Penn Engineering Events

ASSET Seminar: "What’s In my Network? On Learned Proximals and Testing for Explanations"
2024-11-06 12:00 - 13:15 (America/New_York) | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Abstract:
Modern machine learning methods are revolutionizing what we can do with data, from tiktok video recommendations to biomarkers discovery in cancer research. Yet, the complexity of these deep models makes it harder to understand what functions these data-dependent models are computing, and which features they detect regarding as important for a given task. In this talk, I will review two approaches for turning general deep learning models more interpretable, both in an unsupervised setting in the context of imaging inverse problems—through learned proximal networks—as well as in supervised classification problems for computer vision—by testing for the semantic importance of concepts via betting.
Zoom Link (if unable to attend in-person): https://upenn.zoom.us/j/96232340757

CBE Doctoral Dissertation Defense: "Scaling Mineral Carbonation and Critical Mineral Recovery in Mining Waste: Process Engineering, Techno-Economics, and Public Policy" (Katherine Vaz Gomes)
2024-11-06 13:00 - 15:00 | Room 35, Singh Center for Nanotechnology, 3205 Walnut Street, Philadelphia, PA, 19104, United States
Abstract:
The growing need to secure critical minerals for clean energy technologies, alongside the urgency to mitigate climate change, presents a unique opportunity to combine mineral recovery with carbon sequestration. This dissertation explores the potential of mine tailings as a dual-purpose feedstock, enabling both the extraction of critical minerals and the storage of CO₂ through mineral carbonation. Mine tailings, typically an industrial byproduct, offer a promising source of magnesium and calcium, which can react with CO₂ to form stable carbonate minerals, providing a means of permanent carbon storage while recovering valuable resources.
This research focuses on optimizing CO₂ mineralization in four types of legacy tailings: platinum group element tailings, basalt tailings, and two sources of asbestos waste. Tailings were characterized to evaluate their mineralogical composition and their potential for mineral recovery and carbonation. The study involved a series of thermal and chemical extraction experiments aimed at maximizing the release of magnesium and other critical minerals while improving carbonation efficiency. The results show varying extraction efficiencies across different tailings, with asbestos tailings achieving the highest magnesium recovery (80%). Performance differences among tailings are discussed in relation to their mineralogical structure, reactive surface area, and porosity.
A techno-economic analysis (TEA) was conducted to evaluate the costs and benefits of integrating critical mineral recovery with CO₂ sequestration in industrial settings. The analysis revealed that while mineral carbonation offers a viable method for reducing CO₂ emissions, its economic feasibility depends heavily on feedstock characteristics, processing conditions, and market demand for the recovered minerals. Key cost factors include reagent consumption, energy requirements, and the specifications of equipment needed to manage corrosive materials and high-pressure environments.
The policy implications of these findings are also examined, particularly in the context of the U.S. Superfund law (CERCLA) and the Resource Conservation and Recovery Act (RCRA), which regulate industrial waste management and provide incentives for CO₂ capture and storage (CCS) technologies. Policy recommendations center on updating regulatory frameworks to encourage the use of legacy waste streams for both critical mineral recovery and carbon sequestration, potentially advancing global energy transition and climate mitigation goals.
This dissertation concludes by highlighting the importance of cross-sector collaboration in promoting the advancement of carbon mineralization technologies. Future research should prioritize scaling up integrated processes, improving material handling, and addressing both environmental and economic challenges. By utilizing mine tailings for critical mineral recovery and carbon storage, this work contributes to the broader effort to build sustainable, circular economies that address both resource security and climate change.

Fall 2024 GRASP SFI: Jason Ma, University of Pennsylvania, "Environment Curriculum Generation via Large Language Models"
2024-11-06 15:00 - 16:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This will be a hybrid event with in-person attendance in Levine 307 and virtual attendance on Zoom.
ABSTRACT
Recent work has demonstrated that a promising strategy for teaching robots a wide range of complex skills is by training them on a curriculum of progressively more challenging environments. However, developing an effective curriculum of environment distributions currently requires significant expertise, which must be repeated for every new domain. Our key insight is that environments are often naturally represented as code. Thus, we probe whether effective environment curriculum design can be achieved and automated via code generation by large language models (LLM). In this paper, we introduce Eurekaverse, an unsupervised environment design algorithm that uses LLMs to sample progressively more challenging, diverse, and learnable environments for skill training. We validate Eurekaverse’s effectiveness in the domain of quadrupedal parkour learning, in which a quadruped robot must traverse through a variety of obstacle courses. The automatic curriculum designed by Eurekaverse enables gradual learning of complex parkour skills in simulation and can successfully transfer to the real-world, outperforming manual training courses designed by humans.

