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Alireza Ramezani

Ph.D. ME, University of Michigan, Ann Arbor; Post-doc, AE, Cal-Tech; 1200 E California Blvd – Pasadena, CA 91125; aramez@caltech.edu

Research

Check me on google scholar.

Supervised Ph.D. students

Jonathan E. Hoff (EE, University of Illinois)

Syed A. Usman (EE, University of Illinois)

Research Statement


My works resides at the intersection of control theory and robotics, the intersection of theory and experiment. I possess a wide range of analytical skills that encompass control theory subjects, such as robust, adaptive, nonlinear \& linear, optimal and embedded control, to name a few. Additionally, I can combine my inspirations from nature with cutting-edge technological advancements to design state-of-the-art machines. In recent years, electronic devices that are anchored to small form factor (SFF) computing units and sensors have experienced considerable growth. They have high performance and are affordable. Part manufacturing technology reinvigorated by automation technology and new material science has diminished our manufacturing wait time to a few hours.

B2: photo courtesy of Soon-Jo Chung, University of Illinois

B2: Science Robotic (AAAS), photo courtesy of Alireza Ramezani, Seth Hutchinson & Soon-Jo Chung, University of Illinois.

Additive manufacturing machines (AMM) showcase novel prototyping approaches and seamlessly convert our computer-assisted designs to metal, plastic and reinforced polymer parts. I intend to leverage this opportunity to develop novel machines that help expand and understand the theory of nonlinear systems. In my work, I continuously attempt to exhibit these goals.

My research examines underactuated and highly dynamic robotic systems with non-trivial morphologies, which in general exhibit unstable modes and depend on fast-loop model-based controllers. An overactuated multi-rotor vehicle relied on its design redundancy to negotiate an optimal trajectory, a chiropteran-style or avian-inspired micro aerial vehicle (MAV) dancing in the air with great composure, a free-floating robotic arm reorienting itself in outer space subject to nonholonomic constraints, and a multi-link triphibian capable of negotiating land, sea and air exemplify the subjects of my interest. These challenging problems are rich in control theory and embody sophisticated nonlinear dynamics with affine-in-control or non-affine-in-control architecture. A flying robot with an inter-segmental body and compliant terminal organs subject to hard-to-model aeroelasticity is non-affine-in-control, whereas a walking bipedal robot that intermittently interacts with the environment is affine-in-control. I employ advanced theories of nonlinear control to design model-based and nonlinear solutions for these systems.

The pursuit of model-based design paradigms for MAVs is prohibitively restricted because these controllers are sophisticated and hard-to-embed; ad hoc methods are used as the traditional design tool instead. In my research, I aim to address these restrictions by drawing inspiration from the animal kingdom and incorporating emerging technologies such as approximation computing and thin film transistor (TFT) technology into my designs to set the ground for on-board, distributed computation and sensing.

Robot Gallery

Bellow you will see the robots that I have worked on.


B2 close-up view; B2’s morphology is adaptive and can change using the on-board computing unit and power electronics. My goal is to use tools from nonlinear control theory and this machine to study bat flight.

B2's articulated body.

B2 is the bat-inspired robot I designed at University of Illinois in collaboration with Soon-Jo Chung (Cal-tech) and Seth Hutchinson (UIUC), image courtesy Alireza Ramezani.

Allice, this is a UAV I designed to study sharp pitch maneuvers. If you want to know more about it please see my ICRA 2016 paper. Image courtesy of Alireza Ramezani.

Allice, this is a UAV I designed to study sharp pitch maneuvers. If you want to know more about it please see my ICRA 2016 paper. Image courtesy of Alireza Ramezani.

DFA: photo courtesy of Raffaelo D'Andrea, ETH Zurich.

This is distributed flight array (DFA). I was involved in developing the hardware and distributed flight controller for this robot back in 2009. This multirotor platform consists of autonomous rotor modules that are able to drive, dock with their peers, and fly in a coordinated fashion. These modules are organized as distributed computational units with minimal sensory input. Photo courtesy of Raffaelo D’Andrea, ETH Zurich.

ATRIAS: photo courtesy of Jessy Grizzle, University of Michigan.

ATRIAS: designed by Jonathan Hurst at Oregon State University. I was involved in designing nonlinear controller for this platform during my Ph.D. work at the Unviersity of Michigan. Photo courtesy of Jessy Grizzle, University of Michigan.

Media Coverage

My post-doc research with Seth Hutchinson (UIUC) and Soon-Jo Chung (Cal-Tech) has become the cover article for Science Robotic magazine. For full news coverage of my article please visit Science magazine website,

B2 hit the cover article of Science Robotic (AAAS).

B2 hit the cover article of Science Robotic (AAAS).

