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Design of a SMA actuated freeplay elimination device for stiffness enhancement of a folding fin

Mechanical systems and Signal Processing 2025年 234卷

作者： Zhang, Rongru Chen, Gang Yue, Honghao Si, Mingyu State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin150001 China Beijing Institute of Electronic System Engineering Beijing100854 China

The folding fin, essential for controlling aircraft flight attitude and maintaining stability, is extensively employed in aerospace vehicles. Inevitable freeplay within the structure, due to design, installation, and mechanical wear, reduce the stiffness of the folding fins and impair the aircraft's aerodynamic performance. Therefore, eliminating the freeplay in the folding fin is crucial for enhancing the aircraft's flight accuracy and stability. This paper introduces a novel freeplay elimination device utilizing SMA columns, which neither increases mass nor alters the aircraft's external dimensions. The device effectively alleviates nonlinear issues associated with gaps in the fin system and enhances both the dynamic and static stiffness of the folding fin. A parametric design model for the gap elimination device has been developed, delineating the relationship between the structure and layout of the SMA columns, the actuation temperature, load, and the target gap for elimination. We conducted static load tests along with modal tests at room and elevated temperatures to evaluate the stiffness enhancement performance of the folding fin before and after gap elimination. The experiments verified that the designed gap elimination device significantly enhances both the static and dynamic stiffness of the folding fin. Additionally, the first-order frequency of the folding fin increased by 40 % at room temperature and by 36.7 % at 200 °C. This paper provides quantifiable guidance for the structural and parametric design of gap elimination devices in folding fins. Optimal structural parameters, determined based on aerodynamic loads and gap elimination requirements, enhance the stiffness of the folding fin, thus improving the aircraft's flight performance. © 2025

关键词： Freewing aircraft

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Layered structural engineering of Bi 2 O 3 /PP and WO 3 /PP composites for γ-ray shielding in high energy range: anisotropic attenuation mechanisms via Monte Carlo simulation and experiments

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Journal of Materials Research and Technology 2025年 36卷 10324-10336页

作者： Xiangjie Duan Jie Zhao Shuaida Song Na Zhou Jizhuang Fan Bo Tian Yunchen Du State Key Laboratory of Space Power-Sources School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 People's Republic of China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150006 People's Republic of China Heilongjiang Institute of Atomic Energy Heilongjiang Academy of Sciences Harbin 150081 People's Republic of China

The development of non-toxic and flexible polymer-based shielding composites has become a research hotspot due to the severe harm of γ ray to living organisms, mechanical equipment, and environment. However, the γ-ray shielding performance of polymer-based composites in high-energy range remains unsatisfactory. Herein, FLUKA Monte Carlo simulations capable of visualizing γ-photon transport behaviors are investigated in Bi 2 O 3 /PP and WO 3 /PP multi-layer composites with various layered configurations. The simulation results reveal significant anisotropic attenuation effects on shielding characteristics caused by layered configurations and incident path of γ-photons relative to the interface position. Subsequently, single-layer, AB, and sandwich-like ABA composites with a fixed thickness of 2.0 mm are experimentally fabricated via melt-mixing and hot press methods. At 1332 keV, sandwich-like WPPBPPWPP composite (WO 3 /PP outer layers + Bi 2 O 3 /PP core) achieves linear attenuation coefficients and radiation protection efficiency of 0.31 cm −1 and 6 %, respectively, which are 29 % higher than those of single-layer composite. These improvements originate from multiple scattering induced by interlayer interface. Additionally, layered configurations with externally placed high-density fillers (WO 3 ) and internally placed high atomic number fillers (Bi 2 O 3 ) further promote γ-photon attenuation in high-energy range. Experimental results validate the anisotropic shielding trends observed in MC simulations. Moreover, multi-layer composites demonstrate significantly improved energy storage capacity, thermal stability, and oxidation resistance while maintaining comparable to those of single-layer composites. This work provides a scalable strategy for developing non-toxic and flexible shielding materials applicable in nuclear protection, medical devices, and aerospace systems, where lightweight and efficient radiation attenuation are critical.

关键词： Polymer-based composites Multi-layer structural engineering γ-Ray shielding Monte Carlo simulation Anisotropy attenuation Heterogeneous interface

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An Iterative Task-Driven Framework for Resilient LiDAR Place Recognition in Adverse Weather

arXiv

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arXiv 2025年

作者： Zhao, Xiongwei Wang, Yang Sun, Qihao Bai, Haojie Xie, Xingxiang Shenzhen518071 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150006 China School of Information Communication Technology Shenzhen Institute of Information Technology Shenzhen518071 China