CBE Seminar: "AI-Guided Closed-Loop Discovery of Photostable Light-Harvesting Molecules" (Charles Schroeder, UIUC)
2024-11-06 15:30 - 16:30 | Wu & Chen Auditorium
Abstract:
AI–guided closed-loop experimentation has recently emerged as a promising method to optimize functional properties in materials discovery. However, achieving the full potential of this approach in the chemical sciences requires new methods to efficiently access large chemical spaces. In this talk, I will discuss a closed-loop approach combining automated synthesis, materials characterization, and AI-guided prediction methods to identify organic light-harvesting molecules with optimized photostability. A Bayesian optimization framework is used to efficiently guide the search through a large molecular space using key physicochemical descriptors while maintaining a customizable tradeoff between exploitative and explorative sampling. Candidate molecules suggested by the AI framework are prepared via automated synthesis using a modular, “Lego-like” molecular building block approach based on Suzuki cross-coupling, followed by characterization of photophysical properties. Our results show that high-energy regions of the triplet state manifold are key to controlling molecular photostability in solution across a diverse chemical library of light-harvesting donor-bridge-acceptor oligomers. Remarkably,this insight emerged after automated synthesis and experimental characterization of only ~1.5% of the total chemical space of 2,200oligomers. In the second part of the talk, I will discuss emerging directions including the extension of this framework to the design and development of function-encoded molecular building blocks to enhance photostability and the discovery of new organic electrochromic materials. Overall, this work shows that interfacing physics-based modeling with closed-loop discovery campaigns – unimpeded by synthesis bottlenecks – can rapidly illuminate fundamental chemical insights and guide rational pursuit of frontier molecular

David P. Pope Distinguished Lecture: "Supersonic Collisions of Microparticles on Metal: In-Situ Studies at the Nanosecond and Micrometer Scales"
2024-11-07 10:30 - 12:00 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
There are many situations in which small particles impact metals at high speeds, even above the speed of sound. Sometimes these are unintentional (as for foreign object damage or micrometeorite strikes), and sometimes they occur by design (as for surface treatment processes like abrasive spray, peening, or spray coatings). The fundamental physics behind supersonic impacts, however, remain mysterious; the impacts are extremely fast and involve microscopic particles, so that they are challenging to resolve. This talk will review a new line of research aimed at understanding the unit process of particle impacts at velocities into the supersonic range—we study individual ~5-50 µm particles and record their approach and impact with a substrate using an all-optical single-particle test method with nanosecond time resolution. For hard particles, this method leads to quantitative measures of plasticity at extreme rates (>107 s -1). In this range, conventional plasticity gives way to ballistic dislocation motion, with counterintuitive “anti-thermal” behavior in which hotter metals are stronger. For metallic particles, our approach quantitatively reveals the changes in plasticity that occur as particles approach the threshold velocity for bonding, as well as other deleterious transitions such as impact-induced melting and erosion.

ESE Fall Seminar - "The Circuit Frontier: Innovating and Expanding ASIC Solutions for Enhanced Biosensing and Seamless Wireless Communication"
2024-11-07 11:00 - 12:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
The BU Wireless Integrated Systems and Extreme Circuits (WISE-Circuits) group blends integrated circuits with energy-constrained applications to pioneer breakthroughs in information theory, bioengineering, and communications. Our research focuses on the development of Cyber-Secure Biological Systems, leveraging living sensors constructed from engineered biological entities seamlessly integrated with solid-state circuits. This unique synergy harnesses the advantages of biology while incorporating the reliability and communication infrastructure of electronics, offering a unique solution to societal challenges in healthcare and environmental monitoring.
Additionally, our research extends to the realm of all-in-one data decoders, where we employ novel cross-layer techniques spanning algorithms to low-power integrated circuits. This innovative decoding approach facilitates ultra-low-energy wireless communications, a critical requirement for the success of these systems and numerous other applications. In this seminar, I will delve into the intricacies of our interdisciplinary approach and the longer-term vision of the WISE-Circuits research, spotlighting the potential of energy-efficient integrated circuits in the domains of biosensing and wireless communications. These collaborative research projects involve MIT BE/MechE, BU ECE/BME, and MIT RLE-Northeastern University.

