DEI Talks | “Accelerating Implicit Mechanics” by Robert F. Lucas

“Historically, the run time of implicit mechanics has been dominated by the time required to solve a large sparse linear system. The default solver is a multifrontal sparse matrix factorization, which will reliably solve ill conditioned, indefinite problems. The multifrontal method turns a sparse matrix factorization into a directed acyclic graph of smaller, dense “frontal” matrix factorizations, and these can be accelerated using Graphics Processing Units. As the number of processors used grows into the thousands, reordering the sparse matrix to reduce the storage and operations required to factor it, is the emerging computational bottleneck. Reordering is NP-complete, and in computational mechanics the preferred heuristic is nested dissection, i.e., recursive graph partitioning. Finding a balanced min cut is NP-hard, and classical codes such as ParMetis have limited parallel scaling. This talk will also discuss on-going work to explore a new generation of specialized devices for solving optimization problems. These include the D-Wave adiabatic quantum annealer, so called Silicon annealers produced by Fujitsu and Toshiba, the LightSolver Laser Processing Unit. The Digital Annealer is a dedicated chip that uses non-von Neumann architecture to minimize data movement in solving combinatorial optimization problems.”

“Accelerating Implicit Mechanics” will be presented October 10, at 15:00, room Vasco Sá (L119) – Sala de Atos do Departamento de Engenharia Mecânica.

“Dr. Robert F. Lucas received his BSc, MSc, and PhD degrees in Electrical Engineering from Stanford University in 1980, 1983, and 1988 respectively. He is currently an Ansys Fellow where he is responsible for the default multifrontal linear solver used in LS-DYNA and MAPDL. Previously, he was the Operational Director of the University of Southern California (USC) – Lockheed Martin Quantum Computing Center. Before joining USC, he was the Head of the High-Performance Computing Research Department in the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory and before that the Deputy Director of DARPA’s Information Technology Office. From 1988 to 1998 he was a member of the research staff of the Institute for Defense Analyses’s Center for Computing Sciences. From 1979 to 1984 he was a member of the Technical Staff of the Hughes Aircraft Company.”

Note: This talk is preceded by another talk, geared towards Mechanical Engineering and focusing on the use of ANSYS/LS-DYNA for modeling and simulation, by the same speaker at 14:00, in the same room, entitled “An Industrial Grand Challenge”. You are all welcome.

PhD Defense in Informatics Engineering: ”Enhanced multiview experiences through remote content selection and dynamic quality adaptation”

Candidate
Tiago André Queiroz Soares da Costa

Date, Time and Location:
September 16, 14:30, Sala de Atos da Faculdade de Engenharia da Universidade do Porto

President of the Jury:
Doutor Carlos Miguel Ferraz Baquero-Moreno, Professor Catedrático da Faculdade de Engenharia da Universidade do Porto

Members:
Klara Nahrstedt, PhD, Full Professor, Department of Computer Science, University of Illinois at Urbana-Champaign, United States of America;
Pedro António Amado de Assunção, PhD, Coordinator Professor, Departamento de Engenharia Eletrotécnica, Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Leiria;
Luís António Pereira de Meneses Corte-Real, PhD, Associate Professor, Departamento de Engenharia Eletrotécnica e de Computadores, Faculdade de Engenharia da Universidade do Porto;
Maria Teresa Magalhães da Silva Pinto de Andrade, PhD, Assistant Professor, Departamento de Engenharia Eletrotécnica e de Computadores, Faculdade de Engenharia da Universidade do Porto (Supervisor).

