systems. Examples of such systems are the pendubot, the acrobot, and point-feet biped robots, which are subjected to second-order differential constraints; as well as nonholonomic systems, which are subjected to first-order differential constraints. In this presentation, the stabilization problem of the rolling sphere will be discussed first. There are many open-loop solutions for reconfiguration of the rolling sphere but few results on feedback stabilization. The stabilization strategy to be presented exploits the singularity of a specific Euler angle representation and relies on motion primitives of the sphere that are circular arcs and straight-line segments. A video of a spherical robot, designed in-house, navigating a hallway will also be presented. The dynamics of the spherical mobile robot motivated the design of a “synthetic-wheel” biped and the second half of the presentation will focus on gait and control design of the biped. The need to incorporate impulsive forces in control of underactuated systems will be motivated using experimental results of the biped. The presentation will wrap-up with experimental results from ongoing work; this includes swing-up control of the pendubot using impulsive control inputs and a novel underwater vehicle that uses a fluid-conveying fluttering tail for propulsion.


Ranjan Mukherjee is a Professor of Mechanical Engineering at Michigan State University (MSU). He received his B.Tech. degree from the Indian Institute of Technology, Kharagpur, in 1987 and his MS and PhD degrees from the University of California, Santa Barbara, in 1989 and 1991, respectively, all in Mechanical Engineering. Prior to joining MSU, he was an Assistant Professor in the Department of Mechanical Engineering at Naval Postgraduate School in Monterey, California, from 1991 to 1996. Ranjan Mukherjee is a Fellow of the ASME, a recipient of the 2008 Fulbright Research Scholar Award, and the 2011 MSU Withrow Distinguished Senior Scholar Award.


Refreshments will be served.