“A robot that flies like a bat”,  published online in Nature,

“Bat Robot Offers Safety and Maneuverability in Bio-inspired Design”, published online in IEEE Spectrum,

“Bat Bot Soon to Take to the Skies”, published online in The Wall Street Journal,

“Illinois robotic innovation spreads its wings: BTN LiveBIG”, published online in Big Ten Network,

“Wow! There Is a New Bat Drone”, published online in Associated Press,

“Behold Bat Bot, the First Flying Robot Bat”, published online in Popular Mechanics,

“Bat Bot is an autonomous drone that mimics a bat’s flight”, published online in engadget

“Just Look At This Robot Bat Go”, published online in Gizmodo,

“The flying Bat Bot can swoop and dive like the real thing”, published online in The Verge

” FINALLY, THE ROBOT BAT WE DESERVE AND THE ROBOT BAT WE NEED”, published online in wired,

“Could this robot bat one day edge out quadrotors as the drone of the future?”, published online in ZDNet,

“BAT ROBOTS COULD BE FLYING AROUND DISASTER ZONES WITHIN FIVE YEARS”, published online in EuroNews,

“Bat Bot rises: Engineers create winged robotic drone that flies like a bat”, published online in Yahoo News,

“This new drone design is inspired by bats’ flight”, published online in CBS News,

“Bat-Bot is a Drone That Flies Like a Bat”, published online in NBC News

“A ‘Bat Bot’ takes flight”, published online in PBS News,

“Bat-inspired robot swoops and dives like the real thing”, published online in New Scientist

“Advanced robotic bat’s flight characteristics simulates the real thing”, published online in EurekAlert,

“Bat Bot is the biomimetic flying soft robot we deserve”, published online in Techcrunch,

“Meet the ‘Bat Bot’: Scientists unveil robot that flies just like a bat”, published online in Fox News

“Bat Bot Flying Robot Mimics ‘Ridiculously Stupid’ Complexity Of Bat Flight”, published online in npr,

“Bat robot takes wing”, published online in ScienceNews “The Bot That Flies Like a Bat”, published online in Air&Space,

“Advanced robotic bat’s flight characteristics simulates the real thing”, published online in phys.org,

“Robot bat technology flies circles around other drones”, published online in the Columbian,

Current Research


My post-doctoral works span bio-inspired and space robotics and are anchored to theory and experiment to address the modeling, feedback design, and system design of: 1) chiropteran-style flying robots, and 2) triphibian outer space explorers. In a natural setting, agile aerial locomotion is the defining characteristic of bats. Chiropterans arguably showcase the most sophisticated morphology among flying mammals; they have several types of joints that interlock bones and muscles to one another to create a metamorphic musculoskeletal system with over 40 degrees of freedom (DoF). Current methods of studying bat flight are limited to conventional off-board motion capture systems, which cannot explain the numerous flight control strategies that bats employ. I aim to combine state-of-the-art machine design and cutting-edge micro-electro-mechanical systems (MEMS) to add to efforts in studying bats’ array of physiological and flight specializations. My recent collaboration with Seth Hutchinson, University of Illinois, and Soon-Jo Chung , California Institute of Technology, led to Bat Bot (B2), which has revealed exciting results.

B2 is a fully self-contained, autonomous flying robot weighing 93 grams that was created to mimic the morphological properties of bat wings. Instead of using a large number of distributed control actuators, I devised highly stretchable silicone-based membrane wings that are controlled at a reduced number of dominant wing joints to best match the morphological characteristics of bat flight. I paired my bio-mimetic design with recent biological studies (Kenny Breuer and Sharon Swartz at Brown University) to identify the dominant DoFs in the bat flight mechanism and incorporated them in B2’s design by means of a series of mechanical constraints adaptively morphed by closed-loop feedback. These biologically meaningful DoFs include asynchronous and mediolateral movements of the armwings and dorsoventral movements of the legs. The continuous surface and elastic properties of bat skin under wing morphing are realized by an ultrathin (56 micrometers) membranous skin that covers the skeleton of the morphing wings. I paired B2’s internal dynamics (an invariant manifold restricted to initial states) and phase-plane analysis tools to develop the unique morphological specializations of B2 and carefully delineate the role of compliant terminal organs (e.g., forelimbs and hindlimbs) in chiropteran-style flight.

Source: Youtube

Courtesy of Verge

Ph. D. Work


ATRIAS: photo courtesy of Jessy Grizzle, University of Michigan.

ATRIAS: photo courtesy of Jessy Grizzle, University of Michigan.

My Ph.D. research contributed to the nonlinear feedback design of bipedal robots with compliant components by leveraging a design framework based on the method of hybrid zero dynamics (HZD) to pair the energetic efficiency of locomotion and underactuation. I developed controllers for walking robots on level ground with energy efficiency as the performance objective and embedded my designs to a robot called Assume The Robot Is A Sphere (ATRIAS) to delineate the interplay between stability, efficiency, and passivity. ATRIAS is designed for the study of 3D bipedal locomotion, with the aim of combining energy efficiency, speed, and robustness with respect to natural terrain variations in a single platform.

