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Search Results (165)

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24 pages, 5556 KB  
Article
MVO: A Magneto-Visual Odometry System for Indoor Positioning
by Tongxing Peng, Chao Ming, Zhengpeng Yang, Huaiyan Wang, Jiyan Yu and Xiaoming Wang
Sensors 2026, 26(14), 4555; https://doi.org/10.3390/s26144555 (registering DOI) - 17 Jul 2026
Abstract
High-precision and resilient indoor positioning is a fundamental requirement for the autonomous operation of mobile robots in GNSS-denied environments. While visual sensors are commonly used for odometry, their operational reliability can be compromised in challenging scenarios such as drastic illumination fluctuations and sparse-textured [...] Read more.
High-precision and resilient indoor positioning is a fundamental requirement for the autonomous operation of mobile robots in GNSS-denied environments. While visual sensors are commonly used for odometry, their operational reliability can be compromised in challenging scenarios such as drastic illumination fluctuations and sparse-textured environments. To address these sensor limitations, this study presents MVO, a magneto-visual odometry framework that explores indoor magnetic field anomalies as complementary constraints for visual odometry. By integrating a 30-magnetometer planar array model with a stereo camera, the proposed system establishes a multi-modal perception framework for indoor spaces. In the frontend, magnetic field gradient information is utilized to provide relative-pose constraints, which assist in the matching of image feature points and help maintain tracking continuity under visual degradation. In the backend, a factor graph optimization (FGO) framework incorporates magnetic relative-pose factors and visual reprojection factors into a unified optimization objective, which is then solved using the incremental smoothing and mapping 2 (iSAM2) algorithm. Frontend-level simulations are conducted to analyze the effects of magnetometer spatial configuration, sensor number, and calibration-error sensitivity on magnetic relative-pose estimation and covariance. Trajectory-level evaluations are further performed on the EuRoC dataset augmented with high-fidelity synthesized magnetic field data, including localization accuracy and computational load. Under this synthesized magnetic field setting, MVO shows improved localization accuracy and moderate computational load compared with the selected MSCKF-Stereo and VINS-Fusion reference baselines. These results provide a simulation-based feasibility validation of integrating magnetic field constraints with visual information for indoor odometry, while validation with real magnetometer array measurements remains future work. Full article
(This article belongs to the Special Issue Intelligent Sensing for Robotic Control and Visual Perception)
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33 pages, 10937 KB  
Article
A Robotic Drilling System with GFTMPC-Based Flexible Control for Small-Diameter Deep Holes in Tire Molds
by Yunhao Zhao, Haining Liu, Bin Wang, Fajia Li and Huanyong Cui
Actuators 2026, 15(6), 291; https://doi.org/10.3390/act15060291 - 26 May 2026
Viewed by 513
Abstract
Vent holes in tire molds typically exhibit large depth-to-diameter ratios (25–50) and variable drilling angles, both of which increase the risk of drill-bit breakage during automated drilling. To address this problem, this study develops a robotic drilling system consisting of a 6-DOF industrial [...] Read more.