CIS Seminar: "Cedar: A language for expressing fast, safe, and fine-grained authorization policies"
2024-11-07 15:30 - 16:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Cedar is a new open-source authorization policy language, used to express fine-grained permissions on behalf of applications. Rather than embed authorization logic in their application code, developers can write that logic as Cedar policies and delegate access requests to Cedar’s evaluation engine. Cedar is designed to be ergonomic, fast, safe, and analyzable. Cedar’s simple and intuitive syntax supports common authorization use-cases, naturally leveraging concepts from role-based, attribute-based, and relation-based access control models. Cedar’s policy structure ensures that access requests can be authorized quickly. Cedar’s schema-based policy validator leverages optional typing to help policy writers avoid mistakes, but not get in their way. Cedar’s design has been finely balanced to allow for a sound and complete logical encoding to a decidable first-order theory, which enables precise automated policy analysis, e.g., to ensure that when refactoring a set of policies, the authorized permissions do not change.
Cedar is built using a high-assurance process called verification-guided development. Its authorization engine and validator are formally modeled in the Lean proof-enabled programming language. Cedar’s core development team proves safety and security properties about those models in Lean, and runs millions of automated differential tests to check that the implementations of the Cedar authorization engine and validator, written in Rust, agree with the Lean models.
Cedar is used by AWS’s Amazon Verified Permissions and AWS Verified Access services, and in third-party applications and services. Cedar’s code, proofs, and tests are open-source at https://github.com/cedar-policy. There are many interesting problems still to address, especially in the areas of provable, end-to-end security enforcement; automated specification and test generation; and formal reasoning about how policies can evolve.

Fall 2024 GRASP on Robotics: Nicholas Roy, Massachusetts Institute of Technology, "Hierarchy, Abstractions and Geometry"
2024-11-08 10:30 - 11:45 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This will be a hybrid event with in-person attendance in Wu and Chen and virtual attendance on Zoom.
ABSTRACT
In the last few years, the ability for robots to understand and operate in the world around them has advanced considerably. Examples include the growing number of self-driving car systems, the considerable work in robot mapping, and the growing interest in home and service robots. However, one limitation is that robots most often reason and plan using very geometric models of the world, such as point features, dense occupancy grids and action cost maps. To be able to plan and reason over long length and timescales, as well as planning more complex missions, robots need to be able to reason simultaneously about the abstract representations needed to support task planning, as well as the detailed geometry for reliable motion. I will talk about recent work in joint reasoning about semantic representations and physical representations and what these joint representations mean for planning and decision making.

MEAM Ph.D. Thesis Defense: "Exploring Multimodal Sensing Across the Stack for Robot Manipulation"
2024-11-11 11:00 - 12:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Despite substantial progress in robotics, achieving human-like manipulation remains a significant challenge. Existing robotic systems typically leverage human-inspired sensory modalities: vision, touch, and proprioception. However, these modalities are historically studied and integrated in isolation, leading to limited performance in complex real-world tasks that require sensing across multiple modalities for robust generalization. As a result, robots have struggled to transition from structured lab environments to effective real-world applications.
This persistent challenge highlights two critical limitations: the narrow focus on only human-inspired senses and the isolated integration of vision, touch, and proprioception fail to provide robots with the necessary adaptability for the real world. In contrast to traditional approaches focused on each of these three modalities, complementary modalities and tightly integrated multimodal systems are underexplored. With the unprecedented availability of diverse off-the-shelf sensors, powerful on-board computation to process rich data streams, advances in data-driven control and perception frameworks, and a new spotlight on robotic system integration, we now face a unique opportunity to construct new multimodal sensing paradigms.
This thesis explores three complementary aspects of multimodality selection and integration across sensor design, perception, and RL control. First, we address the challenge of integrating an additional modality without compromising existing functionality – a sensing mechanism design problem that often forces trade-offs between different sensing modes. We leverage a selectively transmissive membrane to enable proximity depth sensing that seamlessly augments the visuotactile modality. Next, we exploit the complementary nature of our sensor’s dual modalities for sensor fusion. We demonstrate how carefully combining proximity and tactile modalities can enhance perception, enabling more robust and informative contact patch detection. Finally, we bridge the reality gap in robot policy learning, where sim-to-real transfer is particularly challenging due to the complex physics of contact-rich manipulation. By developing a sim-to-real tactile skin model, we achieve zero-shot transfer of tactile data during the in-hand translation task, allowing us to evaluate the impact of combining tactile feedback with proprioception in this dexterous control task.

Center for Soft and Living Matter Seminar: "Medium-range Order and Local Structure Fluctuations in Metallic Glass"
2024-11-11 12:30 - 13:30 | DRL 2N3
Amorphous materials have no long-range order, but there are ordered structures at short-range (2-5 Å), medium-range (5-20 Å), and even longer-length scales. While regular and semiregular polyhedra are often identified as short-range order in amorphous materials, the nature of the medium-range order has remained elusive. Because of the disorder, the dynamics also become far more complicated. For example, the vibrational spectrum of glasses shows an excess density of states. This is known as the Boson Peak and has been found to be a ubiquitous feature of amorphous materials. In this talk, I will present recent studies of metallic glass using neutron and synchrotron X-ray scattering. The development of medium-range order in driving liquid-to-liquid phase transitions will be highlighted. For the dynamics, the momentum dependence of the inelastic scattering intensity reveals spatial correlation at different time scales. The role of local structure fluctuations will be discussed.