Abstract:
This thesis proposes a novel approach to immersive, multiview media distribution that uses Deep Learning models and user-centric data to predict user interest in the near future while multimediacontent is being presented. The main objective of this thesis is to give the user a truly ubiquitousmultimedia immersive experience without the need for expensive equipment, while also allowing him or her to see the scene being presented on the screen from almost any angle, as if they were actually there when the scene was shot. A methodological approach was envisioned based on the literature review and the identification of gaps in immersive streaming scenarios, which resulted in the conceptualization of a brand new architecture that was coined Smooth Multiview (SmoothMV). This architecture is capable of analysing user behaviour data in real-time and preemptively preparing content delivery accordingly based on viewing interests demonstrated by users while visualising a particular scene. Users effortlessly provide behaviour data without equiring intrusive equipment, which is then processed using the novel concept of the Hot&Cold matrix, which this thesis describes. With the use of this concept, the screen is divided into nine separate regions, each of which is connected to a neighbouring view that the SmoothMV architecture can prepare and choose to present. Separate queues designated for playback and buffering of upcoming content segments are introduced to provide minimal delay without compromising the user experience, since content adaptation is closely linked to user inputs. The number of views that are available and the approach employed for analysing behaviour while viewing content and selecting which view should be processed in the following moment affect how these queues are managed. This thesis developed from a purely reactive approach to a sophisticated, twofold Deep Learning architecture that can accurately identify the view that best fits the interests of the user with a high degree of accuracy. The development of a new dataset was needed in order to achieve this level of performance, as the data provided by existing datasets was not suitable for the scenario that was proposed. After a series of 128 experiments were conducted to collect visual attention data from 45 participants while viewing multi-perspective content, the Data2MV dataset was created and made available to the public. This thesis’ fundamental concepts and practical outputs are considered to be of significant importance to the body of knowledge currently available in the field of research, while also offering relevant tools for the general enhancement of current content distribution architectures.

Keywords: Multimedia, Streaming, Multiview, Focus-of-Attention, Deep Learning

DEI Talks | The Limitations of Data, Machine Learning & Us by Prof. Ricardo Baeza-Yates

“Machine learning (ML), particularly deep learning, is being used everywhere. However, not always is used well, ethically and scientifically. In this talk we first do a deep dive in the limitations of supervised ML and data, its key component. We cover small data, datification, bias, predictive optimization issues, evaluating success instead of harm, and pseudoscience, among other problems.  The last part is about our own limitations using ML, including different types of human incompetence: cognitive biases, unethical applications, no administrative competence, copyright violations, misinformation, and the impact on mental health. In the final part we discuss regulation on the use of AI and responsible AI principles, that can mitigate the problems outlined above.”

The Limitations of Data, Machine Learning & Us” will be presented September 10, at 11:00, room B032. Free entry but registration required here.

Ricardo Baeza-Yates is the Director of Research at the Institute for Experiential AI of Northeastern University, as well as part-time professor at the Dept. of Computer Science of University of Chile. Before, he was VP of Research at Yahoo Labs, based in Barcelona, Spain, and later in Sunnyvale, California, from 2006 to 2016. He is co-author of the best-seller Modern Information Retrieval textbook published by Addison-Wesley in 1999 and 2011 (2nd ed), that won the ASIST 2012 Book of the Year award. From 2002 to 2004 he was elected to the Board of Governors of the IEEE Computer Society and between 2012 and 2016 was elected for the ACM Council. In 2009 he was named ACM Fellow and in 2011 IEEE Fellow, among other awards and distinctions. He obtained a Ph.D. in CS from the University of Waterloo, Canada, and his areas of expertise are responsible AI, web search and data mining plus data science and algorithms in general.”

Applications for the Prof. Doutor Raul Vidal/Deloitte Prize are now open

The period for submitting applications for the Prof. Doutor Raul Vidal/Deloitte Prize has been running since July 19th. Students from the Master in Informatics and Computing Engineering and the Master in Software Engineering can apply until August 31st for the prize which is now in its third edition.

This award is intended to honour a recent graduate from one of these FEUP courses who has distinguished themselves in curricular activities, for the quality and innovation of the work carried out within the scope of Software Engineering, for their involvement in activities to support other students, namely in activities associated with FEUP’s student groups, and also for their involvement in social and solidarity initiatives.

The award was proposed by Deloitte, with the support of FEUP, through DEI, with the aim of honouring the Professor Emeritus of U.Porto in recognition of all his work at FEUP in the area of Informatics Engineering which has resulted in FEUP’s projection at national and international level and in the high-quality preparation of its students for the labour market, making FEUP unquestionably one of the leading schools with excellent technological teaching.

All the information on the application process and regulation can be found at: Prémio Prof. Doutor Raul Vidal – DEI – Departamento de Engenharia Informática (up.pt)

FC Portugal the big winner at RoboCUP 2024

The Genneper Parken in Eindhoven hosted the 2024 edition of RoboCUP, the most exciting event in the world of autonomous robots. The joint team from the Universities of Porto and Aveiro, FC Portugal, was crowned Robotic Simulated Football champion for the third time in this competition. The final against the German team MagmaOffenburg saw FC Portugal win 5-3, a result that underlines the quality of the highly effective and cohesive Portuguese team.