Vent holes in tire molds typically exhibit large depth-to-diameter ratios (25–50) and variable drilling angles, both of which increase the risk of drill-bit breakage during automated drilling. To address this problem, this study develops a robotic drilling system consisting of a 6-DOF industrial robot and a dedicated end effector integrating a spindle unit, a linear feed unit, and a telescopic drill-bushing unit. A GRU-based feed-torque model predictive control method (GFTMPC) is proposed for robotic small-diameter deep-hole drilling, which achieves flexible control by integrating angle-aware feed-torque modeling with constrained MPC-based feed-rate optimization. The resulting GRU-based feed-torque model (GFTM) is embedded in the MPC framework for torque prediction and achieves an R2 value of 0.9682. Under identical simulation conditions, GFTMPC reduces the RMSE of the feed-rate increment by 34.82% and the saturation ratio of the feed-rate increment by 90.78% relative to a PID baseline, indicating smoother feed regulation and fewer abrupt control actions in simulation. Comparative engineering experiments further suggest that, under the tested robotic configurations, adaptive feed-rate regulation by GFTMPC is an important contributor to improved tool life and drilling reliability. Hole-diameter measurements show deviations ranging from +0.03 mm to +0.11 mm, which were considered acceptable for the subsequent work steps in this application. Engineering application results show that robotic drilling increases daily throughput per worker by 71.38% and the average number of holes drilled per bit by 237%. Full article
(This article belongs to the Section Actuators for Robotics)
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56 pages, 15179 KB  
Article
Smart Exploration of Lentic Cyanobacterial Water Bodies Supported by Model-Based Simulation, Autonomous Surface Vehicles and Evolutionary Algorithms
by Gonzalo Carazo-Barbero, Eva Besada-Portas, José Antonio López-Orozco and José Luis Risco-Martín
Mathematics 2026, 14(11), 1821; https://doi.org/10.3390/math14111821 - 24 May 2026
Viewed by 241
Abstract
Cyanobacterial blooms in lakes and reservoirs pose significant environmental and public health risks. This paper presents an effective exploration strategy to detect them from Autonomous Surface Vehicles (ASVs) equipped with probes, whose sensing trajectories are optimized by an AI-based planner that considers the [...] Read more.
Cyanobacterial blooms in lakes and reservoirs pose significant environmental and public health risks. This paper presents an effective exploration strategy to detect them from Autonomous Surface Vehicles (ASVs) equipped with probes, whose sensing trajectories are optimized by an AI-based planner that considers the 3D spatial-temporal evolution of the cyanobacteria concentration obtained by a multiphysics model. The planner, simultaneously working on the AI decision-making and robotic domains, optimizes the surface displacement of the ASV and the depth of its probe by solving a constrained multi-objective optimization problem that minimizes the mission duration and trajectory length, maximizes the possibilities of the probe to overpass areas with high concentration of cyanobacteria, and satisfies operational constraints (such as ASV velocity or acceleration limits, and obstacle avoidance). The optimization is supported by two well-known versions of the Non-Sorted Generic Algorithm (NSGA-II and NSGA-III) and by encoding the trajectories with spline curves whose number of control points can be fixed, progressively increased, or freely manipulated by the algorithm. The performance of different configurations of the planner is tested against six scenarios obtained from different simulations of the multiphysics model (which couples water dynamics and temperature, light transmission, daily vertical migration of the cyanobacteria and their growth). The statistical analysis of the planner results determines that NSGA-III working with variable-length chromosomes and NSGA-II with the progressive increment of spline points as the best configurations for maximizing cyanobacteria detection, and minimizing mission duration and trajectory length. Full article
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35 pages, 24919 KB  
Article
High-Precision and Efficient Calibration of Robot Polishing Systems Using an Adaptive Residual EKF Optimized by MIPO
by Lei Wang, Yuqi Yao, Shouxin Ruan, Hainan Li, Xinming Zhang, Yiwen Zhang, Zihao Zang and Zhenglei Yu
Sensors 2026, 26(10), 3087; https://doi.org/10.3390/s26103087 - 13 May 2026
Viewed by 608
Abstract
This paper proposes an adaptive residual extended Kalman filter method optimized by a multi-strategy improved parrot optimization algorithm (MIPO-ARKEKF) to improve the kinematic parameter calibration accuracy and efficiency of robotic polishing systems. To address the limitations of the standard extended Kalman filter (EKF), [...] Read more.
