GRASP Special Seminar - Koushil Sreenath, University of Michigan, "Achieving Walking and Running on a Biped with Compliance: A Feedback Control Design"

Abstract: MABEL is a planar bipedal test bed with no feet, weighs around 65 Kg, is 1 m tall at the hips, and has a novel transmission with a series compliant element to enhance energy efficiency and agility of dynamic locomotion. The presence of compliance in MABEL’s transmission has led to new control challenges: Compliance increases the degree of underactuation, and also raises the question of how to use the compliance effectively.

This talk will illustrate a controller design based on the Hybrid Zero Dynamics (HZD) that preserves the natural compliant dynamics of the system to achieve provably stable, efficient, fast and robust bipedal walking resulting in a walking gait with mechanical cost of transport that is just a factor of two away from that of humans, and in a walking world speed record of 1.5 m/s.

Further, biomechanics studies have shown that humans and animals adjust their leg stiffness to accommodate for variations in terrain and ground stiffness during running using a combination of tendons, and muscles. Motivated by this, a novel control design that embeds an active force control in the form of virtual compliance within the compliant HZD framework will be presented to achieve running gaits on MABEL.

Presenter's biography

Koushil Sreenath is a Ph.D. candidate in the Electrical Engineering and Computer Science Department at The University of Michigan, Ann Arbor. His research interests are in modeling, feedback design, and experiments in legged robotics, as well as adaptive sampling and resource allocation in mobile wireless sensor networks. His work on the bipedal robot MABEL was featured on The Discovery Channel, and his work on adaptive sampling with mobile sensor networks resulted in a book. He received the M.S. in Mathematics from Univ. of Michigan at Ann Arbor in 2011, he was a Research Engineer with the Intelligent Controls Group, Saint-Gobain R&D in 2006-2007, he received the M.S. in Electrical Engineering from Univ. of Texas at Arlington in 2005, and the B.E. from PES Inst. of Tech., Bangalore, in 2002.