A team of finalists from the L:IACD – Degree in Artificial Intelligence and Data Science, a joint course between the Faculties of Sciences (FCUP) and Engineering (FEUP) of the University of Porto, contributed to this victory. Tomás Azevedo and Francisco Gomes da Silva were present at this final of the 3D Simulation League – Humanoids.

Their victory at RoboCup 2024 is the result of Machine Learning (ML) and Deep Reinforcement Learning (DRL) methodologies used to train robotic agents, which are part of the themes covered at L:IACD. ML allows robots to learn and improve their performance based on data and previous experiences, while DRL focuses on teaching robots to make optimal decisions through interaction with the simulation environment.

In the context of the 3D Simulation League, these techniques were essential for developing agents capable of performing complex tasks such as team coordination, game strategy, advanced individual skills (such as shooting, sprinting and dribbling). The FC Portugal robots were trained to learn autonomously and optimise their behaviour on an ongoing basis, resulting in a winning team, which also won the Scientific Challenge (best innovative contribution to the progress of this league) and the ‘FatProxy’ Challenge (simulation of humanoids using high-level ‘move’ and ‘kick’ commands instead of direct control of the various degrees of freedom).

The team’s success is evidenced by the 30 international awards achieved and the publication of more than 100 scientific articles in indexed journals and conferences.

Brasil will be the next destination of RoboCUP which will bring the world’s competition enthusiasts to Salvador from 15 to 21 July 2025.

All the information at: https://2024.robocup.org/

Photo: Bart van Overbeeke

PhD Defense in Digital Media: “Narrative in Interactive Documentary: a Categorisation Framework”

Candidate
Ana Sofia Airosa Coelho de Passos Baptista

Date, Time and Location
July 23, 4:30, Sala de Atos FEUP

President of the Jury
António Fernando Vasconcelos Cunha Castro Coelho (PhD), Associate Professor with Habilitation, Departamento de Engenharia Informática, Faculdade de Engenharia da Universidade do Porto.

Members
Paulo Filipe Gouveia Monteiro (PhD), Full Professor, Departamento de Ciências da Comunicação, Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa;
Manuela Maria Fernandes Penafria (PhD), Associate Professor, Departamento de Artes da Faculdade de Artes e Letras, Universidade da Beira Interior;
Patrícia Nogueira da Silva (PhD), Assistant Professor, Departamento de Artes da Faculdade de Artes e Letras, Universidade da Beira Interior;
José Manuel Pereira Azevedo (PhD), Full Professor, Departamento de Ciências da Comunicação e da Informação, Faculdade de Letras, Universidade do Porto (Supervisor);
Hugo Daniel da Silva Barreira (PhD), Assistant Professor, Departamento de Ciências e Técnicas do Património, Faculdade de Letras, Universidade do Porto.

Abstract
Interactive Documentary offers innovative ways of telling reality-based stories, it reaches wider audiences more easily, and its availability, granted by the internet, seems durable. Nevertheless, we soon realised that their many possibilities came with as many obstacles. In addition to an even trickier production system, involving professionals with technological skills, a revenue model adapted to the web distribution, and the problem of technological obsolescence, interactive storytelling is a complex challenge. The openness inherent to interactivity affects how the story is constructed and experienced by the audience. Some interactive documentaries focus more on navigation rather than on the story. Narrative and storytelling are often neglected in research, as it tends to focus on the new affordances of interactivity. This journey aimed at understanding how interactive documentaries can balance the need for meaningful coherent stories with the advantage of interactivity and potential non-linearity and collaboration, through new narrative structures. We aim to support creators and researchers in the development and study of interactive documentaries, by identifying strategies and best practices regarding narrative and storytelling, based on literature review, case studies and interviews. For practical application, we propose a Categorisation Framework, illustrated with the case studies, which allows us to typify i-docs from the perspective of narrative and storytelling. Finally, we suggest a hands-on guide, comprising twelve tactics, for creators who aim to develop interactive documentaries with more meaningful and coherent narratives.

Keywords: Interactive Documentary; Narrative; Storytelling; Interactivity; Linearity; Categorisation.

PhD Defense in Digital Media (PDMD): ”Emotion-driven Physiological Actor Dynamics For Interactive Theatre Sound”

Candidate
Luís Alberto Teixeira Aly

Date, Time and Location
July 22, 14:00, Sala de Atos, FEUP

President of the Jury
António Fernando Vasconcelos Cunha Castro Coelho (PhD), Associate Professor with Habilitation, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto.