This paper proposes an adaptive residual extended Kalman filter method optimized by a multi-strategy improved parrot optimization algorithm (MIPO-ARKEKF) to improve the kinematic parameter calibration accuracy and efficiency of robotic polishing systems. To address the limitations of the standard extended Kalman filter (EKF), such as truncation-error accumulation during repeated linearization and sensitivity to manually selected noise parameters, an integrated improvement framework is developed. Specifically, a gradient stabilizer based on state-estimation increments is introduced to alleviate estimation degradation caused by accumulated truncation errors, while the proposed MIPO algorithm is employed to adaptively optimize the process and measurement noise covariance matrices, thereby improving the robustness of parameter identification under practical measurement uncertainty. The calibration process is established on the basis of high-precision external measurement data obtained from the robotic polishing system. In benchmark-function tests, MIPO demonstrates superior convergence performance. In physical experiments based on a KUKA KR210 R2700 robot, the proposed MIPO-ARKEKF method reduces the root mean square positioning error from 0.8927 mm to 0.4858 mm, corresponding to a 45.58% improvement in accuracy. Compared with representative hybrid calibration methods, the proposed method achieves comparable compensation accuracy while reducing computation time by 34.88% to 65.08%. Practical polishing experiments on ultra-low-expansion glass lenses further verify that the proposed method effectively improves end-effector trajectory tracking accuracy and polishing quality, providing an efficient solution for high-precision robotic polishing. Full article
(This article belongs to the Section Sensors and Robotics)
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14 pages, 262 KB  
Article
No-Touch Adaptive Versus Conventional Robot-Assisted Partial Nephrectomy for Localized Renal Tumours with High Nephrometry Complexity: A Comparative Analysis of Early Outcomes
by Gianluca Giannarini, Alessandro Crestani, Giuliana Lista, Paolo Corsi, Gioacchino De Giorgi, Davide Minardi, Luca Di Gianfrancesco, Davide De Marchi, Antonio Amodeo and Angelo Porreca
Cancers 2026, 18(10), 1577; https://doi.org/10.3390/cancers18101577 - 12 May 2026
Cited by 1 | Viewed by 448
Abstract
Background/Objectives: Surgical refinements in robot-assisted partial nephrectomy (RAPN) aim to reduce morbidity and optimize renal function preservation, particularly in patients with high-complexity renal tumours. This study describes the no-touch adaptive technique for RAPN and compares its perioperative outcomes, postoperative complications, and resulting [...] Read more.
Background/Objectives: Surgical refinements in robot-assisted partial nephrectomy (RAPN) aim to reduce morbidity and optimize renal function preservation, particularly in patients with high-complexity renal tumours. This study describes the no-touch adaptive technique for RAPN and compares its perioperative outcomes, postoperative complications, and resulting early renal function with those of the conventional approach. Methods: A cohort of 72 consecutive patients with high-complexity renal tumours undergoing RAPN was evaluated. The study group included 38 patients treated with the no-touch adaptive technique, while 34 patients underwent the conventional approach. The no-touch adaptive technique consisted of sutureless, off-clamp, simple tumour enucleation with incremental haemostasis and the option to shift to arterial clamping, tumour enucleoresection, or renorrhaphy as needed. The conventional technique involved on-clamp minimal enucleoresection with double-layer renorrhaphy. Outcomes assessed included completion of a fully no-touch procedure, perioperative metrics, 90-day postoperative complications, and 3-month renal function change from baseline. Results: Baseline characteristics were comparable between groups. A fully no-touch RAPN was achieved in 30/38 (79%) patients. Adaptations were required in eight cases: shift to main arterial clamping (n = 2), renorrhaphy (n = 5), or both (n = 1), with one conversion to total nephrectomy due to intractable bleeding. Estimated blood loss was similar between groups (study: 150 mL [IQR 75–250] vs. control: 180 mL [IQR 100–400]). Length of stay was significantly shorter in the study group (3 days [IQR 3–4]) compared with controls (5 days [IQR 6–8]). Any-grade 90-day complications were significantly lower with the no-touch technique (21% vs. 56%, p < 0.01). Clinically significant 3-month eGFR decline occurred in 14% of controls versus 0% of study patients (p = 0.02). Conclusions: The no-touch adaptive RAPN technique is feasible in high-complexity renal tumours and provides reduced morbidity and superior early renal function preservation compared with the conventional approach. Full article
25 pages, 1444 KB  
Article
A Lightweight Robotic Process Automation Framework for Financial Analytics in Spreadsheet-Centric SMEs
by Sumukhi Nandam and Carlos D. Paternina-Arboleda
Information 2026, 17(5), 468; https://doi.org/10.3390/info17050468 - 12 May 2026
Viewed by 755
Abstract
Small and medium-sized enterprises (SMEs) frequently depend on spreadsheet-based financial reporting due to limited budgets and constrained access to enterprise analytics systems. As transaction volumes increase, manual profit and loss computation becomes time-intensive and prone to inconsistencies. This study proposes and evaluates a [...] Read more.
