{"title":"A Trade-Off Between Time and Energy of Stochastic Higher-Order Networks on Multi-Directed Hypergraphs","authors":"Sasa Chen;Dan Liu;Binrui Wang;Jun Mao;Xiaohang Li","doi":"10.1109/LCSYS.2026.3652578","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3652578","url":null,"abstract":"This letter concentrates on the trade-off between control time and energy consumption in achieving finite-time synchronization of stochastic higher-order networks. Different from the existing results that either only consider pairwise interactions between nodes or restrict higher-order interactions to 1-directed hyperedges, multi-directed hypergraphs are employed to better describe group interactions in real networks. A switching control strategy is proposed to estimate the control time and energy consumption in achieving finite-time synchronization of higher-order networks. In addition, to discuss the trade-off between control time and energy consumption, an evaluation index function with adjustable weights is constructed to analyze the optimal control gains in finite time. Finally, an example for higher-order complex networks composed of Chua’s circuits is provided to validate the effectiveness of the proposed results.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"9 ","pages":"3143-3148"},"PeriodicalIF":2.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stochastic Coordinate Descent via Regret Minimization","authors":"Yankai Lin;Xiaopuwen Wang","doi":"10.1109/LCSYS.2026.3653302","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3653302","url":null,"abstract":"In this letter, we investigate the performance of stochastic coordinate descent algorithms for convex optimization problems from the novel perspective of regret minimization. Specifically, we consider a stochastic coordinate selection rule that might vary over time, whereas existing results commonly focus on stochastic selection rules that remain fixed. Moreover, unlike most existing results, which assume that the expectation of algorithm updates follows the exact negative gradient direction, our framework is applicable to any stochastic gradient descent (SGD) like algorithms with estimated gradients that satisfy our main assumption, thus making our approach more general than existing results. We show that the updates of the stochastic algorithm to solve a standard convex optimization problem also serve as an online algorithm for an online convex optimization problem that has time-varying cost functions at each time step. We prove that, under relatively weak assumptions, the online algorithm achieves sublinear regret against the solution of the problem, therefore ensuring the average performance of the algorithm within a finite time window. Finally, we verify our theoretical results by solving a linear regression problem using the proposed algorithm.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"9 ","pages":"3155-3160"},"PeriodicalIF":2.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Closing the Loop Inside Neural Networks: Causality-Guided Layer Adaptation for Fault Recovery Control","authors":"Mahdi Taheri;Soon-Jo Chung;Fred Y. Hadaegh","doi":"10.1109/LCSYS.2026.3652898","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3652898","url":null,"abstract":"This letter studies the problem of real-time fault recovery control for nonlinear control-affine systems subject to actuator loss of effectiveness faults and external disturbances. We develop a two-stage framework that combines causal inference with selective online adaptation to achieve an effective learning-based recovery control method. In the offline phase, we introduce a causal layer attribution technique based on the average causal effect (ACE) to evaluate the relative importance of each layer in a pretrained deep neural network (DNN) controller compensating for faults. This provides a principled approach to select the most causally influential layer for fault recovery control in the sense of ACE, and goes beyond the widely used last-layer adaptation approach. In the online phase, we deploy a Lyapunov-based gradient update to adapt only the ACE-selected layer to circumvent the need for full-network or last-layer only updates. The proposed adaptive controller guarantees uniform ultimate boundedness (UUB) with exponential convergence of the closed-loop system in the presence of actuator faults and external disturbances. Compared to conventional adaptive DNN controllers with full-network adaptation, our methodology has a reduced computational overhead in the online phase. To demonstrate the effectiveness of our proposed methodology, a case study is provided on a 3-axis attitude control system of a spacecraft with four reaction wheels.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"9 ","pages":"3137-3142"},"PeriodicalIF":2.