Members
Javier Enrique Jaimovich Fernández (PhD), Associate Professor, Departamento de Sonido da Facultad de Artes, Universidad de Chile, Chile;
William Ruddock Primett (PhD), Postdoctoral Researcher, School of Digital Technologies, Tallinn University, Estónia;
Carla Maria de Jesus Montez Fernandes (PhD), Main Researcher, Instituto de Comunicação (ICNOVA), Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa;
Rui Pedro Amaral Rodrigues (PhD), Associate Professor, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto;
Gilberto Bernardes de Almeida (PhD), Assistant Professor, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto (Supervisor).

The thesis was co-supervised by Hugo Plácido da Silva (PhD), from Instituto Superior Técnico.

Abstract

This thesis, titled ’Emotion-driven Physiological Actor Dynamics For Interactive Theatre Sound,’ embarks on an exploratory journey into the innovative integration of physiological responses with emotional expression and sound design within theatre. This research investigates the intricate relationship between actors’ emotional states and physiological signals, delves into the impact of sound generated from physiological data on the actors’ emotional expression and agency, and examines how this novel integration can redefine traditional theatrical narratives and storytelling techniques. The study examines actors’ experiences and perceptions using qualitative and quantitative methodologies. It utilizes focus groups, observational studies, and sophisticated physiological sensors and surveys to capture and analyze the physiological signals and the feedback from actors. This approach allows for a nuanced understanding of the interplay between the physiological and emotional aspects of acting, shedding light on how actors embody and convey complex emotions through their performances. A key empirical contribution of this research is the DECEIVER dataset, which comprises extensive physiological recordings. These recordings provide valuable insights into the consistency and variability of emotional expression in performance settings. This dataset is a treasure trove for researchers and practitioners in the field, offering unprecedented detail and depth in understanding the physiological underpinnings of theatrical performance. Furthermore, the thesis presents a comprehensive historical analysis of the use of physiological sensors in interactive music, spanning the period from 1965 to 2023. This historical overview not only charts the technological evolution in this domain but also sets the stage for understanding the current trends and potential future developments. It contextualizes the research within the broader trajectory of technological advancements, highlighting the incremental and sometimes revolutionary changes that have shaped the current state of interactive music systems. The thesis introduces an empirical and functional taxonomy for Interactive Music Systems driven by physiological signals. This taxonomy represents a significant contribution to designing and applying physiological signals to interactive musical systems, providing a structured framework that can guide future developments in the field. It categorizes different approaches and methodologies in integrating physiological data into sound design, offering a comprehensive understanding of the potential and limitations of these systems. The research also involves the development of an extensive experimental protocol designed to analyze the physiological correlates of emotional valence and arousal in acting. A sophisticated software toolbox for data processing complements this protocol. The protocol’s design underscores the effectiveness of mental imagery in eliciting specific emotional states and highlights the complexity of emotional expression in theatre actors. This aspect of the research provides a methodological blueprint for future studies aiming to explore similar themes and questions. The Biosignal Processing Toolbox, a software tool for real-time operations integrating physiological signals with sound, is central to the study. The Biosignal Processing Toolbox enables the creation of dynamic, responsive soundscapes that interact with actors, enhancing the storytelling and engagement of the audience in the theatre. The toolbox is equipped to handle various physiological signals such as electromyography, electrocardiography, and electrodermal activity, each offering unique opportunities and challenges for sonification. The versatility of BarT lies in its ability to adapt and respond to different physiological inputs, making it an effective tool for sound designers in the theatre. A significant part of the research was a collaborative techno-artistic project, which utilized Samuel Beckett’s theatre as a backdrop. This project led to developing a prototype for an Interactive Music System driven by physiological sensors. This project explored the transformative possibilities of integrating physiological sensors and gesture typologies into theatre, providing fresh perspectives on character development and narrative construction. The project demonstrated the potential of this technology to bring a new dimension to theatrical performances, allowing for a more immersive and interactive experience for both actors and audiences. Despite its groundbreaking nature, the research acknowledges the challenges and limitations of such technological integrations. These include issues such as the need for real-time data processing, the necessity of actor-specific system calibration, technical and financial constraints, training requirements for actors and production teams, ensuring the comfort and unobtrusiveness of sensors during performances, ethical considerations related to the use of physiological data, and the subjective interpretation of such data in artistic contexts. In conclusion, this thesis contributes to theatre and interactive media art. Exploring the integration of physiological sensors in theatre sound design opens up new avenues for artistic expression and audience engagement. The development of the Biosignal Processing Toolbox and the DECEIVER dataset represent significant advancements in the field, paving the way for more immersive, interactive, and expressive forms of storytelling. This research provides novel perspectives for sound design and actor training and contributes to the broader discourse on the intersection of technology and art.