Small and medium-sized enterprises (SMEs) frequently depend on spreadsheet-based financial reporting due to limited budgets and constrained access to enterprise analytics systems. As transaction volumes increase, manual profit and loss computation becomes time-intensive and prone to inconsistencies. This study proposes and evaluates a modular robotic process automation (RPA) framework designed to enhance spreadsheet-centric financial analytics without requiring enterprise system replacement. The framework is implemented as a unified pipeline using UiPath. Statistical anomaly detection mechanisms are integrated to identify abnormal revenue deviations and expense spikes in operational data. Experimental benchmarking compares manual spreadsheet processing with automated workflow execution using execution time, error exposure, reporting latency, and scalability as evaluation criteria. Empirical evaluation across five datasets spanning 300 to 3000 transactions demonstrates time reductions of 88.6% to 95.5% and error reductions of 93.3% to 95.5% relative to manual spreadsheet processing. Scalability analysis confirms linear growth of automated runtime with transaction volume, in contrast to the superlinear growth observed in manual processing. A cost feasibility analysis further indicates that lightweight RPA can significantly reduce operational costs in SME environments up to 88.6%. The study contributes a structured automation architecture that integrates spreadsheet automation with statistical monitoring to support financial oversight and decision support. The findings suggest that interface-level automation provides a viable transitional pathway for SMEs seeking incremental digital transformation while preserving existing spreadsheet infrastructures. Full article
(This article belongs to the Section Information Applications)
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16 pages, 11409 KB  
Article
Design and Analysis of an Axial Flux Permanent Magnet Synchronous Motor with a Stepped Stator Structure for Cogging Torque Reduction
by Seung-Hoon Ko, Kan Akatsu, Ho-Joon Lee, Gu-Young Cho and Won-Ho Kim
Actuators 2026, 15(5), 240; https://doi.org/10.3390/act15050240 - 29 Apr 2026
Viewed by 814
Abstract
The Axial Flux Permanent Magnet Synchronous Motor (AFPMSM) has gained significant attention as a core power source for next-generation industrial sectors, including electric vehicles, wind turbines, robot joints, and drone propulsion motors, due to its high power density from a short axial length [...] Read more.
The Axial Flux Permanent Magnet Synchronous Motor (AFPMSM) has gained significant attention as a core power source for next-generation industrial sectors, including electric vehicles, wind turbines, robot joints, and drone propulsion motors, due to its high power density from a short axial length and large radial dimensions. Despite these structural advantages, cogging torque caused by magnetic interaction between the stator teeth and permanent magnets remains a critical drawback, inducing noise and vibration. While conventional Soft Magnetic Composite (SMC) core methods facilitate 3D flux paths, they suffer from low magnetic permeability, insufficient mechanical strength, and manufacturing complexity. To address these issues, this study proposes a stepped structure model utilizing electrical steel sheets to effectively reduce cogging torque. This structure features radial stacking of identical electrical steel sheets with varying widths, where each layer’s center is incrementally shifted in the rotational direction. This configuration achieves an effect analogous to continuous skewing without specialized 3D machining. To validate the proposed design, 3D Finite Element Analysis (FEA) was conducted. Results demonstrate that the peak-to-peak cogging torque was reduced to approximately 86% of the conventional model’s value, while maintaining the back-EMF reduction rate within 5%. By presenting a novel skewing technique, this research provides a practical alternative for high-precision and high-power AFPMSM. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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27 pages, 2173 KB  
Article
Efficient Incremental SLAM via Information-Guided Gating and Selective Partial Optimization
by Reza Arablouei
Robotics 2026, 15(5), 87; https://doi.org/10.3390/robotics15050087 - 27 Apr 2026
Viewed by 630
Abstract
We present an efficient incremental SLAM back-end that reduces computation while preserving accuracy close to that of a full incremental Gauss–Newton (GN) solver across benchmark pose-graph datasets. The method combines information-guided gating (IGG), which uses a log-determinant-based information surrogate to decide when broad [...] Read more.
