News & Events

1,414 News items, Awards, Events and Talks related to MERL and its staff.



Learn about the MERL Seminar Series.



  •  NEWS    MERL launches Postdoctoral Research Fellow program
    Date: September 21, 2022
    MERL Contacts: Philip V. Orlik; Anthony Vetro
    Research Areas: Applied Physics, Artificial Intelligence, Communications, Computational Sensing, Computer Vision, Control, Data Analytics, Dynamical Systems, Electric Systems, Electronic and Photonic Devices, Machine Learning, Multi-Physical Modeling, Optimization, Robotics, Signal Processing, Speech & Audio
    Brief
    • Mitsubishi Electric Research Laboratories (MERL) invites qualified postdoctoral candidates to apply for the position of Postdoctoral Research Fellow. This position provides early career scientists the opportunity to work at a unique, academically-oriented industrial research laboratory. Successful candidates will be expected to define and pursue their own original research agenda, explore connections to established laboratory initiatives, and publish high impact articles in leading venues. Please refer to our web page for further details.
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  •  NEWS    Yebin Wang appointed as an Associate Editor for ICRA 2023.
    Date: September 15, 2022
    MERL Contact: Yebin Wang
    Research Areas: Control, Dynamical Systems, Robotics
    Brief
    • Yebin Wang, a Senior Principal Research Scientist in MERL's Electric Machines and Devices, is serving as an Associate Editor for the IEEE International Conference on Robotics and Automation (ICRA) 2023.


      As the flagship conference of the IEEE Robotics and Automation Society, ICRA will bring together the world's top researchers and most important companies to share ideas and advances in our field.
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  •  NEWS    Anantaram Varatharajan named one of the star reviewers for 2021 by the Editorial Board of the IEEE Transactions on Energy Conversion
    Date: September 6, 2022
    Where: IEEE Transactions on Energy Conversion
    MERL Contact: Anantaram Varatharajan
    Research Area: Electric Systems
    Brief
    • The Star Reviewers are recognized by the Editorial Board as the individuals who have consistently provided rigorous quality reviews in a timely fashion and on multiple occasions within a given year.
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  •  TALK    [MERL Seminar Series 2022] Prof. Chuang Gan presents talk titled Learning to Perceive Physical Scenes from Multi-Sensory Data
    Date & Time: Tuesday, September 6, 2022; 12:00 PM EDT
    Speaker: Chuang Gan, UMass Amherst & MIT-IBM Watson AI Lab
    MERL Host: Jonathan Le Roux
    Research Areas: Artificial Intelligence, Computer Vision, Machine Learning, Speech & Audio
    Abstract
    • Human sensory perception of the physical world is rich and multimodal and can flexibly integrate input from all five sensory modalities -- vision, touch, smell, hearing, and taste. However, in AI, attention has primarily focused on visual perception. In this talk, I will introduce my efforts in connecting vision with sound, which will allow machine perception systems to see objects and infer physics from multi-sensory data. In the first part of my talk, I will introduce a. self-supervised approach that could learn to parse images and separate the sound sources by watching and listening to unlabeled videos without requiring additional manual supervision. In the second part of my talk, I will show we may further infer the underlying causal structure in 3D environments through visual and auditory observations. This enables agents to seek the sound source of repeating environmental sound (e.g., alarm) or identify what object has fallen, and where, from an intermittent impact sound.
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  •  AWARD    Marcus Greiff receives Outstanding Student Paper Award at CCTA 2022
    Date: August 25, 2022
    Awarded to: Marcus Greiff
    MERL Contact: Marcus Greiff
    Research Areas: Control, Dynamical Systems, Robotics
    Brief
    • Marcus Greiff, a Visiting Research Scientist at MERL, was awarded one of three outstanding student paper awards at the IEEE CCTA 2022 conference for his paper titled "Quadrotor Control on SU(2)xR3 with SLAM Integration". The award was given for originality, clarity, and potential impact on practical applications of control. The work presents a complete UAV control system design, facilitating autonomous supermarket inventorying without the need for external motion capture systems. A video of the experiments is on YouTube, including both simulations and real-time examples.
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  •  NEWS    MERL congratulates Prof. Alex Waibel on receiving 2023 IEEE James L. Flanagan Speech and Audio Processing Award
    Date: August 22, 2022
    MERL Contacts: Chiori Hori; Jonathan Le Roux; Anthony Vetro
    Research Areas: Artificial Intelligence, Machine Learning, Speech & Audio
    Brief
    • IEEE has announced that the recipient of the 2023 IEEE James L. Flanagan Speech and Audio Processing Award will be Prof. Alex Waibel (CMU/Karlsruhe Institute of Technology), “For pioneering contributions to spoken language translation and supporting technologies.” Mitsubishi Electric Research Laboratories (MERL), which has become the new sponsor of this prestigious award in 2022, extends our warmest congratulations to Prof. Waibel.