PhD Defense in Informatics Engineering (ProDEI): ”Time-To-Event Prediction”

Candidate
Maria José Gomes Pedroto

Date, Time and Location
July 22, 10:00, Sala de Atos of FEUP

President of the Jury
Carlos Miguel Ferraz Baquero-Moreno (PhD), Full Professor, Faculdade de Engenharia, Universidade do Porto

Members
Myra Spiliopoulou (PhD), Full Professor of Business Information Systems da Faculty of Computer Science da Otto-von-Guericke-University Magdeburg, Alemanha;
Manuel Filipe Vieira Torres dos Santos (PhD), Associate Professor with Habilitation, Department of Information Systems, Escola de Engenharia, Universidade do Minho;
Alípio Mário Guedes Jorge (PhD), Full Professor, Department of Computer Science, Faculdade de Ciências, Universidade do Porto (Supervisor);
Rui Carlos Camacho de Sousa Ferreira da Silva (PhD), Associate Professor, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto.

The thesis was co-supervised by João Pedro Carvalho Leal Mendes Moreira (PhD), Associate Professor in the Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto.

Abstract

This work is centered on modeling and predicting Time-to-Event (TTE) episodes, and has two distinct purposes. The first purpose is to explore the usage of genealogical data for time to event prediction. Additionally, this work aims to aid medical professionals in improving the diagnosis and prognosis of patients afflicted with Hereditary Transthyretin Amyloidosis (ATTRv amyloidosis). This is a genetic disease with a strong historical background in the fishing villages of Póvoa do Varzim, northern Portugal. In order to explore the value of genealogical data for time-to-event prediction, this work has contributions in feature engineering, namely within the area of feature construction and selection. To this end, it explores and compares a summarizing approach focused on manually extracting meaningful features from genealogical trees with a more automated one using embeddings. It contributes to model construction by creating a multivariate data-oriented approach that tracks a patient’s risk of developing disease onset through different ages. It also explores the impact of combining different age models of neighboring time windows. Finally, it contributes to model evaluation by addressing the implementation issues of a business based

approach to evaluate the expected return of changing clinical guidelines. It also presents robust evaluation schemas that assist the multivariate data-oriented approach in selecting the best model. The application is focused on patients with ATTRv Amyloidosis. To present and characterize the work done, this thesis is structured into four main sections. It begins with an introduction and a presentation of ATTRv Amyloidosis from a medically historic perspective. Then it presents the relevant background by dwelling into the connection of time to event prediction with feature engineering, model construction and model evaluation, as well as introducing key concepts of genealogical studies. After this, it presents its technical contributions, in the form of the main publications that constitute this work (one paper by chapter). It ends with an epilogue section which overviews the work performed, shares the main conclusions, and, finally, discusses the thesis from a technical and clinical perspective.

Keywords: Time-to-Event Data; Data Modeling; Regression Models

DEI TALKS | “Temporal mining on systematically sparse medical data” by Myra Spiliopoulou

“The acquisition of features for patient diagnostics, treatment planing and monitoring purposes is costly. Moreover, when patients with chronic diseases are called to used mobile health apps, they are also called to interact with the app in a regular way; the willingness to do so may wane with time. In this talk, we see forms of missingness in data collected in a clinic for treatment planning and in data collected with an app for monitoring. Then, we discuss methods that iteratively build up a minimal feature subspace for treatment outcome prediction, and neighbourhood-based methods that build up a minimal data space for patient condition monitoring. The methods have been applied on clinical data of tinnitus patients and on mhealth data of patients with tinnitus or diabetes. The results demonstrate that small subsets of features are often adequate for prediction.”

Temporal mining on systematically sparse medical data” will be presented July 22, 15:30, room B012. The talk will be moderated by João Moreira (DEI).

