MAE Seminar: Distributed Compliance: From Monolithic Systems to Soft Robots

Abstract: While robots and engineering artifacts are becoming increasingly intelligent, innovations in their structural design and embodiments have not kept pace. Most robots still consist of myriad bulky, rigid parts connected by interfaces or joints leading to non-optimal performance. In contrast, around 90 percent of nature’s species (invertebrates) are designed seamlessly and use material elasticity to undergo spatial continuum deformation. In this talk, Krishnan will demonstrate this bioinspired design paradigm of distributed compliance in monolithic compliant mechanisms and soft robots. Design of spatial compliant mechanisms are hard because they constitute several interconnected flexible members oriented in three-dimensional space. He will present a novel method to functionally characterize the different compliant members by visualizing load flow in them. The resulting insights will be used in a conceptual topology design tool coupled with an immersive virtual reality-based framework. The resulting methodology can be used to design negative Poisson’s-ratio architectures and shape adaptive structures. Applying the paradigm of distributed compliance to soft mechanisms leads to a class of soft robotic actuators that combines fibers, pressurized fluids and stretchable elastomeric skins. Design and analysis of fiber-reinforced soft robots is complicated because of the coupling of the local microstructure with large global deformations. Krishnan will present a unique modeling technique to analyze their pressure-induced deformation behavior, and accompanying insights on how soft robots can be designed by inverse design and combining different fiber-reinforced building blocks. Finally, he will demonstrate the design and analysis method through two examples: an upper-extremity prosthesis and exoskeleton, and a soft continuum manipulator for berry harvesting.

Bio: Girish Krishnan is an assistant professor in industrial and enterprise systems engineering at University of Illinois at Urbana-Champaign. He earned a Ph.D. degree from University of Michigan in 2011 and a master's degree from Indian Institute of Science, Bangalore, in 2007. Krishnan is the recipient of the 2015 NSF Early Career Award (CAREER), the 2016 UIUC council award for excellence in advising and the 2017 Freudestein Young Investigator award (ASME), in addition to best paper awards and teaching excellence awards. He has published approximately 18 peer-reviewed journals and 30 conference proceedings, and holds two patents.