MEAM Ph.D. Thesis Defense: "Coupling Hard and Soft Interfaces to Realize Actuators and Energy Sources that Bring Robots Towards Animal Mobility"
2024-11-11 13:00 - 14:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Mobile robots have shown significant advancements in agility, intelligence, and efficiency over the past few decades. However, their endurance and overall performance remain limited by the onboard power supplies. Current power sources typically restrict mobile robots to areas close to the electrical grid and necessitate heavier batteries for extended range. Energy refueling could be significantly challenging in remote and inaccessible regions, and traditional energy harvesting methods have also proven inadequate for sustaining continuous operations.
To address this challenge, we propose a bio-inspired approach: enabling robots to “digest” energy-dense metals for power generation, analogous to how animals process food for energy. This concept builds upon aluminum-air batteries, which operate as miniature chemical plants converting aluminum into electricity. We selected this technology for three key advantages: (1) exceptional energy density for improved endurance compared to conventional lithium batteries; (2) simple anode replacement for rapid refueling without charging stations; and (3) readily available fuel sources from everyday aluminum materials, from beverage cans to construction waste.
This thesis investigates how aluminum-air batteries can benefit the robotics community through four interconnected studies. First, we quantify the energy gap between mobile robots and their biological counterparts through comparative analysis of energy and power density, establishing benchmarks for future battery technologies to achieve biological equivalence. Second, we demonstrate the development of a highly stretchable metal-air battery using sliding electrodes, achieving up to 10-fold improvements in areal capacity and power compared to existing stretchable designs, which could extend the endurance and unleash the potential of various soft robots and wearable technologies. Third, we implement customized metal-air batteries on an Arduino-based robot platform, demonstrating continuous operation through metal oxidation using various aluminum and zinc sources while addressing challenges such as byproduct accumulation, hydrogen production, and water consumption. Finally, we showcase a feasible approach to develop a soft crawler based on this metallivore concept, capable of simultaneous metal digestion and continuous locomotion. By developing this aluminum-air battery-based energy solution, we demonstrate a path toward extending robots’ operational range and endurance beyond current limitations, thereby expanding their potential in remote and complex environments.

Tedori-Callinan Distinguished Lecture: "Novel Passive and Active Approaches to Fluid Friction Reduction using Polymers & Plastrons"
2024-11-12 10:15 - 11:15 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
When a superhydrophobic (SH) textured surface is immersed in water it traps a thin shiny layer of air within the texture that is known as a plastron. Contact line pinning stabilizes this Cassie-Baxter state and the patches of air trapped in the texture can act as shear-free regions that locally lower the frictional dissipation. Recent developments of scalable manufacturing methods for producing robust SH surfaces open new possibilities for using these textures in drag reduction applications. We use a newly-developed bespoke Taylor-Couette (TC) apparatus to compare and contrast frictional drag reduction by dilute polymer solutions and superhydrophobic (SH) surfaces in turbulent flows for Reynolds numbers over a wide range (10,000 < Re < 100,000). By applying SH coatings to the inner rotating cylinder, we can evaluate the drag reducing performance and robustness of different textures and calculate the effective slip length in turbulent flow using a suitably augmented Prandtl-von Kármán (PvK) analysis. We also investigate how these plastrons can be partially stabilized against turbulent pressure fluctuations using active heating as well as chemical methods to locally regenerate vapor. Additionally, we can use our apparatus to revisit an alternative drag-reducing strategy using dilute solutions of various high molecular weight polymers. We show that natural polysaccharides derived from plant mucilage can be an inexpensive and effective alternative to costly synthetic polymers, whilst still approaching the same maximum drag reduction (MDR) asymptote. Finally, we explore combinations of these two complementary drag reduction methods – one arising from wall slip and the other due to changes in turbulence dynamics in the bulk flow – and find that the two effects are not always additive; interestingly, the effectiveness of polymer drag reduction can actually be reduced in the presence of a SH coating on the wall.

ESE Fall Seminar - "Color center photonics in silicon carbide: scalable fabrication, cryogenic experiments, and quantum simulation on NISQ testbeds"
2024-11-12 11:00 - 12:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Color center systems are among the leading platforms in the development of quantum communication and quantum sensing hardware due to their desirable spin, optical, and spin-photon properties. Among them, the near infrared emitters in silicon carbide, such as the nitrogen-vacancy center in 4H-SiC, provide fiber-friendly operation in an industrially mature substrate, ideal for scalable deployment of quantum networking hardware. By exploring the triangular geometry in quantum-grade SiC, we develop the first wafer-scale fabrication process for color center photonics based on ion beam etching at an angle, realizing a broad range of devices for guiding and resonating light.
Due to their near-identical emission, color centers enable unprecedented studies of multi-emitter-cavity physics, or the Tavis-Cummings (TC) model, with applications in quantum light generation and quantum memories. Here, a lossy resonator interacts with multiple quantum emitters in resonant and off-resonant systems. Modeling of TC systems in an open quantum setting is limited to small dimensions on classical computing resources. We explore how quantum computers can help bridge this knowledge gap and propose algorithms for quantum mapping, analog and digital simulation of the TC model on superconducting and trapped ion DOE testbeds.