We present an efficient incremental SLAM back-end that reduces computation while preserving accuracy close to that of a full incremental Gauss–Newton (GN) solver across benchmark pose-graph datasets. The method combines information-guided gating (IGG), which uses a log-determinant-based information surrogate to decide when broad updates are warranted, with selective partial optimization (SPO), which confines multi-iteration GN updates to variables that remain affected after each iteration. We provide a local perturbation analysis, showing that, under standard regularity conditions, the proposed approximation tracks full GN within a threshold-controlled neighborhood and recovers the same local minimizer and asymptotic convergence rate when the effective approximation error vanishes asymptotically. Experiments on benchmark pose-graph SLAM datasets show competitive final and increment-averaged accuracy together with substantial reductions in update and solve FLOPs. These results support IGG-SPO as a practically promising SLAM back-end for robots operating under limited onboard computational resources. Full article
(This article belongs to the Special Issue State of the Art in Mobile Robot Localization)
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26 pages, 3483 KB  
Article
Influence of Tool-Axis Orientation on Dimensional Accuracy in Robot-Based Single Point Incremental Forming
by Alexandru Bârsan, Iosif-Adrian Maroșan, Sever-Gabriel Racz, Radu-Eugen Breaz, Mihai Crenganiș, Mihai-Octavian Popp, Gabriela-Petruța Popp and Diana-Maria Tatu
Materials 2026, 19(9), 1761; https://doi.org/10.3390/ma19091761 - 26 Apr 2026
Viewed by 601
Abstract
Single point incremental forming (SPIF) represents a flexible manufacturing process capable of producing complex sheet metal parts without the need for dedicated forming dies. However, achieving high dimensional accuracy remains a major challenge due to phenomena such as elastic springback and localized deformation. [...] Read more.
Single point incremental forming (SPIF) represents a flexible manufacturing process capable of producing complex sheet metal parts without the need for dedicated forming dies. However, achieving high dimensional accuracy remains a major challenge due to phenomena such as elastic springback and localized deformation. In this context, the present study investigates the influence of tool-axis orientation on the dimensional accuracy of parts manufactured through robot-based single point incremental sheet forming (RB-SPIF). The experimental analysis considered two toolpath strategies (contour and spiral), two vertical step sizes (0.5 mm and 1 mm), and two tool-axis configurations (fixed tool-axis and wall-normal tool-axis orientation), resulting in eight experimental cases. The dimensional accuracy of the manufactured parts was evaluated using optical 3D scanning and cross-sectional profile analysis. The results show that the vertical step size has a significant influence on the resulting geometry, with smaller step sizes generating profiles closer to the nominal geometry. The toolpath strategy also affects the geometry, with spiral trajectories generally producing slightly improved profiles compared to contour strategies; however, this effect was not found to be statistically significant under the investigated conditions. Furthermore, the use of a wall-normal tool-axis configuration improves the agreement between the measured and nominal profiles by enhancing the contact conditions between the tool and the metal sheet surface. These findings indicate that adaptive tool-axis orientation represents a promising strategy for improving the dimensional accuracy of parts produced by robot-based incremental sheet forming systems. Full article
(This article belongs to the Special Issue Plastic Deformation and Mechanical Properties of Metallic Materials)
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34 pages, 5833 KB  
Article
High-Level Synthesis-Based FPGA Hardware Accelerator for Generalized Hebbian Learning Algorithm for Neuromorphic Computing
by Shivani Sharma and Darshika G. Perera
Electronics 2026, 15(8), 1725; https://doi.org/10.3390/electronics15081725 - 18 Apr 2026
Viewed by 1394
Abstract
With the advent of AI and the smart systems era, neuromorphic computing will be imperative to support next-generation AI-related applications. Existing intelligent systems, (such as smart cities, robotics), face many challenges and requirements including, high performance, adaptability, scalability, dynamic decision-making, and low power. [...] Read more.