LiDAR place recognition (LPR) plays a vital role in autonomous navigation. However, existing LPR methods struggle to maintain robustness under adverse weather conditions such as rain, snow, and fog, where weather-induced noise and point cloud degradation impair LiDAR reliability and perception accuracy. To tackle these challenges, we propose an Iterative Task-Driven Framework (ITDNet), which integrates a LiDAR Data Restoration (LDR) module and a LiDAR Place Recognition (LPR) module through an iterative learning strategy. These modules are jointly trained end-to-end, with alternating optimization to enhance performance. The core rationale of ITDNet is to leverage the LDR module to recover the corrupted point clouds while preserving structural consistency with clean data, thereby improving LPR accuracy in adverse weather. Simultaneously, the LPR task provides feature pseudo-labels to guide the LDR module’s training, aligning it more effectively with the LPR task. To achieve this, we first design a task-driven LPR loss and a reconstruction loss to jointly supervise the optimization of the LDR module. Furthermore, for the LDR module, we propose a Dual-Domain Mixer (DDM) block for frequency-spatial feature fusion and a Semantic-Aware Generator (SAG) block for semantic-guided restoration. In addition, for the LPR module, we introduce a Multi-Frequency Transformer (MFT) block and a Wavelet Pyramid NetVLAD (WPN) block to aggregate multi-scale, robust global descriptors. Finally, extensive experiments on the Weather-KITTI, Boreas, and our proposed Weather-Apollo datasets demonstrate that, demonstrate that ITDNet outperforms existing LPR methods, achieving state-of-the-art performance in adverse weather. The datasets and code will be made publicly available at https://***/Grandzxw/ITDNet. © 2025, CC BY.

关键词： Image coding

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Evaluation of motor unit tracking across hand movements by combining high-density surface electromyography with ultrafast ultrasound

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Computers in Biology and Medicine 2025年 193卷 110325-110325页

作者： Yin, Zongtian Chen, Chen Meng, Jianjun Zhu, Xiangyang State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China Meta Robotics Institute Shanghai Jiao Tong University Shanghai China

Objective: Motor unit (MU) activities provide the primary output from the central nervous system to muscles, and have found wide applications in neurophysiological investigation and human-machine interface. However, the current decoding methods usually struggle with MU tracking across movements. A common compromise is comparing motor unit action potentials extracted from electromyography (EMG) signals, but this only considers electrical responses and requires further validation. This study aims to simultaneously collect EMG and ultrasound (US) signals, extracting both electrical and mechanical responses of MU discharges, to validate their feasibility for MU tracking across movements. Methods: Ten able-bodied subjects participated in experiments involving isometric contraction of six hand movements. High-density surface EMG signals and ultrafast US images were concurrently recorded from the forearm muscles. The EMG signals were decomposed into MU spike trains and the separation vectors were kept for MU decoding across movements. The three-dimensional activation zone of each MU, including the action potentials on the skin surface and the twitch area in the muscle cross-sections, was extracted to validate the tracking performance. Main results: On average, 37 ± 17 MUs were identified from each decomposition, of which 20±16,2±2, and 2 ± 1 MUs were successfully tracked based on action potential, twitch area, and both, respectively. Conclusion and Significance: These results demonstrate strong evidence for the feasibility of tracking MUs using pre-trained separation vectors, supported by both electrical and mechanical responses. In addition, the study provides a benchmark to track MU activities across hand movements, extending the potential applications of neural decoding in neurophysiological investigation and human-machine interfacing. © 2025 Elsevier Ltd

关键词： Blind source separation

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Study on wear mechanism of small ball-end grinding wheel and surface integrity of complex component under high-speed machining condition

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Wear 2025年

作者： Qin, Biao Liu, Henan Cheng, Jian Tian, Jinchuan Sun, Jiangang Chen, Mingjun School of Mechatronics Engineering Harbin Institute of Technology Heilongjiang Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China Zhengzhou Research Institute Harbin Institute of Technology Zhengzhou450000 China

The small ball-end fine diamond grinding wheel is well-suited for machining complex components with small curved surface structures, demonstrating high-precision and high-quality machining capabilities. By increasing the speed of the workpiece, the issue of poor grinding performance caused by the small diameter of the ball-end grinding wheel can be effectively overcome. However, this strategy inevitably increases wheel wear and affects surface integrity. To address these challenges, this paper systematically investigates the grinding characteristics of the small ball-end grinding wheel. First, grinding experiments were performed to investigate the influence of workpiece speed, feed rate, and grinding depth on the material removal rate, wheel wear, and surface integrity. Then, the wear mechanism of the grinding wheel was analyzed. The wear modes of the grinding wheel at high workpiece speeds include metal adhesive wear and abrasive grain fracture, which enhance the self-sharpening of the grinding wheel while accelerating its wear. Furthermore, the surface morphology creation mechanism of fused silica under different material removal modes was revealed. Moreover, the correlation between material removal rate and surface roughness caused by wheel wear was revealed. A high-speed grinding strategy was subsequently proposed based on the relationship between the grinding characteristics and grinding parameters of the small ball-end grinding wheel under various grinding conditions. Finally, the feasibility of this grinding strategy was validated through its application to the machining of the complex curved fused silica hemispherical resonator (HSR). Experimental results indicate that under the high workpiece speed condition, the best surface roughness of HSR decreases from 90.5 nm to 62.2 nm, while the maximum grinding wheel wear increases from 9.7 μm to 11.5 μm, with minimal impact on surface integrity. Therefore, the high-speed grinding strategy proposed in this study ho