MEAM Ph.D. Thesis Defense: "Impulse-Induced Nonlinear Dynamics of Flexible Mechanical Metamaterials"
2024-11-13 10:00 - 11:00 | Room 2C2, David Rittenhouse Laboratory Building, 209 S. 33rd Street, Philadelphia, PA, 19104, United States
Mechanical metamaterials are artificially designed structures that exhibit unique properties due to their internal structure rather than their composition, e.g., negative Poisson’s ratio, tunable stiffness, and advanced thermal characteristics. While the static properties of mechanical metamaterials have been widely studied, their nonlinear dynamics remain largely unexplored, which could pave ways for innovative design and optimization for novel applications related to deployable structures, reconfigurable robots, and more. This dissertation aims to expand the fundamental understanding of flexible mechanical metamaterials through the combination of analytical, numerical, and experimental methods. This thesis is divided into three areas: the triggering of phase transitions through the collision of vector solitons in a multistable structure comprising rotating squares, the exploration of asymptotic energy propagation in a flexible Kagome lattices, and the development of a bio-inspired pulse-driven flexible platform for rapid motion control of underactuated systems. These studies demonstrate that mechanical metamaterials possess rich nonlinear dynamical behaviors, including soliton collisions leading to phase transitions, the preservation and disruption of topological modes under nonlinear loading, and spatiotemporal dynamics that can be applied toward stabilization of robots subjected to sudden loads.

ESE Fall Seminar - "Algorithmic Bias in Computer Vision - Generative Methods Enable the Experimental Approach"
2024-11-13 10:30 - 11:30 | Wu & Chen Auditorium
As Artificial Intelligence (AI) finds increasing applications in industry and society. Responsible deployment demands that we measure and correct algorithmic biases vis-a-vis protected attributes such as sex, age and ethnicity. State of the art methods for measuring algorithmic bias rely on test sets that are collected in the wild and are then annotated for the protected attributes. Such methods are therefore observational and yield correlational information. I will argue that in order to obtain useful information to discover and correct biases we need causal information which is only available if we use an experimental method. I will show that modern generative models offer a promising starting point to develop experimental testing methods. I will review our recent work in face synthesis and demonstrate its application to the study of algorithmic bias in gender classification, face recognition, and social judgment of faces.

ASSET Seminar: "Multi-Omic Approaches for Deciphering Cellular Heterogeneity and Plasticity in Cancer"
2024-11-13 12:00 - 13:15 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Abstract:
Tumors are complex and heterogeneous systems, which challenge their classification and treatment. The Silverbush lab decodes tumor heterogeneity and plasticity to understand how cancer cells transform to become more aggressive or evade treatment. We particularly examine hard-to-treat cancers with high heterogeneity, focusing on the notorious kings of heterogeneity and aggressiveness: brain cancers. To achieve this goal, we develop computational multi-omic single-cell tools. These tools enable us, for the first time, to simultaneously measure DNA methylation, point mutations, and transcriptional activity in the same single cells. We then use these tools to study patient samples, often treated with innovative clinical trials, and build solutions to understand whom the treatment can help, how to improve it, and what the optimal time window is for administering it.
Zoom Link (if unable to attend in-person): https://upenn.zoom.us/j/96390831586

Introduction to COMSOL Multiphysics® Workshop
2024-11-13 14:00 - 15:30 | PICS Conference Room 534 – A Wing , 5th Floor, 3401 Walnut Street, Philadelphia, PA, 19104, United States
We are excited to announce that COMSOL will be coming to the University of Pennsylvania for a free special event. On November 13th at 2pm we will be providing a Introduction to COMSOL Multiphysics® Workshop on campus at 3401 Walnut Street Wing A, Conference Room 534, 5th Floor.

At this workshop, you will see the capabilities and workflow of the COMSOL Multiphysics® software and learn through a guided hands-on exercise. You will leave with some new skills to work on your own applications using a free two-week COMSOL Multiphysics trial.

We are excited to meet with you and discuss your simulation interests. Please bring along all of your questions and any interested colleagues!