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Encoding High-Level Knowledge in Offline Multi-Agent Reinforcement Learning Using Reward Machines","authors":"Shayan Meshkat Alsadat;Zhe Xu","doi":"10.1109/LCSYS.2026.3651656","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3651656","url":null,"abstract":"Offline reinforcement learning (RL) learns policies from fixed-size datasets without interacting with the environment, while multi-agent reinforcement learning (MARL) faces challenges from large joint state-action spaces and agent interdependencies. Most offline MARL methods apply regularizations, ignoring system-wide dependencies, risking extrapolation errors. We propose Automata-Guided Multi-Agent Offline RL with Reward Machine (AGMORL), a novel framework extending automata learning to offline MARL with reward machines. AGMORL uses a deterministic finite automaton to learn the reward machine from a dataset, capturing team dynamics and agent interactions, while guiding individual policies to avoid out-of-distribution actions by encoding dataset high-level knowledge. Unlike other methods, it avoids secondary components like generative models. We provide convergence guarantees to an optimal policy and show AGMORL outperforms state-of-the-art offline MARL methods.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"9 ","pages":"3149-3154"},"PeriodicalIF":2.0,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cooperative H∞ Consensus Control With Non-Convex Constraints and Parameter Uncertainties","authors":"Hongmei Zhang;Xue Li","doi":"10.1109/LCSYS.2026.3677911","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3677911","url":null,"abstract":"This letter investigates the distributed <inline-formula> <tex-math>$H_{infty }$ </tex-math></inline-formula> consensus problem for an undirected network of first-order and second-order multi-agent systems, under the simultaneous influence of external disturbances, parameter uncertainties, and non-convex control input constraints. To address the nonlinearity caused by the non-convex constraints, a scaling factor approach is employed, enabling the transformation of the original systems into their equivalent reduced-order forms. Based on this transformation, a tailored Lyapunov function is constructed, and sufficient conditions are derived to ensure that all agents achieve consensus with a desired <inline-formula> <tex-math>$H_{infty }$ </tex-math></inline-formula> performance index while satisfying corresponding non-convex input constraints. Finally, a numerical simulation is presented to verify the effectiveness of the proposed theoretical results.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"325-330"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147937425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrés J. Serrano-Balbontín;Inés Tejado;Blas M. Vinagre;Sumeet S. Aphale;Andres San-Millan
{"title":"Spiking Control of a Solenoid Valve for High-Precision Pressure Regulation in Soft Robotics","authors":"Andrés J. Serrano-Balbontín;Inés Tejado;Blas M. Vinagre;Sumeet S. Aphale;Andres San-Millan","doi":"10.1109/LCSYS.2026.3672133","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3672133","url":null,"abstract":"Solenoid valves are widely used for pressure regulation in soft pneumatic robots, yet their intrinsic electromechanical nonlinearities, including dead-zone, saturation, and pressure-dependent dynamics, pose significant challenges for control design. Conventional pulse-modulated strategies, such as pulse-width modulation (PWM), often aggravate these effects by ignoring the transient behaviour associated with valve switching. This work introduces a spiking-based control strategy inspired by neuromorphic principles and specifically tailored for pneumatic pressure regulation in soft actuators. The proposed method uses a neuron-like modulator in cascade with a conventional controller to effectively shape the valve input, intrinsically compensate dead-zone and saturation, and improve the linearity of the pressure dynamics through parameter tuning. A complete experimental validation is conducted on a soft pneumatic actuator (SPA) driven by a solenoid valve, benchmarking the proposed approach against standard pulse-modulation techniques. The results show substantial improvements in both static and dynamic linearity, reduced nonlinear distortions, and enhanced consistency in closed-loop pressure control across operating points.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"127-132"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11426894","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147557647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Robust Direct Data-Driven Ellipsoidal Predictive Control Scheme","authors":"Francesco Giannini;Fabrizio Ranieri","doi":"10.1109/LCSYS.2026.3675270","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3675270","url":null,"abstract":"This paper presents a Direct Data-Driven Control strategy for unknown linear systems subject to process noise. The idea is to customize a set-theoretic receding horizon controller within a data driven setting by properly converting Model-based conditions in terms of data series on the available input and state signals. The main results here are 1) a set of Linear Matrix Inequalities