关键词： Fused silica

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Ultrahigh energy density and rapid response dielectric elastomer for advanced soft robots

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Chemical Engineering Journal 2025年 515卷

作者： Du, Chengzhen Yan, Peinan Zou, Jiang Guo, Yutong Pang, Zimo Li, Sijia Chen, Yujie Fan, Qunfu Liu, Hezhou State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Robotics Institute State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China National Engineering Research Center of Special Equipment and Power System for Ship and Marine Engineering Shanghai200030 China

Dielectric elastomer actuators (DEAs) require high energy density to simultaneously achieve high mechanical output while enabling compact and lightweight actuator design. However, the realization of high energy density is constrained by the high driving electric field and the significant hysteretic relaxation. Herein, we present a DE featuring a bimodal-network structure and multiple hydrogen bonds interactions, which possesses outstanding properties, including a low Young's modulus, optimal dielectric properties, and low mechanical loss. The DE achieves a maximum actuation strain of 200 % at a low driving electric field of 60 V μm−1 with a rapid response. Remarkably, it exhibits an output force of 0.95 N and an ultrahigh specific energy of 283 J kg−1, approximately 7 times that of natural muscle. A series of soft robots with different structures and functions are fabricated to showcase the immense potential of our DE in various applications. This work provides a novel strategy to fabricate high performance artificial muscles for soft robotics. © 2025 Elsevier B.V.

关键词： Dielectric properties of solids

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Ultrahigh Energy Density and Rapid Response Dielectric Elastomer for Advanced Soft Robots

SSRN

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SSRN 2025年

Dielectric elastomer actuators (DEAs) require high energy density to simultaneously achieve high mechanical output while enabling compact and lightweight actuator design. However, the realization of high energy density is constrained by the high driving electric field and the significant hysteretic relaxation. Herein, we present a DE featuring a bimodal-network structure and multiple hydrogen bond interactions, which possesses outstanding properties, including a low Young's modulus, optimal dielectric properties, and low mechanical loss. The DE achieves a maximum actuation strain of 200% at a low driving electric field of 60 V μm-1 with a rapid response. Remarkably, it exhibits an output force of 0.95 N and an ultrahigh specific energy of 283 J kg-1, approximately 7 times that of natural muscle. A series of soft robots with different structures and functions are fabricated to showcase the immense potential of our DE in various applications. This work provides a novel strategy to fabricate high performance artificial muscles for soft robotics. © 2025, The Authors. All rights reserved.

关键词： Elastomers

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Practical Applicability of PLA for Industrial Wireless Networks: Gaps and Directions

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IEEE Network 2025年

作者： Liang, Wei Wei, Fuyou Wang, Qi Zhan, Ming Wang, Ke Chinese Academy of Sciences State Key Laboratory of Robotics Shenyang Institute of Automation Shenyang110016 China Chinese Academy of Sciences Key Laboratory of Networked Control System Shenyang Institute of Automation Shenyang110016 China Chinese Academy of Sciences Institutes for Robotics and Intelligent Manufacturing Shenyang110169 China University of Chinese Academy of Sciences Beijing100049 China Shandong Normal University Jinan250014 China Taizhou University School of Electronics and Information Engineering Zhejiang Taizhou China

The rapid transformation of Industrial Cyber-Physical system (ICPS) has introduced significant cyber security challenges, particularly in the context of ICPS. Wireless networks are a critical component of these systems, but their open nature makes them vulnerable to security threats. Physical Layer Authentication (PLA) algorithms based on Channel state Information (CSI) are essential complements to existing security technologies in wireless networks. However, their practical application faces challenges such as restricted sampling rates and uneven sampling interval, which result in low-precision CSI, significant random phase offsets, and signal distortion. This study aims to explore the feasibility of deploying and applying existing representative algorithms on industrial wireless commercial devices. According to characteristics of authentication algorithms and the adopted authentication features, we selected five of the latest physical layer authentication algorithms including supervised, semi-supervised, and unsupervised algorithms and deployed them on commercial devices that comply with the WIA-FA standard. We conducted systematic experiments focusing on the motion parameters of devices, the CSI data sampling frequency, the interference caused by worker movement, the surface materials of the devices, and the types of attacks. This study explores the ability of these algorithms to resist attacks and environmental interference in commercial devices and industrial scenarios. Extensive experimental data were collected, and the results indicate that existing authentication algorithms still need improvement to meet the requirements of industrial applications. The experiment findings and the summarized application challenges of these algorithms provide significant guidance for future research and practical industrial implementations. © 1986-2012 IEEE.

