soh
Reinforcement Learning for Robust Ageing-Aware Control of Li-ion Battery Systems with Data-Driven Formal Verification
Coppola, Rudi, Touloujian, Hovsep, Ombrini, Pierfrancesco, Mazo, Manuel Jr
Rechargeable lithium-ion (Li-ion) batteries are a ubiquitous element of modern technology. In the last decades, the production and design of such batteries and their adjacent embedded charging and safety protocols, denoted by Battery Management Systems (BMS), has taken central stage. A fundamental challenge to be addressed is the trade-off between the speed of charging and the ageing behavior, resulting in the loss of capacity in the battery cell. We rely on a high-fidelity physics-based battery model and propose an approach to data-driven charging and safety protocol design. Following a Counterexample-Guided Inductive Synthesis scheme, we combine Reinforcement Learning (RL) with recent developments in data-driven formal methods to obtain a hybrid control strategy: RL is used to synthesise the individual controllers, and a data-driven abstraction guides their partitioning into a switched structure, depending on the initial output measurements of the battery. The resulting discrete selection among RL-based controllers, coupled with the continuous battery dynamics, realises a hybrid system. When a design meets the desired criteria, the abstraction provides probabilistic guarantees on the closed-loop performance of the cell.
Real-time monitoring of the SoH of lithium-ion batteries
Jammes, Bruno, Sepúlveda-Oviedo, Edgar Hernando, Alonso, Corinne
Real-time monitoring of the state of health (SoH) of batteries remains a major challenge, particularly in microgrids where operational constraints limit the use of traditional methods. As part of the 4BLife project, we propose an innovative method based on the analysis of a discharge pulse at the end of the charge phase. The parameters of the equivalent electrical model describing the voltage evolution across the battery terminals during this current pulse are then used to estimate the SoH. Based on the experimental data acquired so far, the initial results demonstrate the relevance of the proposed approach. After training using the parameters of two batteries with a capacity degradation of around 85%, we successfully predicted the degradation of two other batteries, cycled down to approximately 90% SoH, with a mean absolute error of around 1% in the worst case, and an explainability score of the estimator close to 0.9. If these performances are confirmed, this method can be easily integrated into battery management systems (BMS) and paves the way for optimized battery management under continuous operation.
Deep learning for state estimation of commercial sodium-ion batteries using partial charging profiles: validation with a multi-temperature ageing dataset
Liu, Jiapeng, Li, Lunte, Xiang, Jing, Xie, Laiyong, Wang, Yuhao, Ciucci, Francesco
Accurately predicting the state of health for sodium-ion batteries is crucial for managing battery modules, playing a vital role in ensuring operational safety. However, highly accurate models available thus far are rare due to a lack of aging data for sodium-ion batteries. In this study, we experimentally collected 53 single cells at four temperatures (0, 25, 35, and 45 {\deg}C), along with two battery modules in the lab. By utilizing the charging profiles, we were able to predict the SOC, capacity, and SOH simultaneously. This was achieved by designing a new framework that integrates the neural ordinary differential equation and 2D convolutional neural networks, using the partial charging profile as input. The charging profile is partitioned into segments, and each segment is fed into the network to output the SOC. For capacity and SOH prediction, we first aggregated the extracted features corresponding to segments from one cycle, after which an embedding block for temperature is concatenated for the final prediction. This novel approach eliminates the issue of multiple outputs for a single target. Our model demonstrated an $R^2$ accuracy of 0.998 for SOC and 0.997 for SOH across single cells at various temperatures. Furthermore, the trained model can be employed to predict single cells at temperatures outside the training set and battery modules with different capacity and current levels. The results presented here highlight the high accuracy of our model and its capability to predict multiple targets simultaneously using a partial charging profile.
Battery State of Health Estimation Using LLM Framework
Yunusoglu, Aybars, Le, Dexter, Tiwari, Karn, Isik, Murat, Dikmen, I. Can
Battery health monitoring is critical for the efficient and reliable operation of electric vehicles (EVs). This study introduces a transformer-based framework for estimating the State of Health (SoH) and predicting the Remaining Useful Life (RUL) of lithium titanate (LTO) battery cells by utilizing both cycle-based and instantaneous discharge data. Testing on eight LTO cells under various cycling conditions over 500 cycles, we demonstrate the impact of charge durations on energy storage trends and apply Differential Voltage Analysis (DVA) to monitor capacity changes (dQ/dV) across voltage ranges. Our LLM model achieves superior performance, with a Mean Absolute Error (MAE) as low as 0.87\% and varied latency metrics that support efficient processing, demonstrating its strong potential for real-time integration into EVs. The framework effectively identifies early signs of degradation through anomaly detection in high-resolution data, facilitating predictive maintenance to prevent sudden battery failures and enhance energy efficiency.