With the advent of AI and the smart systems era, neuromorphic computing will be imperative to support next-generation AI-related applications. Existing intelligent systems, (such as smart cities, robotics), face many challenges and requirements including, high performance, adaptability, scalability, dynamic decision-making, and low power. Neuromorphic computing is emerging as a complementary solution to address these challenges and requirements of next-gen intelligent systems. Neuromorphic computing comprises many traits, such as adaptive, low-power, scalable, parallel computing, that satisfies the requirements of future intelligent systems. There is a need for innovative solutions (in terms of models, architectures, techniques) for neuromorphic computing to support next-gen intelligent systems to overcome several challenges hindering the advancement of neuromorphic computing. In this research work, we introduce a novel and efficient FPGA-HLS-based hardware accelerator for the Generalized Hebbian learning algorithm (GHA) for neuromorphic computing applications. We decided to focus on GHA, since it was demonstrated that GHA enables online and incremental learning, and provides a hardware-efficient unsupervised learning framework that aligns closely with the principles of biological adaptation—traits that are vital for neuromorphic computing applications. In addition, our previous work showed that FPGAs have many features, such as low power, customized circuits, parallel computing capabilities, low latency, and especially adaptive nature, which make FPGAs suitable for neuromorphic computing applications. We propose two different hardware versions of FPGA-HLS-based GHA hardware accelerators: one is memory-mapped interface-based and another one is streaming interface-based. Our streaming interface-based FPGA-HLS-based GHA hardware IP achieves up to 51.13× speedup compared to its embedded software counterpart, while maintaining small area and low power requirements of neuromorphic computing applications. Our experimental results show great potential in utilizing FPGA-based architectures to support neuromorphic computing applications. Full article
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36 pages, 1727 KB  
Article
Smart Cities in the Agentic AI Era: Three Vectors of Urban Transformation
by Esteve Almirall
Appl. Sci. 2026, 16(8), 3847; https://doi.org/10.3390/app16083847 - 15 Apr 2026
Viewed by 1599
Abstract
Agentic artificial intelligence—systems that reason, plan, and act autonomously within governed workflows—is converging with autonomous electric mobility and urban robotics to reshape how cities govern, move, and manage physical space. We argue that the simultaneous arrival of these three vectors is triggering a [...] Read more.
Agentic artificial intelligence—systems that reason, plan, and act autonomously within governed workflows—is converging with autonomous electric mobility and urban robotics to reshape how cities govern, move, and manage physical space. We argue that the simultaneous arrival of these three vectors is triggering a transformation comparable in scope to the Industrial Revolution. Cities that deploy across all three domains are becoming the new hubs of innovation: they concentrate talent, accelerate knowledge circulation, enable cross-fertilisation, and generate hybrid proposals that no single vector could produce alone. Just as Manchester, Birmingham, and the Ruhr became the defining centres of industrialisation because steam, textiles, iron, and coal recombined through the proximity of the engineers and entrepreneurs who moved between them, a small number of cities today are pulling ahead because they host the shared talent pool around which agentic governance, autonomous mobility, and urban robotics co-evolve. Conceptually, we extend the mirroring hypothesis in two directions: dynamically, arguing that organisations and urban ecosystems converge toward the configurations new technologies make possible; and ontologically, arguing that agentic AI introduces non-human agents into organisational architectures, requiring hybrid human–AI coordination. We formalise this dynamic as five propositions (P1–P5) of cumulative recursive hybridisation (CRH), operating through four reinforcing feedback loops—data, regulation, infrastructure, and talent. Together, these loops explain why the emerging urban order is path-dependent: early movers accumulate compounding advantages, while latecomers face exponentially rising costs of entry. We demarcate CRH from adjacent frameworks—general-purpose technologies, organisational complementarities, and complex adaptive systems—and test it against counterfactual evidence from failed, stalled, and Global South trajectories (Sidewalk Toronto, the Cruise rollback, Songdo, Bengaluru). We also examine its political-economy, equity, and surveillance limits. Drawing on comparative evidence from public-sector chatbot deployments, autonomous mobility ecosystems in the United States and China, and emerging urban robotics cases, we conclude that what is at stake is not incremental modernisation but the construction of a new urban order. The cities that act as innovation hubs for the agentic AI era will shape global standards, attract global talent, and define the institutional templates that others eventually adopt—much as the industrial cities of the eighteenth and nineteenth centuries did. Full article
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26 pages, 6083 KB  
Article
Gait Optimization Control of Spinal Quadruped Robot Based on Deep Reinforcement Learning
by Guozheng Song, Qinglin Ai, Lin Li, Xiaohang Shan, Chao Yang and Jianguo Yang
Sensors 2026, 26(8), 2407; https://doi.org/10.3390/s26082407 - 14 Apr 2026
Viewed by 646
Abstract
The spine enhances the flexibility of quadrupeds during locomotion. Inspired by this biological mechanism, this study incorporates an actuated spinal joint into a quadruped robot, enabling more natural motion and posture adjustment. To improve the motion stability of spinal robots in complex environments, [...] Read more.