conditions that, by using the available data, allows the computation of the inner ellipsoidal approximation of the predecessor set of a given ellipsoidal set; and 2) a Direct Data-Driven Control scheme - named Robust Ellipsoidal Set-Theoretic Data-Enabled Predictive Control - in charge of controlling the plant by means of the previously computed sets. The resulting control strategy guarantees satisfaction of state and input constraints. Moreover, (a) in absence of process noise, the proposed solution is proven to coincide with the Model-based one; whereas (b) in the presence of noise, the proposed solution computes an inner approximation of the controllability sets able to maintain the required guarantees. Numerical simulations show that the proposed control scheme solves the problem of the constrained regulation to an equilibrium of an unknown plant by means of an informative trajectory without identification of the underlined dynamics, despite any realization of the process noise.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"163-168"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147557782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Decentralized Stubborn Observer Redesign With Exact Outlier Cancellation","authors":"Beatrice Zambotti;Vincent Andrieu;Daniele Astolfi;Laurent Bako;Luca Zaccarian","doi":"10.1109/LCSYS.2026.3699396","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3699396","url":null,"abstract":"We propose a decentralized stubborn observer architecture for linear time-invariant (LTI) systems. Partitioning the outputs into blocks with individual adaptive thresholds isolates measurement corruptions and prevents their propagation. By mapping the system into a lower block-triangular form, we prove global exponential stability (GES) in the disturbance-free case. Moreover, we establish Input-to-State Stability (ISS) to output disturbances and exact cancellation of impulsive outliers under relaxed block-wise dwell-time conditions. Numerical simulations on a vehicle platoon illustrate the improved robustness compared with centralized designs.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"541-546"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-Order CBF-Compatible Semantics and Hierarchical Synthesis for Bounded-Time STL","authors":"Chao Tang;Penghong Lu;Zhenpeng Lao;Gang Chen","doi":"10.1109/LCSYS.2026.3700689","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3700689","url":null,"abstract":"This letter studies bounded-time signal temporal logic (STL) control for nonlinear systems whose output predicates have finite relative degree. We augment the plant with a deterministic bounded-time monitor and derivative-chain coordinates, obtaining a lifted state on which high-order CBF constraints enforce monitor-indexed stay and target tubes. Exactness is not claimed for arbitrary HOCBF sets; it is localized to a certified atomic class in which the lifted barrier-compatible set equals the one-step atomic winning set. For atoms certified in this class and a reset-consistent finite monitor, exactness propagates through Boolean and bounded-time temporal operators. A sampled-data hierarchical HOCBF-QP then minimizes sampled semantic slack before reference tracking. Under strict tube-wise feasibility and an intersample-preservation margin, recursive feasibility and conditional exact satisfaction are established for the certified subclass. A double-integrator study illustrates the online implementation and baseline separation, without using the experiment as a proof of the atomic equality certificate.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"547-552"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Curvature-Aware Expected Free Energy as an Acquisition Function for Bayesian Optimization","authors":"Ajith Anil Meera;Wouter M. Kouw","doi":"10.1109/LCSYS.2026.3708556","DOIUrl":"https://doi.org/10.1109/LCSYS.2026.3708556","url":null,"abstract":"We propose an Expected Free Energy-based acquisition function for Bayesian optimization to solve the joint learning and optimization problem, i.e., optimize and learn the underlying function simultaneously. We show that, under specific assumptions, Expected Free Energy reduces to Upper Confidence Bound, Lower Confidence Bound, and Expected Information Gain. We prove that Expected Free Energy has unbiased convergence guarantees for concave functions. Using the results from these derivations, we introduce a curvature-aware update law for Expected Free Energy and demonstrate it on a system identification problem in a Van der Pol oscillator. On a two-dimensional benchmark with an oscillatory landscape, our adaptive Expected Free Energy acquisition achieves competitive performance in both regret and mean squared error, unlike standard acquisition functions that typically only perform well in one metric.","PeriodicalId":37235,"journal":{"name":"IEEE Control Systems Letters","volume":"10 ","pages":"1693-1698"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148489236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}