You can register and find more details on the event at the page below:
https://www.comsol.com/events/workshop/introduction-to-comsol-multiphysics-workshop-for-upenn-123252

Fall 2024 GRASP SFI: Noémie Jaquier, Karlsruhe Institute of Technology, “The geometric side(s) of Lagrangian dynamics”
2024-11-13 15:00 - 16:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This will be a hybrid event with in-person attendance in Levine 307 and virtual attendance on Zoom. This week’s speaker will be virtual.
ABSTRACT
Lagrangian mechanics provides a powerful framework for modeling the dynamics of physical systems by inferring their motions based on energy conservation. This talk will explore recent advances in applying geometric perspectives, particularly Riemannian geometry, to Lagrangian principles for predicting and optimizing motion dynamics. First, I will discuss how the dynamic properties of humans and robots are straightforwardly accounted for by considering geometric configuration spaces. Second, I will show how this geometric approach can be extended to generate dynamic-aware, collision-free robot motions by modifying the underlying Riemannian metric. Finally, I will consider the problem of learning unknown high-dimensional Lagrangian dynamics. I will present a geometric architecture to learn physically-consistent and interpretable reduced-order dynamic parameters that accurately capture the behavior of the original system.

ESE Guest Seminar - "Coherent Control of Electromagnetic Waves via Tunable Chaotic Cavities"
2024-11-14 10:30 - 11:30 | Towne 337
The theory of Coherent Perfect Absorption1 (time-reversed lasing) and Reﬂectionless Scattering Modes2 has shown that there always exist discrete solutions to scattering of electromagnetic waves in multiple-scattering geometries that achieve perfect transduction or perfect (reﬂectionless) impedance matching. In general these are transient (complex frequency) solutions, but, typically, with tuning of a one system parameter it is possible to achieve steady- state, reﬂectionless excitation of arbitrary systems. Here we focus on the case of reﬂectionless excitation of a lossless multiport/multi-channel system, and show3 that it is possible not only to eliminate reﬂection, but also to control the scattering into the output channels to perform routing or ﬁltering functions. This is achieved by creating a degeneracy of d complex eigenvalues of the wave equation, tuned to the real frequency; and we ﬁnd that the number of tuning parameters needed to achieve such routing at a given frequency to be 2(d+1). For heuristic reasons we expect an open low-loss wave-chaotic cavity with tunable scattering elements to be optimal for achieving routing functions, since such a cavity has overlapping, pseudo-random resonances, making it frequency agnostic, and easily reprogrammable. We will present the results of recent experiments4 and simulations3,4 of such a cavity that have conﬁrmed this conjecture in the microwave frequency range. These systems are easily reprogrammable, making them uniquely eﬀective for applications where frequency- agile performance is required and implying robustness to perturbations and defects in fabrication.

“Coherent Perfect Absorbers: Time-reversed Lasers”, D. Chong, L. Ge, H. Cao, and A. D. Stone, Physical Review Letters, 105, 053901 (2010).
“Theory of Reﬂectionless Scattering Modes”, William Sweeney, Chia Wei Hsu, and A. Douglas Stone, Phys. Rev. A, 2020, https://link.aps.org/doi/10.1103/PhysRevA.102.063511
“Coherent Control of Scattering of Guided Waves”, in preparation, A. Alhulaymi, Pyvovar, P. Del Hougne, O. D. Miller, A. D. Stone.
“Agile Free-Form Signal Filtering with a Chaotic-Cavity-Backed Non-Local Programmable Metasurface”, T. Faul, L. Cronier, A. Alhulaymi, A. D. Stone, P. del Hougne, submitted to Advanced Materials.

MSE Seminar: "Luminescent Photonic Metamaterials and Devices From THz to Optical Frequencies"
2024-11-14 10:30 - 12:00 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
A crucial yet unavailable component in high-performance photonic integrated circuits (ICs) and other chip-scale photonic systems is an on-chip light source that is efficient, functional, IC-compatible, and electronically addressable. In this talk, I will cover several types of on-chip sources, including perovskite microlasers and luminescent hyperbolic metamaterials, topologically protected microlasers on the III-V platform, as well as spintronic THz emitters on the III-N platform.

Fall 2024 GRASP Seminar: James Bern, Williams College, "Mixed Reality Soft Robots and Accessible CAD Software"
2024-11-14 11:00 - 12:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
*This seminar will be held in-person in Levine 307 as well as virtually via Zoom. This seminar will NOT be recorded.
ABSTRACT
This talk has two parts. First, I will explain our recent work on making it easier to control 3D soft robots. By extending our prior work on soft robot inverse kinematics (Soft IK) into virtual reality (VR), we realize an intuitive, real-time posing pipeline for arbitrary 3D soft robots. This pipeline promises to extend to mixed reality applications. Second, I will introduce a new experimental CAD program called Conversation. Conversation enables novice users to quickly design simple 3D-printed machines. The software features a unique workflow (2D sketch and 3D part remain separate), utilizes an unconventional mesh-based geometry kernel (Manifold), and is very fast (go from DXF to STL in seconds – minutes) and very small (executable weighs ~1 MB). It is also a promising target for new computational design algorithms.