      MERL Senior Principal Research Scientist Dr. Chiori Hori, who worked with Dr. Waibel at Carnegie Mellon University and collaborated with him as part of national projects on speech summarization and translation, comments on his invaluable contributions to the field: “He has contributed not only to the invention of groundbreaking technology in speech and spoken language processing but also to the promotion of an abundance of research projects through international research consortiums by linking American, European, and Asian research communities. Many of his former laboratory members and collaborators are now leading R&D in the AI field.”

      The IEEE Board of Directors established the IEEE James L. Flanagan Speech and Audio Processing Award in 2002 for outstanding contributions to the advancement of speech and/or audio signal processing. This award has recognized the contributions of some of the most renowned pioneers and leaders in their respective fields. MERL is proud to support the recognition of outstanding contributions to the field of speech and audio processing through its sponsorship of this award.
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  •  AWARD    ACM/IEEE Design Automation Conference 2022 Best Paper Award nominee
    Date: July 14, 2022
    Awarded to: Weidong Cao, Mouhacine Benosman, Xuan Zhang, and Rui Ma
    MERL Contact: Mouhacine Benosman
    Research Area: Artificial Intelligence
    Brief
    • The Conference committee of the 59th Design Automation Conference has chosen MERL's paper entitled 'Domain Knowledge-Infused Deep Learning for Automated Analog/RF Circuit Parameter Optimization', as a DAC Best Paper Award nominee. The committee evaluated both manuscript and submitted presentation recording, and has chosen MERL's paper as one of six nominees for this prestigious award. Decisions were based on the submissions’ innovation, impact and exposition.
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  •  AWARD    International Conference on Artificial Intelligence Circuits and Systems (AICAS) 2022 Openedges Award
    Date: June 15, 2022
    Awarded to: Yuxiang Sun, Mouhacine Benosman, Rui Ma.
    MERL Contact: Mouhacine Benosman
    Research Area: Artificial Intelligence
    Brief
    • The committee of the International Conference on Artificial Intelligence Circuits and Systems (AICAS) 2022, has selected MERL's paper entitled 'GaN Distributed RF Power Amplifier Automation Design with Deep Reinforcement Learning' as a winner of the AICAS 2022 Openedges Award.

