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Session 3: State of the art of engineered actuators approaching muscle behaviours

Joshua Schultz, University of Tulsa

Bio: Joshua Schultz received the B.S. degree from Tufts University, Medford, MA, USA, in 2002, the M.S. degree from Vanderbilt University, Nashville, TN, USA, in 2004, and the Ph.D. degree from the Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA, in 2012, all in mechanical engineering. From 2004 to 2008, he was a member of the Power Systems and Motion Control Group, Printing Services and Solutions Division, Lexmark International, Lexington, KY, USA. From 2012 to 2013, he was a Postdoctoral Fellow with the Department of Advanced Robotics, Istituto Italiano di Tecnologia, Genoa, Italy. Joshua Schultz is an assistant professor of Mechanical Engineering at College of Engineering & Natural Sciences, University of Tulsa. His research focuses primarily on soft robotics, in particular the role of small on-off cell-like units linked together by compliant material to generate motion as a whole. Because of the discretized, decentralized nature of these devices, this also involves control of quantized systems. He is also interested in properties of anthropomorphic hands and the role of compliance in grasping & manipulation. Dr. Schultz received the 2011 Achievement Rewards for College Scientists Foundation Scholarship.

Title: Muscles are more than just force sources: examining system dynamics of muscle-like actuators

Abstract: The ability of systems with muscle-like actuators to keep functioning after sustaining damage is a powerful motivation to develop such systems. In recent years, many unique and interesting platforms have been developed. However, the primary mode of operation of these systems has been to send each unit that makes up the “muscle” an identical control signal, just as one would a servomotor and then “hope for the best”. This method is at best, a missed opportunity, and at worst, could cause erratic or undesirable performance of the robot if units are damaged or the external environment is not as expected. Muscle-like actuators composed of discrete parts have a number of interesting properties that arise from their discrete structure. The control designer has authority not merely over the feedback control signal at each sampling interval, but also over the architecture of the ``muscle'' at design time, and which units to use to implement the control signal at runtime. This additional freedom can be used to produce desired behavior of the robot, recover from damage, or mitigate the challenges posed by the discrete architecture. This means that focused study on how the system dynamics of the actuator varies with architecture and choice of activation as it is controlled is warranted. This talk will give an overview of some of the key dynamic effects inherent in muscle-like actuators and propose helpful mathematical tools and notational devices that have been developed to describe and understand these behaviors.

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Koh Hosoda, Osaka University

Bio: Koh Hosoda received the Ph.D. degree in mechanical engineering from Kyoto University, Kyoto, Japan, in 1993. He was an Assistant Professor in the Department of Mechanical Engineering from 1993 to 1997, and an Associate Professor in the Graduate School of Engineering from 1997 to 2010, at Osaka University. He was a Guest Professor in the Artificial Intelligence Laboratory, University of Zurich, from April 1998 to March 1999. He was a group leader of JST Asada ERATO Project from 2005 to 2010. From 2010 to 2014, he was a Professor in the Graduate School of Information Science and Technology, Osaka University. Since 2014, he has been a Professor in the Graduate School of Engineering Science, Osaka University.

Title: Attempts to develop artificial muscles

Abstract: I would like to talk about our attempt to cultivate artificial “biological” muscle. In the presentation, I would like to introduce some of our attempt to realize artificial muscle out of biological cells. For realizing muscles out of cells, there are two main difficulties: how we can make a structure, and how we can excite them. I will show some of our attempt cultivating muscle cells into a structure by applying cyclic force

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Maziar A. Sharbafi & Tom Verstraten

Maziar Ahmad Sharbafi received the B.Sc. at Sharif University of Technology and M.Sc., and Ph.D. degrees at University of Tehran, all in control engineering. His current research interests include bio-inspired locomotion control based on conceptual and analytic approaches, postural stability, and the application of dynamical systems and nonlinear control to hybrid systems such as legged robots and exoskeletons. Currently, he is an assistant professor in Electrical and Computer Engineering Department of University of Tehran and a guest researcher at the Lauflabor Locomotion Laboratory, TU Darmstadt.

Tom Verstraten received his Master in Electromechanical Engineering from the Vrije Universiteit Brussel (VUB) in 2012. After working in industry for a year, he started a Ph.D. at the VUB, funded by a Ph.D. fellowship of the Research Foundation - Flanders (FWO). He received his doctoral degree in 2018. As a part of his Ph.D. project, he worked as a visiting researcher at TU Darmstadt (Germany) for a period of four months in 2017. His primary research focus is the study and development of energy-efficient actuators exploiting compliance and redundancy.

Title: Hybrid actuator and redundancy to mimic biological locomotor actuation behaviour and improve energy efficiency

Abstract: Muscles are arguably the best-known actuation technology that approaches a perfect force source i.e. one with extremely low impedance (perfectly backdrivable) and stiction, although with only moderate bandwidth. A better understanding of how actuator design supports locomotor function may help design and develop novel and more functional powered assistive or robotic legged systems. In this talk we present two different approaches to approach biological actuators, in both combinations of different actuators are utilized in a hybrid design.

In the first part of this talk, we focus on the axial leg function (e.g., spring-like hopping) based on a novel concept of a hybrid electric-pneumatic actuator (EPA). This enhanced variable impedance actuator (VIA) shares the advantages of EM and PAM combining precise control with compliant energy storage required for efficient, robust and versatile human-like leg motions via simple control laws. SEPA

In the second part of this talk, we discuss how the energy efficiency of actuators in demanding tasks can be enhanced by coupling multiple motors to a single joint. We explain the benefits of the kinematically redundant dual-motor actuator (DMA) and the statically redundant +SPEA concept, and demonstrate how they can generate energy-efficient human-like motion.

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