Research + Innovation Seminar Series - Sponsored Research
2024-11-14 12:00 - 13:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States

Fall 2024 GRASP on Robotics: Damion Shelton, Agility Robotics, “What do we want from our machines?”
2024-11-15 10:30 - 11:45 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This will be a hybrid event with in-person attendance in Wu and Chen and virtual attendance on Zoom.
ABSTRACT
In 2022 I represented Agility Robotics at the first “Philadelphia Summit” on the weaponization of autonomous robots, co-hosted by the GRASP lab and Boston Dynamics. By late fall, this yielded a joint statement, signed by Agility, Boston Dynamics, and others, with the self-explanatory title “General Purpose Robots Should Not Be Weaponized”. But why general purpose robots? And why now? After that summit, a follow-up conference, “Ethical and Legal Dilemmas of Autonomous Weapons in War and National Security”, was hosted by CERL in 2024, against the backdrop of the Ukraine war and growing public awareness of the role of drones and other semi-autonomous weapons systems. While this event has not (yet) yielded a specific industry response, it further refines the concept of perceived harm from 2022 by adding the explicit call-out that the ethical and legal dilemmas of mobile robots are inseparably tied to autonomy. Further, virtually the entirety of modern generative AI awareness, including among industry experts, has come to pass since the original 2022 event.
The purpose of this talk is twofold. First, humanoid robots – since they look like us, occupy our spaces, and are able to perform tasks in a manner similar to us – are the ultimate instantiation of “general purpose” robots. What are the ethical, legal, and social implications of this sort of technology? Are robots like Digit actually different from a pick and place machine, or a Roomba? And second, does this situation change when you add advanced AI?
Over and above the focus of the 2022 and 2024 summits, this talk will evaluate a broader set of axes than just robots as weapons. Since we are still in the early days of both modern AI and commercialized humanoid robots, we have the opportunity to ask a more general question: “What do we want from our machines?”

ESE 2024 Jack Keil Wolf Lecture - "Army of Ants: The Power of Working in Concert"
2024-11-15 16:00 - 17:15 | Glandt Forum, Singh Center for Nanotechnology, 3205 Walnut Street, Philadelphia, PA, 19104, United States
Synchronized operation of a large number of similar entities can generate behavior that cannot be expected from single one. This principle combined with the physical concept of coherence in waves enables creation of programmable 3-dimensional focal points that can be used to enable many applications such as wireless energy transfer at distance on earth and even from space, flat lensless projectors and cameras, and various other present and future applications. It can manifest itself in the form of phased arrays and focusing arrays with an ensemble of synchronized wave generating or receiving elements. While the individual element behavior may be rather unremarkable, such systems can lead to rich and useful behaviors. We will go through a journey based on this principle and a progression of its potential applications in an increasing order of outlandishness.

Fall 2024 GRASP Seminar: Yunzhu Li, Columbia University, “Foundation Models for Robotic Manipulation: Opportunities and Challenges”
2024-11-18 11:00 - 12:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
*This seminar will be held in-person in Levine 307 as well as virtually via Zoom.
ABSTRACT
Foundation models, such as GPT-4 Vision, have marked significant achievements in the fields of natural language and vision, demonstrating exceptional abilities to adapt to new tasks and scenarios. However, physical interaction—such as cooking, cleaning, or caregiving—remains a frontier where foundation models and robotic systems have yet to achieve the desired level of adaptability and generalization. In this talk, I will discuss the opportunities for incorporating foundation models into classic robotic pipelines to endow robots with capabilities beyond those achievable with traditional robotic tools. The talk will focus on three key improvements in (1) task specification, (2) low-level, and (3) high-level scene modeling. The central idea behind this research is to translate the commonsense knowledge embedded in foundation models into structural priors that can be integrated into robot learning systems. This approach leverages the strengths of different modules (e.g., VLM for task interpretation and constrained optimization for motion planning), achieving the best of both worlds. I will demonstrate how such integration enables robots to interpret instructions provided in free-form natural language, and how foundation models can be augmented with additional memory mechanisms, such as an action-conditioned scene graph, to handle a wide range of real-world manipulation tasks. Toward the end of the talk, I will discuss the limitations of the current foundation models, challenges that still lie ahead, and potential avenues to address these challenges.