      In this paper MERL researchers propose a novel design automation methodology based on deep reinforcement learning (RL), for wide-band non-uniform distributed RF power amplifiers, known for their high dimensional design challenges.
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  •  EVENT    Sonja Glavaski-Radovanovic presents at MERL's Annual Women In Science Event
    Date: Monday, August 8, 2022
    Location: MERL
    MERL Contact: Elizabeth Phillips
    Brief
    • On August 8th MERL hosted its annual Women in Science event-in person. Our guest speaker Sonja Galvaski-Radovanovic, Chief Energy Digitalization Scientist and Principal Technology Strategy advisor for the Energy & Environment Directorate at PNNL, shared career wisdom and led a lively, interactive discussion with MERL staff and interns about the significant contributions women have made to the scientific society.
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  •  AWARD    MERL receives 33rd ARIB Radio Achievement Award
    Date: June 28, 2022
    Awarded to: Yukimasa Nagai, Jianlin Guo, Shoichi Kitazawa, Kazuto Yano.
    MERL Contacts: Jianlin Guo; Philip V. Orlik
    Research Areas: Communications, Electric Systems
    Brief
    • Mitsubishi Electric Corporation (Yukimasa Nagai), MERL (Jianlin Guo), Muroran Institute of Technology (Shoichi Kitazawa) and Advanced Telecommunications Research Institute International (Kazuto Yano) jointly won the 33rd ARIB Radio Achievement Award with "IEEE 802.19.3 Standardization and Development for Sub-1 GHz Wireless Frequency Coexistence". The ARIB is an organization similar to the FCC in the U.S. It is responsible for setting standards for all radio communications in Japan at the request of the Ministry of Internal Affairs and Communications (MIC). In order to promote the effective use of radio waves, the "Radio Achievement Award" is given annually to an individual or organization that has made a special achievement in the effective use of radio waves. This award is the most prestigious award in the field of wireless communications in Japan.
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  •  EVENT    MERL Celebrates 30th Anniversary
    Date: Wednesday, June 15, 2022
    Location: Cambridge, MA
    MERL Contacts: Philip V. Orlik; Elizabeth Phillips; Anthony Vetro; Richard C. (Dick) Waters
    Brief
    • On June 15th MERL celebrated 30 years of inspiration, imagination and innovation in Cambridge Massachusetts. We invite you to visit our website to learn more about our history, read a booklet describing our achievements during the last three decades, and watch a brief video highlighting some of the impacts we have had.
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  •  NEWS    MERL researchers win ASME Energy Systems Technical Committee Best Paper Award at 2022 American Control Conference
    Date: June 8, 2022
    Where: 2022 American Control Conference
    MERL Contacts: Ankush Chakrabarty; Christopher R. Laughman
    Research Areas: Control, Machine Learning, Multi-Physical Modeling, Optimization
    Brief
    • Researchers from EPFL (Wenjie Xu, Colin Jones) and EMPA (Bratislav Svetozarevic), in collaboration with MERL researchers Ankush Chakrabarty and Chris Laughman, recently won the ASME Energy Systems Technical Committee Best Paper Award at the 2022 American Control Conference for their work on "VABO: Violation-Aware Bayesian Optimization for Closed-Loop Performance Optimization with Unmodeled Constraints" out of 19 nominations and 3 finalists. The paper describes a data-driven framework for optimizing the performance of constrained control systems by systematically re-evaluating how cautiously/aggressively one should explore the search space to avoid sustained, large-magnitude constraint violations while tolerating small violations, and demonstrates these methods on a physics-based model of a vapor compression cycle.
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  •  NEWS    MERL researchers presented 9 papers at the American Control Conference (ACC)
    Date: June 8, 2022 - June 10, 2022
    Where: Atlanta, GA
    MERL Contacts: Karl Berntorp; Scott A. Bortoff; Ankush Chakrabarty; Stefano Di Cairano; Christopher R. Laughman; Marcel Menner; Rien Quirynen; Abraham P. Vinod; Avishai Weiss
    Research Areas: Control, Machine Learning, Optimization
    Brief
    • At the American Control Conference in Atlanta, GA, MERL presented 9 papers on subjects including autonomous-vehicle decision making and motion planning, realtime Bayesian inference and learning, reference governors for hybrid systems, Bayesian optimization, and nonlinear control.
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  •  NEWS    MERL work on 3D Printing in Orbit featured in IEEE Spectrum
    Date: June 3, 2022
    Where: IEEE Spectrum
    MERL Contacts: Avishai Weiss; William S. Yerazunis
    Research Areas: Applied Physics, Communications, Robotics
    Brief
    • MERL's research on on-orbit manufacturing was recently featured in an IEEE Spectrum article. The article, titled How Satellites Will 3D Print Their Own Antennas in Space gives an overview of MERL's efforts towards developing a system that construct spacecraft parts in their natural environment-- that is, in space. The technology, called OOM for On-Orbit Manufacturing, provides a way to manufacture not just antenna dishes, but general freeform sturctures on orbit and in a vacuum, using an solar-hardened resin based approach. This technology includes both a special high performance liquid resin, as well as a 3D freeform printer capable of building objects far larger than the as-launched satellite.

      An important aspect of the special resin is that all components have extremely low vapor pressures and do not boil away even in a vacuum. When exposed to solar ultraviolet, the resin hardens by polymerization crosslinking, forming a tough, rigid solid in a few seconds of exposure. No separate UV source is needed, making the entire process very energy efficient. Additionally, the crosslinking resin is heat resistant, and is unaffected to at least 400 degrees C. The 3D printer needed to print the resin is unlike common liquid-resin SLA printers- there is no vat of liquid resin, instead a shielded nozzle delivers the liquid resin directly to where the resin is needed. The result is the ability to construct large and very large structures, not just parabolic dishes, but also solar panel supports and structural trusswork, while in orbit. The system could even construct parts that were unanticipated during mission design and launch.

      MERL's On-Orbit Manufacturing Technology had previously been featured in a Mitsubishi Electric Corporation Press Release and was recently on display at a recent press exhibition in Tokyo, Japan.