Fast State-of-Health Estimation Method for Lithium-ion Battery using Sparse Identification of Nonlinear Dynamics
Lee, Jayden Dongwoo, Seo, Donghoon, Shin, Jongho, Bang, Hyochoong
Lithium-ion batteries (LIBs) are utilized as a major energy source in various fields because of their high energy density and long lifespan. During repeated charging and discharging, the degradation of LIBs, which reduces their maximum power output and operating time, is a pivotal issue. This degradation can affect not only battery performance but also safety of the system. Therefore, it is essential to accurately estimate the state-of-health (SOH) of the battery in real time. To address this problem, we propose a fast SOH estimation method that utilizes the sparse model identification algorithm (SINDy) for nonlinear dynamics. SINDy can discover the governing equations of target systems with low data assuming that few functions have the dominant characteristic of the system. To decide the state of degradation model, correlation analysis is suggested. Using SINDy and correlation analysis, we can obtain the data-driven SOH model to improve the interpretability of the system. To validate the feasibility of the proposed method, the estimation performance of the SOH and the computation time are evaluated by comparing it with various machine learning algorithms.
Enhanced Gaussian Process Dynamical Models with Knowledge Transfer for Long-term Battery Degradation Forecasting
Xing, Wei W., Zhang, Ziyang, Shah, Akeel A.
Predicting the end-of-life or remaining useful life of batteries in electric vehicles is a critical and challenging problem, predominantly approached in recent years using machine learning to predict the evolution of the state-of-health during repeated cycling. To improve the accuracy of predictive estimates, especially early in the battery lifetime, a number of algorithms have incorporated features that are available from data collected by battery management systems. Unless multiple battery data sets are used for a direct prediction of the end-of-life, which is useful for ball-park estimates, such an approach is infeasible since the features are not known for future cycles. In this paper, we develop a highly-accurate method that can overcome this limitation, by using a modified Gaussian process dynamical model (GPDM). We introduce a kernelised version of GPDM for a more expressive covariance structure between both the observable and latent coordinates. We combine the approach with transfer learning to track the future state-of-health up to end-of-life. The method can incorporate features as different physical observables, without requiring their values beyond the time up to which data is available. Transfer learning is used to improve learning of the hyperparameters using data from similar batteries. The accuracy and superiority of the approach over modern benchmarks algorithms including a Gaussian process model and deep convolutional and recurrent networks are demonstrated on three data sets, particularly at the early stages of the battery lifetime.
Evaluating feasibility of batteries for second-life applications using machine learning
Takahashi, Aki, Allam, Anirudh, Onori, Simona
This paper presents a combination of machine learning techniques to enable prompt evaluation of retired electric vehicle batteries as to either retain those batteries for a second-life application and extend their operation beyond the original and first intent or send them to recycle facilities. The proposed algorithm generates features from available battery current and voltage measurements with simple statistics, selects and ranks the features using correlation analysis, and employs Gaussian Process Regression enhanced with bagging. This approach is validated over publicly available aging datasets of more than 200 cells with slow and fast charging, with different cathode chemistries, and for diverse operating conditions. Promising results are observed based on multiple training-test partitions, wherein the mean of Root Mean Squared Percent Error and Mean Percent Error performance errors are found to be less than 1.48% and 1.29%, respectively, in the worst-case scenarios.
Researchers use neuromorphic chips and electronic 'skin' to give robots a sense of touch
We take our sense of touch for granted. Simple tasks like opening a jar or tying our shoelaces would be a whole lot more complex if we couldn't feel the object with our hands. Robots typically struggle to replicate this sense, restricting their ability to manipulate objects. But researchers from the National University of Singapore (NUS) might have found a solution: pairing artificial skin with a neuromorphic "brain." The system was developed by a team led by Assistant Professors Benjamin Tee, an electronic skin expert, and Harold Soh, an AI specialist.
Interview: Artificial Intelligence: Thinking Outside the Box (Part One)
Artificial intelligence (AI) is no longer the stuff of science fiction. While robot maids may not yet be a reality, researchers are working hard to create reasoning, problem-solving machines whose "brains" might rival our own. Seán Ó hÉigeartaigh (anglicized as Sean O'Hegarty), while enthusiastic about the benefits that AI can bring, is also wary of the technology's dark side. He holds a doctorate in genomics from Trinity College Dublin and is now executive director of the Center for the Study of Existential Risk at the University of Cambridge. He has played a central role in international research on the long-term impacts and risks of AI.
Nebraska researchers partner with Library of Congress
How can the United States Library of Congress -- one of the world's largest repositories of information -- bring its collections into the digital age? It's a question library leadership has been attempting to answer, and a collaboration between the Library of Congress and University of Nebraska–Lincoln scholars and students has laid a strong foundation for machine learning to play a role in future digital strategies. In 2018, the Digital Strategy Division of the Library of Congress released a five-year digital strategy for the library, with a goal of maximizing the value of its collections for research. As part of that strategy, the library began seeking a collaboration to test machine learning across different materials, since the library's collections are so varied. The Aida digital libraries research lab, led by Husker researchers Elizabeth Lorang, associate professor in University Libraries, and Leen-Kiat Soh, professor of computer science and engineering, were awarded a research services contract following a call for proposals from the library.