ATRIAS is highly underactuated and its sagittal plane dynamics are designed to embody the spring loaded inverted pendulum (SLIP), which has been shown to provide a dynamic model of the body center of mass during steady running gaits of a wide array of terrestrial animals. By consolidating an HZD-based gait generator and a detailed hybrid nonlinear dynamic model and leveraging them to optimize parametric walking gaits with respect to the cost of mechanical transport, a dimensionless measure of energetic efficiency, I demonstrated asymptotically stable walking gaits, despite the high degree of underactuation of the robot.

Source: Youtube

Source: Youtube

Prior Works


My research during a micro-robotic competition at the Institute of Robotics and Intelligent Systems (IRIS), Swiss Federal Institute of Technology (ETH Zurich), involved the fabrication and control design of wireless-resonant magnetic propelled micro robotic agents called  MagMite. At the Institute for Dynamic Systems and Control (IDSC), ETH Zurich, I was involved in the Distributed Flight Array (DFA) project. This platform is a state-of-the-art multi-agent flying robot and consists of modules each of which is self-contained and autonomous.

DFA: photo courtesy of Raffaelo D'Andrea, ETH Zurich.

DFA: photo courtesy of Raffaelo D’Andrea, ETH Zurich.

Each module embodies a set of omnidirectional drives that enables it to drive on the ground and has a fixed-pitch propeller that can generate enough thrust to lift itself into the air but is unstable in flight. Not until these modules are joined do these relatively simple devices evolve into a sophisticated multi-rotor system capable of coordinated flight. My contributions to the DFA project were two-fold: 1) nonlinear multi-body modeling and decentralized flight control design and 2) embedded system design.

Courtesy of Rafaello D’Andrea

Interests


My long-term research goal is to develop the systems science and associated feedback controllers that will create the next generation of robots that will be hyper-dynamic, possessing performance attributes such as high speed, ultra-efficiency, super-maneuverability and extreme agility. My immediate goals in the next five years are to focus on research thrusts on bio-inspired and space robotics. I intend to expand locomotion science with impetuses from biology to achieve triphibian solutions that can negotiate demanding environments (e.g., uneven natural terrains, cluttered environments). Below I describe the proposed projects that share the common theme of hard-to-model operating regimes:

Chiropteran-Style MAVs:
My post-doctoral research, which was supported by a National Robotics Initiative (NRI) grant, and Ph.D. work set the ground for strong relationships with collaborators across the nation including PIs from University of Michigan, University of Illinois, Caltech, Carnegie Mellon University and Brown University. I endeavor to leverage this strong network to mimic chiropteran-style flight, which is arguably the most challenging locomotion in nature, in the context of robotic inspired biology. This encompasses solving challenging control allocation problems, ultramodern flight mechanisms, and cutting-edge embedded system designs.

Robot Satellites:
Current space technology limits tasks such as the repair, servicing, and construction of spacecraft and space stations in orbit to astronaut extra vehicular activity (EVA). Eliminating the need for EVA through the use of space robotics and teleoperated manipulators would greatly reduce both hazards to astronauts and mission costs. My strong background in closed-loop feedback design for free-flying kinematic chains subject to holonomic and nonholonomic constraints is the major impetus to pursue this track.

Articles


1: A. Ramezani, S.-J. Chung, and S. Hutchinson, ”Roll conjugate momentum regulation in articulated flapping flight,” IEEE Trans. on Robotics, submitted.

2: J. E. Hoff, A. Ramezani, S.-J. Chung, and S. Hutchinson, ”Synergistic design of a bio-inspired micro aerial vehicle with articulated wings,” invited for the International Journal on Robotics Research special issue, submitted.

3: A. Ramezani, S.-J. Chung, and S. Hutchinson, ”A biomimetic robotic platform to study flight specializations of bats,” Science (Robotics-AAAS), volume 2, issue 3, pages: eaal2505, February 2017 (cover article; [also featured in Nature 542,140 (09 February 2017) doi:10.1038/542140a]).

4: A. Ramezani, J. Hurst, K. A. Hamed and J. W. Grizzle, ”Performance analysis and feedback control of atrias, a 3D bipedal robot,” ASME Journal of Dynamic Systems Measurement and Control, volume 136, issue 2, start page: 21012, March 2014.

5: H.-W. Park, A. Ramezani, and J. W. Grizzle, ”A finite-state machine for accommodating unexpected large ground height variations in bipedal robot walking,” IEEE Trans. on Robotics, volume 29, issue 2, pp. 331-345, April 2013.