      IEEE Spectrum is the flagship magazine and website of the IEEE, the world’s largest professional organization devoted to engineering and the applied sciences. IEEE Spectrum has a circulation of over 400,000 engineers worldwide, making it one of the leading science and engineering magazines.
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  •  NEWS    MERL researchers presented 5 papers and an invited workshop talk at ICRA 2022
    Date: May 23, 2022 - May 27, 2022
    Where: International Conference on Robotics and Automation (ICRA)
    MERL Contacts: Ankush Chakrabarty; Stefano Di Cairano; Siddarth Jain; Devesh K. Jha; Pedro Miraldo; Daniel N. Nikovski; Rien Quirynen; Arvind Raghunathan; Diego Romeres; Abraham P. Vinod; Yebin Wang
    Research Areas: Artificial Intelligence, Machine Learning, Robotics
    Brief
    • MERL researchers presented 5 papers at the IEEE International Conference on Robotics and Automation (ICRA) that was held in Philadelphia from May 23-27, 2022. The papers covered a broad range of topics from manipulation, tactile sensing, planning and multi-agent control. The invited talk was presented in the "Workshop on Collaborative Robots and Work of the Future" which covered some of the work done by MERL researchers on collaborative robotic assembly. The workshop was co-organized by MERL, Mitsubishi Electric Automation's North America Development Center (NADC), and MIT.
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  •  NEWS    MERL presenting 8 papers at ICASSP 2022
    Date: May 22, 2022 - May 27, 2022
    Where: Singapore
    MERL Contacts: Anoop Cherian; Chiori Hori; Toshiaki Koike-Akino; Jonathan Le Roux; Tim K. Marks; Philip V. Orlik; Kuan-Chuan Peng; Pu (Perry) Wang; Gordon Wichern
    Research Areas: Artificial Intelligence, Computer Vision, Signal Processing, Speech & Audio
    Brief
    • MERL researchers are presenting 8 papers at the IEEE International Conference on Acoustics, Speech & Signal Processing (ICASSP), which is being held in Singapore from May 22-27, 2022. A week of virtual presentations also took place earlier this month.

      Topics to be presented include recent advances in speech recognition, audio processing, scene understanding, computational sensing, and classification.

      ICASSP is the flagship conference of the IEEE Signal Processing Society, and the world's largest and most comprehensive technical conference focused on the research advances and latest technological development in signal and information processing. The event attracts more than 2000 participants each year.
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  •  NEWS    MERL Scientists Presenting 5 Papers at IEEE International Conference on Communications (ICC) 2022
    Date: May 16, 2022 - May 20, 2022
    Where: Seoul, Korea
    MERL Contacts: Jianlin Guo; Kyeong Jin (K.J.) Kim; Toshiaki Koike-Akino; Philip V. Orlik; Kieran Parsons; Pu (Perry) Wang; Ye Wang
    Research Areas: Artificial Intelligence, Communications, Computational Sensing, Computer Vision, Machine Learning, Signal Processing
    Brief
    • MERL Connectivity & Information Processing Team scientists remotely presented 5 papers at the IEEE International Conference on Communications (ICC) 2022, held in Seoul Korea on May 16-20, 2022. Topics presented include recent advancements in communications technologies, deep learning methods, and quantum machine learning (QML). Presentation videos are also found on our YouTube channel. In addition, K. J. Kim organized "Industrial Private 5G-and-beyond Wireless Networks Workshop" at the conference.

      IEEE ICC is one of two IEEE Communications Society’s flagship conferences (ICC and Globecom). Each year, close to 2,000 attendees from over 70 countries attend IEEE ICC to take advantage of a program which consists of exciting keynote session, robust technical paper sessions, innovative tutorials and workshops, and engaging industry sessions. This 5-day event is known for bringing together audiences from both industry and academia to learn about the latest research and innovations in communications and networking technology, share ideas and best practices, and collaborate on future projects.
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  •  NEWS    MERL's On-Orbit 3D Printing Technology Featured in Mitsubishi Electric Corporation Press Release
    Date: May 17, 2022
    Where: Tokyo, Japan
    MERL Contacts: Avishai Weiss; William S. Yerazunis
    Research Areas: Applied Physics, Communications
    Brief
    • Mitsubishi Electric Corporation announced that the company has developed an on-orbit additive-manufacturing technology that uses photosensitive resin and solar ultraviolet light for the freeform printing of satellite antennas in the vacuum of outer space.