ESE Ph.D. Thesis Defense: "Learning-based Model Predictive Control for Aerial Vehicles"
2024-11-18 14:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Learning-based model predictive control (MPC) is an increasingly prominent control paradigm in recent years. One primary approach in learning-based MPC is to leverage machine or deep learning tools to construct accurate dynamics models. These models are then deployed into optimization-based control schemes. Although these frameworks can potentially provide significant performance improvements, a number of key challenges need to be addressed before they can realize their full potential and prove reliable for real-world applications. In this defense, I highlight a set of frameworks that alleviate these challenges in a systematic and holistic manner.
The data-driven models within learning-based MPC frameworks aim to strike a balance between architectural complexity and expressiveness. However, many of these models either have elaborate architectures, or lack sufficient expressiveness to capture the intricate interactions and nonlinearities within the system dynamics. As the first contribution of this defense, I outline a novel learning-based MPC framework that addresses this balance. In particular, I show how an accurate and architecturally simple dynamics model can be constructed by combining prior knowledge of the system with a data-driven component. This combined model is lightweight, making it highly compatible with nonlinear MPC. Another challenge in learning-based MPC frameworks is that the dynamics models are typically learned offline. This implies that the models often fail to account for the dynamic uncertainties experienced by the system during deployment. Learning the models online is possible, but that typically requires substantial training data and computational resources. As the second contribution of this defense, I alleviate these shortcomings by developing an adaptive framework that boosts both sample and computational efficiency, along with dynamic uncertainty compensation in learning-based MPC. A third challenge of learning-based MPC frameworks, is that there are often little or no guarantees on the accuracy of the data-driven models. As the third contribution of this defense, I leverage recent uncertainty quantification techniques to extract uncertainty estimates for the model predictions, which are equipped with probabilistic guarantees. These estimates are shown to be not overly conservative and are incorporated within a robustification framework to enhance the robustness of the system.

MEAM Seminar: "Can Materials From the 1930’s Really Revolutionize Battery Manufacturing?"
2024-11-19 10:15 - 11:15 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Fluorinated polymers offer a plethora of unique and sometimes perplexing properties. One of the most interesting is the ability for specific types of polytetrafluoroethylene (PTFE) to undergo room-temperature, sheer-induced, structural transformations leading “unwinding” of crystallites and the formation of nano-scale fibers. This process is commonly referred to as “fibrillation”. The material properties required for this deformation mechanism are so unique that no other polymer is known to exhibit this behavior. By utilizing and controlling this property, complex composites can be manufactured with polymer loadings of less than 1% weight. Recently, this methodology has been used to revolutionize both cathode and anode manufacturing for lithium-ion batteries. This talk will overview the fundamentals of fibrillation, show methods to characterize structures, and discuss unique applications for these materials.

ESE Fall Seminar - "Non-Parametric Analysis of Dynamical Systems: From Recurrent Sets to Generalized Lyapunov and Barrier Conditions"
2024-11-19 11:00 - 12:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
This talk presents novel non-parametric methods for analyzing dynamical systems using solely trajectory data. Our critical insight is to replace the notion of invariance, a core concept in Lyapunov Theory, with the more relaxed condition of recurrence. Specifically, a set is τ-recurrent if every trajectory that starts within the set returns to it after at most τ seconds. We leverage this notion of recurrence to develop several analysis tools and algorithms to study dynamical systems. Firstly, we consider the problem of learning an inner approximation of the region of attraction (ROA) of an asymptotically stable equilibrium point using trajectory data. We show that a τ-recurrent set containing a stable equilibrium must be a subset of its ROA under mild assumptions and develop algorithms that compute inner approximations of the ROA using counter-examples of recurrence obtained by sampling finite-length trajectories. Secondly, we generalize Lyapunov and Barrier Function Methods to allow for non-monotonic evolution of the function values by only requiring sub-level sets to be τ-recurrent (instead of invariant). We provide conditions for stability and safety using τ-monotonic functions (functions whose value along trajectories monotonically increases or decreases after at most τ seconds) and develop a verification algorithm that leverages GPU parallel processing power to verify stability and safety using only trajectory information. We finalize by discussing future research directions and possible extensions for control.

CIS Seminar: " Just Infrastructures"
2024-11-19 15:30 - 16:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Sociotechnical systems enable large-scale connection and the dissemination of timely, engaging information. However, these systems are shaped by complex, often invisible governance structures—comprising rules, roles, and relationships—that significantly influence how they operate. Gaining even a basic understanding of these governance structures is key to using them more effectively and deliberately. Yet, many of the millions who depend on these systems are unaware of the governance mechanisms at play or their own degree of autonomy within them. In this talk, I will present methods to uncover hidden governance structures, unveil the illusion of control, and emphasize the importance of amplifying silenced voices to reshape both governance and our relationship with technology and one another — the goal being to create Just Infrastructures.

CIS Seminar: "Just Infrastructures"
2024-11-19 15:30 - 16:30 | Wu & Chen Auditorium