The spine enhances the flexibility of quadrupeds during locomotion. Inspired by this biological mechanism, this study incorporates an actuated spinal joint into a quadruped robot, enabling more natural motion and posture adjustment. To improve the motion stability of spinal robots in complex environments, a deep reinforcement learning framework that integrates a central pattern generator (CPG) with the twin delayed deterministic policy gradient (TD3) algorithm is proposed to optimize the gait motion of the spinal quadruped robot. First, the structure and parameters of the quadruped robot with a spinal joint are analyzed and a CPG coupling model incorporating spinal motion parameters is designed. Subsequently, a TD3–CPG algorithm framework based on a joint incremental strategy is proposed to optimize the robot’s gait, exploring optimal control strategies for terrain adaptation through spinal motion integration. Finally, experiments are conducted on various obstacle terrains to validate the proposed algorithm. Simulation and experiment results demonstrate the effectiveness of the algorithm in optimizing the gait of the spinal quadruped robot, showing significant improvements in walking stability, speed, and terrain adaptability across different terrains. Full article
(This article belongs to the Section Sensors and Robotics)
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20 pages, 2638 KB  
Article
Design and Implementation of Underwater Robotic Systems for Visual–Inertial Trajectory Estimation and Robust Motion Control
by Yangyang Wang, Tianzhu Gao, Yongqiang Zhao, Ziyu Liu, Hang Yu and Xijun Du
Symmetry 2026, 18(4), 621; https://doi.org/10.3390/sym18040621 - 6 Apr 2026
Viewed by 800
Abstract
Reliable trajectory estimation and precise motion control are the prerequisites for underwater robotic systems to perform complex autonomous tasks, which are essential for enhancing the operational efficiency of intelligent underwater facilities. However, the inherent asymmetry of underwater hydrodynamics, featureless images caused by complex [...] Read more.
Reliable trajectory estimation and precise motion control are the prerequisites for underwater robotic systems to perform complex autonomous tasks, which are essential for enhancing the operational efficiency of intelligent underwater facilities. However, the inherent asymmetry of underwater hydrodynamics, featureless images caused by complex environments, and the lack of high-frequency state feedback significantly hinder stable trajectory tracking and robust autonomous navigation. To address these challenges, this paper proposes an integrated autonomous navigation and robust control scheme for underwater robotic systems. Specifically, we first propose a visual–inertial trajectory estimation method for underwater robotic systems, which effectively overcomes the challenges of featureless images and provides consistent, real-time pose feedback for motion execution. Furthermore, we develop a hierarchical robust motion control strategy for autonomous underwater robots, which integrates model predictive control with incremental nonlinear dynamic inversion to achieve precise positioning performance and reliable operation under environmental disturbances. Finally, we design and implement a customized, highly integrated underwater robotic platform that integrates the proposed trajectory estimation and robust control modules, with its performance validated through extensive field experiments in underwater scenarios. The experimental results demonstrate that the proposed system can effectively achieve high-precision trajectory tracking and maintain operational stability, providing a comprehensive engineering solution for the autonomous navigation of underwater robots in complex environments. Full article
(This article belongs to the Special Issue Symmetry in Next-Generation Intelligent Information Technologies)
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43 pages, 18679 KB  
Article
Fast Convergence Adaptive Approach for Real-Time Motion Planning
by Kashif Khalid, Yasar Ayaz, Umer Asgher, Vladimír Socha, Sara Ali and Khawaja Fahad Iqbal
Robotics 2026, 15(4), 73; https://doi.org/10.3390/robotics15040073 - 1 Apr 2026
Viewed by 886
Abstract
Real-time motion planning in cluttered and dynamically evolving environments remains challenging due to the need to ensure rapid convergence, collision avoidance, computational efficiency, and robustness against local minima under frequent changes. Although sampling-based planners such as RRTX* and ABIT* provide strong theoretical guarantees, [...] Read more.