      The novel technology makes use of a newly developed liquid resin that was custom formulated for stability in vacuum. The resin enables structures to be fabricated in space using a low-power process that utilizes the sun’s ultraviolet rays for photopolymerization. The technology specifically addresses the challenge of equipping small, inexpensive spacecraft buses with large structures, such as high-gain antenna reflectors, and enables on-orbit fabrication of structures that greatly exceed the dimensions of launch vehicle fairings. Resin-based on-orbit manufacturing is expected to enable spacecraft structures to be made thinner and lighter than conventional designs, which must survive the stresses of launch and orbital insertion, thereby reducing both total satellite weight and launch costs.

      Mitsubishi Electric’s resin-based on-orbit manufacturing enables small satellites to have large satellite capability, which reduces launch costs and allows for satellite technology to be used more than ever in applications such as communication and Earth observation. The technology is based on recent research by MERL's Control for Autonomy and Data Analytics groups.









      Links:

      Mitsubishi Electric Corporation Press Release
      SatMagazine: UV In The Sky With Resin: A novel, on-orbit manufacturing technique
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  •  NEWS    Arvind Raghunathan's publication is Featured Article in the current issue of the INFORMS Journal on Computing
    Date: April 1, 2022
    Where: INFORMS Journal on Computing (https://pubsonline.informs.org/journal/ijoc)
    MERL Contact: Arvind Raghunathan
    Research Areas: Artificial Intelligence, Machine Learning, Optimization
    Brief
    • Arvind Raghunathan co-authored a publication titled "JANOS: An Integrated Predictive and Prescriptive Modeling Framework" which has been chosen as a Featured Article in the current issue of the INFORMS Journal on Computing. The article was co-authored with Prof. David Bergman, a collaborator of MERL and Teng Huang, a former MERL intern, among others.

      The paper describes a new software tool, JANOS, that integrates predictive modeling and discrete optimization to assist decision making. Specifically, the proposed solver takes as input user-specified pretrained predictive models and formulates optimization models directly over those predictive models by embedding them within an optimization model through linear transformations.
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  •  NEWS    Toshiaki Koike-Akino gave an invited lecture to USPTO on advanced photonics
    Date: May 4, 2022
    MERL Contact: Toshiaki Koike-Akino
    Research Areas: Artificial Intelligence, Communications, Electronic and Photonic Devices, Machine Learning, Optimization, Signal Processing
    Brief
    • Toshiaki Koike-Akino gave an invited lecture on advanced photonic devices at the United States Patent and Trademark Office (USPTO) Technology Fair on May 4, 2022. Topics of the lecture included the recent progress of applied artificial intelligence (AI) technologies for optical systems, nano-photonic devices, and quantum technology. During the 2-hour interactive online presentation, he lectured to more than 200 patent examiner participants.