Myra Spiliopoulou is Professor of Business Information Systems at the Faculty of Computer Science, Otto-von-Guericke-University Magdeburg, Germany. Her main research is on mining temporal complex data and extracting predictive patterns from evolving objects. One of the core application areas for her research, and a constant source of inspiration is health: her work encompasses methods and findings from observational medical data, from clinical studies, from digital health solutions, and from experiments on understanding the process of human and animal learning. She is involved as (senior) reviewer in major conferences on data mining and knowledge discovery, as Action Editor in the Data Mining and Knowledge Discovery Journal of Springer Nature, as Special Editor for survey papers in the International Journal of Data Science and Analytics (JDSA) and as Editorial Board Member for the Artificial Intelligence in Medicine Journal. In 2016, 2019 and 2023, she served as a PC Chair of the IEEE Int. Symposium on Computer-Based Medical Systems (CBMS). In 2024, she serves as senior reviewer for KDD 2024. She also serves as one of the Journal Track Chairs for ECML PKDD 2024, responsible for the submissions to the Machine Learning Journal. In May 2023, she received the Distinguished Service Contributions Award for the Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD).

PhD Defense in Informatics Engineering: ”Symmetry, hierarchical structures and shallow neural networks: Advancing reinforcement learning for humanoids”

Candidate:
Miguel António Mourão de Abreu

Date, Time and Location
July 19, 15:00, room Professor Joaquim Sarmento (G129), DEC, Faculdade de Engenharia da Universidade do Porto

President of the Jury:
Rui Filipe Lima Maranhão de Abreu, PhD, Full Professor, Faculdade de Engenharia, Universidade do Porto

Members:
Francisco António Chaves Saraiva de Melo, PhD, Associate Professor with Habilitation, Department of Computer Science and Engineering, Instituto Superior Técnico, Universidade de Lisboa;
Carlos Fernando da Silva Ramos, PhD, Full Professor, Department of Informatics Engineering, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto;
Abbas Abdolmaleki, PhD, Senior Scientist at Google DeepMind;
Luís Paulo Gonçalves dos Reis, PhD, Associate Professor with Habilitation, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto (Supervisor);
Henrique Daniel de Avelar Lopes Cardoso, PhD, Associate Professor, Department of Informatics Engineering, Faculdade de Engenharia, Universidade do Porto;
Armando Jorge Miranda de Sousa, PhD, Associate Professor, Department of Electrical and Computer Engineering, Faculdade de Engenharia, Universidade do Porto.

The thesis was co-supervised by José Nuno Panelas Nunes Lau, PhD, Associate Professor in the Department of Electronics, Telecommunications and Informatics at the Universidade de Aveiro.

Abstract:
In the rapidly evolving field of robotics, reinforcement learning (RL) has become an essential tool. However, as tasks become more complex, traditional RL methods face challenges in terms of sample efficiency, inter-task coordination, stability, and overall solution quality. To address this problem, we investigated various strategies. Initially, we explored ways of enriching the state space while learning skills from scratch with RL, resulting in excellent individual behaviors. However, integrating these behaviors proved challenging, as they often explored the vast action space in a non-structured manner. To address this, we shifted to a structured approach, starting by abstracting the robot’s locomotion model with an analytical controller, and improving the upper body efficiency.
Gradually, the learning component was extended to the entire robot, making the analytical controller a starting point in the learning process, rather than a restriction. We studied realistic external perturbations and ways of leveraging the robot’s symmetry to speed up the optimization. This led to an extension to PPO’s objective function called Proximal Symmetry Loss, with which we created
a fully functional omnidirectional walk with push-recovery abilities. Building on this knowledge, we devised a new symmetry-enriched learning framework based on Skill-Set-Primitives — a novel hierarchical structure that captures commonalities across different skills, easing transitions. This framework simplified the policy into a shallow neural network, significantly improving sample efficiency and stability. Applying this framework, we completely redesigned our simulated soccer team, achieving cohesive high-quality behaviors that secured victory in the RoboCup World Championship in 2022 and 2023. This team included a new localization algorithm with unprecedented accuracy, custom algorithms for path planning, role management, teammate communication, and more. We released the codebase to the RoboCup community, offering a robust Python foundation for new teams. Our work received recognition in scientific challenges, earning awards for introducing
he league’s first running skill, pioneering an agile close control dribble, and developing the most accurate localization algorithm. The contributions extend beyond RoboCup with Adaptive Symmetry Learning, a method of leveraging symmetry  to improve sample efficiency, even in robots not perfectly symmetric by design or those with asymmetrical flaws. A natural next step is to assess how this approach could benefit real humanoid robots, which inherently have imperfections.

Keywords: Reinforcement Learning; Humanoid Robots; Symmetry; Locomotion; Skill-Set-Primitives; Hierarchical Structures; Shallow Neural Networks; RoboCup; Robotic Soccer.