Real-time motion planning in cluttered and dynamically evolving environments remains challenging due to the need to ensure rapid convergence, collision avoidance, computational efficiency, and robustness against local minima under frequent changes. Although sampling-based planners such as RRTX* and ABIT* provide strong theoretical guarantees, their practical deployment in dense dynamic scenarios is often limited by high sampling overhead and computational latency. This paper proposes a Fast Converging Adaptive Algorithm (FCAA), a deterministic sampling-based framework integrating adaptive sampling density, temperature-controlled exploration, and dynamic step-size regulation within a unified heating and annealing mechanism. The temperature parameter governs both the spatial sampling band and incremental expansion radius, enabling controlled transitions between goal-directed expansion and stochastic exploration when stagnation occurs. The algorithm is evaluated using a two-stage protocol comprising intrinsic validation and benchmarking. Across 36 environments with obstacle densities ranging from 3% to 20% and velocities between −30 and +30 m/s, FCAA achieved a 100% success rate within the defined experimental design while maintaining path quality comparable to or better than RRTX* and ABIT*. Unlike the reference planners, which typically required tens of thousands of samples and seconds of computation, FCAA operated with substantially reduced sampling effort, typically tens of nodes, and planning times from 0.1 to 320 ms depending on scenario complexity. Within the simulation framework, the results indicate that the proposed temperature-regulated strategy enables fast and computationally efficient motion planning under dynamic constraints, making FCAA suitable for time-critical robotic navigation scenarios. Full article
(This article belongs to the Topic Advances in Mobile Robotics Navigation, 2nd Volume)
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15 pages, 8090 KB  
Article
Adaptive Multi-Sensor Fusion Localization with Eigenvalue-Based Degradation Detection for Mobile Robots
by Weizu Huang, Long Xiang, Ruohao Chen, Sheng Xu and Qing Wang
Sensors 2026, 26(5), 1653; https://doi.org/10.3390/s26051653 - 5 Mar 2026
Cited by 1 | Viewed by 1853
Abstract
Autonomous mobile robots require robust localization in complex and dynamic environments, where single-sensor solutions often fail due to accumulated drift or signal degradation. LiDAR–inertial odometry provides accurate short-term motion estimation, but suffers from long-term error accumulation, whereas RTK-GNSS offers absolute positioning that becomes [...] Read more.
Autonomous mobile robots require robust localization in complex and dynamic environments, where single-sensor solutions often fail due to accumulated drift or signal degradation. LiDAR–inertial odometry provides accurate short-term motion estimation, but suffers from long-term error accumulation, whereas RTK-GNSS offers absolute positioning that becomes unreliable under occlusion or multipath effects. To solve the above problems, this paper proposes an adaptive multi-sensor fusion positioning framework that dynamically fuses LiDAR, IMU, and RTK-GNSS data based on the real-time quality evaluation of sensors. The system uses the front-end tightly coupled LiDAR–IMU iterative extension Kalman filter (IEKF) as the core estimator and combines loop detection with incremental factor graph optimization to suppress long-term drift. In addition, a degradation detection method based on the minimum eigenvalue of the Jacobian matrix is proposed to identify unreliable matching constraints in real time. In order to avoid abrupt changes in positioning results caused by fluctuations in sensor data quality, the system adopts a smooth fusion strategy based on covariance weighting. Experiments on the KITTI benchmark and self-collected datasets demonstrate that the proposed method significantly improves localization accuracy and robustness compared with pure LiDAR-based approaches, achieving stable centimeter-level performance while maintaining real-time capability on embedded platforms. Full article
(This article belongs to the Section Sensors and Robotics)
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