      USPTO Tech Fair Organizer mentioned:
      "Thank you very much for representing Advanced Photonic Devices at this year’s Technology Center 2800 Virtual Tech Fair held May 4th, 2022. Tech Fair is an important part of the United States Patent and Trademark Office’s Patent Examiner Technical Training Program (PETTP). Having a scientifically well-trained examiner workforce and ensuring the quality, consistency, and reliability of issued patents are top priorities at the USPTO. The PETTP is designed to achieve those priorities by giving examiners direct access to technical experts who are willing to share their knowledge about prior art and industry standards for both emerging and established technologies. Experts like yourself help to maintain our high quality of patent examination by keeping examiners updated on technologies and innovations pertinent to their field of examination.
      We very much appreciate your efforts, time, and contributions."
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  •  TALK    [MERL Seminar Series 2022] Prof. Michael Posa presents talk titled Hybrid robotics and implicit learning
    Date & Time: Tuesday, May 3, 2022; 1:00 PM
    Speaker: Michael Posa, University of Pennsylvania
    MERL Host: Devesh K. Jha
    Research Areas: Control, Optimization, Robotics
    Abstract
    • Machine learning has shown incredible promise in robotics, with some notable recent demonstrations in manipulation and sim2real transfer. These results, however, require either an accurate a priori model (for simulation) or a large amount of data. In contrast, my lab is focused on enabling robots to enter novel environments and then, with minimal time to gather information, accomplish complex tasks. In this talk, I will argue that the hybrid or contact-driven nature of real-world robotics, where a robot must safely and quickly interact with objects, drives this high data requirement. In particular, the inductive biases inherent in standard learning methods fundamentally clash with the non-differentiable physics of contact-rich robotics. Focusing on model learning, or system identification, I will show both empirical and theoretical results which demonstrate that contact stiffness leads to poor training and generalization, leading to some healthy skepticism of simulation experiments trained on artificially soft environments. Fortunately, implicit learning formulations, which embed convex optimization problems, can dramatically reshape the optimization landscape for these stiff problems. By carefully reasoning about the roles of stiffness and discontinuity, and integrating non-smooth structures, we demonstrate dramatically improved learning performance. Within this family of approaches, ContactNets accurately identifies the geometry and dynamics of a six-sided cube bouncing, sliding, and rolling across a surface from only a handful of sample trajectories. Similarly, a piecewise-affine hybrid system with thousands of modes can be identified purely from state transitions. Time permitting, I'll discuss how these learned models can be deployed for control via recent results in real-time, multi-contact MPC.
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  •  NEWS    Radu Corcodel to present invited seminar at NYU on Robot Vision
    Date: May 4, 2022
    MERL Contact: Radu Corcodel
    Research Areas: Computer Vision, Robotics
    Brief
    • Radu Corcodel, a Principal Research Scientist in MERL's Computer Vision Group, will present an overview of the Robot Perception research published by MERL for advanced manipulation. The talk will mainly cover topics pertaining to robotic manipulation in unstructured environments such as machine vision, tactile sensing and autonomous grasping. The seminar will also cover specific perception problems in non-prehensile interactions such as Contact-Implicit Trajectory Optimization and Tactile Classification, and is intended for a broader audience.
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  •  NEWS    MERL's Yanting Ma completed the 2022 Boston Marathon
    Date: April 18, 2022
    Where: Boston, MA
    MERL Contact: Yanting Ma
    Brief
    • Researcher, Yanting Ma, qualified for and completed the Boston Marathon on Monday April 18th. We would like to congratulate her on achieving this personal goal in an impressive time of 3:18.48!!
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  •  TALK    [MERL Seminar Series 2022] Prof. Sebastien Gros presents talk titled RLMPC: An Ideal Combination of Formal Optimal Control and Reinforcement Learning?
    Date & Time: Tuesday, April 12, 2022; 11:00 AM EDT
    Speaker: Sebastien Gros, NTNU
    MERL Host: Rien Quirynen
    Research Areas: Control, Dynamical Systems, Optimization
    Abstract
    • Reinforcement Learning (RL), similarly to many AI-based techniques, is currently receiving a very high attention. RL is most commonly supported by classic Machine Learning techniques, i.e. typically Deep Neural Networks (DNNs). While there are good motivations for using DNNs in RL, there are also significant drawbacks. The lack of “explainability” of the resulting control policies, and the difficulty to provide guarantees on their closed-loop behavior (safety, stability) makes DNN-based policies problematic in many applications. In this talk, we will discuss an alternative approach to support RL, via formal optimal control tools based on Model Predictive Control (MPC). This approach alleviates the issues detailed above, but also presents some challenges. In this talk, we will discuss why MPC is a valid tool to support RL, and how MPC can be combined with RL (RLMPC). We will then discuss some recent results regarding this combination, the known challenges, and the kind of control applications where we believe that RLMPC will be a valuable approach.
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  •  TALK    [MERL Seminar Series 2022] Albert Benveniste, Benoît Caillaud, and Mathias Malandain present talk titled Exact Structural Analysis of Multimode Modelica Models
    Date & Time: Tuesday, April 5, 2022; 11:00 AM EDT
    Speaker: Albert Benveniste, Benoît Caillaud, and Mathias Malandain, Inria
    MERL Host: Scott A. Bortoff
    Research Areas: Dynamical Systems, Multi-Physical Modeling
    Abstract
    • Since its 3.3 release, Modelica offers the possibility to specify models of dynamical systems with multiple modes having different DAE-based dynamics. However, the handling of such models by the current Modelica tools is not satisfactory, with mathematically sound models yielding exceptions at runtime. In our introduction, will briefly explain why and when the approximate structural analysis implemented in current Modelica tools leads to such errors. Then we will present our multimode Pryce Sigma-method for index reduction, in which the mode-dependent Sigma-matrix is represented in a dual form, by attaching, to every valuation of the sigma_ij entry of the Sigma matrix, the predicate characterizing the set of modes in which sigma_ij takes this value. We will illustrate this multimode analysis on example, by using our IsamDAE tool. In a second part, we will complement this multimode DAE structural analysis by a new structural analysis of mode changes (and, more generally, transient modes holding for zero time). Also, mode changes often give raise to impulsive behaviors: we will present a compile-time analysis identifying such behaviors. Our structural analysis of mode changes deeply relies on nonstandard analysis, which is a mathematical framework in which infinitesimals and infinities are first class citizens.
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