Proceedings of Technical Meetings


1: A. Ramezani, S.-J. Chung, and S. Hutchinson, ”Sharp banked turn of a nonholonomically constrained flapping system,” 2018 American Control Conference (ACC), submitted.

2: A. Ramezani, S. U. Ahmed, J. E. Hoff, S.-J. Chung, S. Hutchinson, ”Describing aerial locomotion of an articulated MAV with stable periodic orbits,” in M. Cutkosky, P. Verschure, T. Prescott, M. Mangan, M. Desmulliez, A. Mura, Eds., Biomimetic and Biohybrid Systems: The 6th Int’l. Conf. on Biomimetic and Biohybrid Systems, Lecture Notes in Artificial Intelligence, Springer-Verlag, Stanford University, Stanford, CA, July 25-28, 2017, pp. 394-405.

3: J. E. Hoff, A. Ramezani, S.-J. Chung, and S. Hutchinson, ”Reducing versatile bat wing conformations to a 1-DoF machine,” in M. Cutkosky, P. Verschure, T. Prescott, M. Mangan, M. Desmulliez, A. Mura, Eds., Biomimetic and Biohybrid Systems: The 6th Int’l. Conf. on Biomimetic and Biohybrid Systems, Lecture Notes in Artificial Intelligence, Springer-Verlag, Stanford University, Stanford, CA, July 25-28, 2017, pp. 181-192.

4: S. U. Ahmed, A. Ramezani, S.-J. Chung, and S. Hutchinson, ”From Rousettus aegyptiacus landing to robotic landing: regulation of CG-CP distance using a nonlinear closed-loop feedback,” Proc. IEEE International Conference on Robotics and Automation (ICRA), Marina Bay Sands, Singapore, May 29 to June 3, 2017, pp. 3560-3567.

5: J. E. Hoff, A. Ramezani, S.-J. Chung, and S. Hutchinson, ”Synergistic design of a bio-inspired micro aerial vehicle with articulated wings,” Robotics Science and Systems Conference (RSS), University of Michigan, Ann Arbor, MI, June 20-22, 2016.

6: A. Ramezani, X. Shi, S.-J. Chung, S. Hutchinson, ”Bat Bot (B2), a biologically inspired flying machine,” Proc. IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweeden, May 16-21, 2016, pp. 3219-3226.

7: A. Ramezani, X. Shi, S.-J. Chung, and S. Hutchinson, ”Lagrangian modeling and flight control of articulated-winged bat robot,” Proc. IEEE/RSJ Int’l. Conf. on Intelligent Robots and Systems (IROS), Hamburg, Germany, September 28 to October 2, 2015, pp. 2867-2874.

8: A. Ramezani, X. Shi, S.-J. Chung, and S. Hutchinson, ”Nonlinear flight controller synthesis of a bat-inspired micro aerial vehicle,” Proc. AIAA Guidance, Navigation, and Control Conference, San Diego, CA, January 4-8, 2016, AIAA 2016-1376.

9: B. G. Buss, A. Ramezani, K. A. Hamed, B. A. Griffin, K. S. Galloway, J. W. Grizzle, ”Preliminary walking experiments with underactuated 3D bipedal robot MARLO,” Proc. IEEE/RSJ Int’l. Conf. on Intelligent Robots and Systems (IROS), Chicago, IL, September 14-18, 2014, pp. 2529-2536.

10: J. W. Grizzle, A. Ramezani, B. Buss, B. Griffin, K. A. Hamed, and K. S. Galloway, ”Progress on controlling MARLO, an ATRIAS-series 3D underactuated bipedal robot,” Dynamic Walking Conference, Robotic Institute at Carnegie Mellon University, Pittsburgh, PA, June 10-13, 2013.

11: A. Ramezani, J.W. Grizzle, ”A feedback control of ATRIAS, a 3D bipedal robot,” 15th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines (CLAWAR), volume 23, pages: 26, Johns Hopkins University, Baltimore, MD, July 23-26, 2012.

12: H.-W. Park, K. Sreenath, A. Ramezani, and J. W. Grizzle, ”Switching control design for accommodating large step-down disturbances in bipedal robot walking,” International Conference on Robotics and Automation (ICRA), St. Paul, MN, May 14-18, 2012, pp. 45-50.

13: R. Oung, A. Ramezani, R. D’Andrea, ”Feasibility of a distributed flight array,” Proc. 48th IEEE Conference on Decision and Control (CDC), Shanghai, China, December 16-18, 2009, pp. 3038-3044.

14: A. Ramezani, S. Hosseini-Hashemi, ”The effects of step, ramp and sinusoidal forces on response of multistep Timoshenko beam,” 2nd International Operational Modal Analysis Conference (IOMAC), Copenhagen, Denmark, April 30 to May 2, 2007, pp. 593-601.