关键词： Authentication

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Modelling and experimental investigation of micro-dimpled structures milling with spiral trajectory tool reciprocating motion

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Chinese Journal of Aeronautics 2025年第2期 581-600页

作者： Guangzhou WANG Linjie ZHAO Qi LIU Xiguang LI Yazhou SUN Mingjun CHEN School of Mechatronics Engineering Harbin Institute of Technology Centre for Precision Manufacturing DMEMUniversity of Strathclyde State Key Laboratory of Robotics and System Harbin Institute of Technology

To mill fine and well-defined micro-dimpled structures, a machining manner of spiral trajectory tool reciprocating motion, where the tool repeats the process of ‘feed milling±retract±cutting feed±feed milling again' along the spiral trajectory, was proposed. From the kinematics analysis, it is found that the machining quality of micro-dimpled structures is highly dependent on the machining trajectory using spiral trajectory tool reciprocating motion. To reveal this causation, simulation modelling and experimental studies were carried out. A simulation model was developed to quantitatively and qualitatively investigate the influence of the trajectory discretization strategies(constant-angle and constant-arc length) and parameters(discrete angle, discrete arc length, and pitch) on surface texture and residual height of micro-dimpled structures. Subsequently, microdimpled structures were milled under different trajectory discretization strategies and parameters with spiral trajectory tool reciprocating motion. A comprehensive comparison between the milled results and simulation analysis was made based on geometry accuracy, surface morphology and surface roughness of milled dimples. Meanwhile, the errors and factors affecting the above three aspects were analyzed. The results demonstrate both the feasibility of the established simulation model and the machining capability of this machining way in milling high-quality micro-dimpled structures. Spiral trajectory tool reciprocating motion provides a new machining way for milling micro-dimpled structures and micro-dimpled functional surfaces. And an appropriate machining trajectory can be generated based on the optimized trajectory parameters, thus contributing to the improvement of machining quality and efficiency.

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17β-Trenbolone modulates anxiety-related synaptic plasticity by affecting the interaction between hippocampal TACR3 and systemic testosterone in male mice

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Environmental Research 2025年第Pt 1期279卷 121796页

作者： Zuo, Xiang Bai, Huijuan Qiu, Jinyu Li, Ruimin Kuang, Xiaochen Zhao, Yudi Tuo, Jingyi Zhao, Qili Zhao, Xin Feng, Xizeng College of Life Science State Key Laboratory of Medicinal Chemical Biology Key Laboratory of Bioactive Materials Ministry of Education Nankai University Tianjin300071 China Institute of Robotics & Automatic Information System College of Artificial Intelligence Nankai University Tianjin300071 China

Anxiety Disorder is a common neurological disorder for which ubiquitous environmental endocrine disruptors may be risk factors. 17β-trenbolone (17-TB) has been recognized as a potential environmental endocrine disruptor and its neurotoxic effects have attracted attention. Tachykinin receptor 3 (TACR3), a G protein-coupled receptor involved in pubertal anxiety, and its underlying neural mechanisms remain enigmatic. Therefore, this study investigated the possible relationship between 17-TB and TACR3, testosterone (T), and synaptic plasticity. Our results showed that adolescent male Balb/c mice developed significant anxiety-like behavior after four weeks of exposure to environmentally relevant concentrations of 17-TB (100 μg/kg/day). Transcriptomic RNA-Seq results showed that 17-TB affected abnormal synaptic transmission signals in the hippocampus. Electrophysiological results showed that 17-TB reduced the activity of hippocampal dentate gyrus (DG) neurons and led to the downregulation of hippocampal TACR3 and T levels. In addition, Western blot, immunohistochemistry, ELISA, and qRT-PCR showed that 17-TB exposure led to the downregulation of key hippocampal synaptic proteins PSD95, Gephyrin, and Syn, and induced a metabolic imbalance in glutamate (Glu)/GABA signaling, affecting dopamine signaling. Interestingly, testosterone supplementation (10 mg/kg/day) was effective in ameliorating the above phenomena and alleviating anxiety-like behaviors. These results suggest that 17-TB modulates anxiety-related synaptic plasticity by regulating hippocampal TACR3 and T interactions in vivo. In conclusion, our study contributes to understanding the neurobehavioral and potential mechanistic effects of environmental 17-TB exposure in mammals. It alerts the public to the health risks of chemicals to mammals and suggests new research directions and potential therapeutic targets. © 2025 Elsevier Inc.

关键词： Endocrinology

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