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Understanding the Machining Process of Hierarchical Micro/Nanograting Structures Used for Optical Variable Device

Chinese Journal of Mechanical engineering 2025年第1期38卷 161-185页

作者： Yanquan Geng Wenhan Zhu Xiaosong Zhang Aoxiang Zhang Yongda Yan Hailong Cui Bo Xue Jiqiang Wang TState Key Laboratory of Robotics and Systems Robotics InstituteHarbin Institute of TechnologyHarbin 150080China Sichuan Precision and Ultra-Precision Machining Engineering Technology Center Chengdu 610200China College of Mechanical and Electrical Engineering Northeast Forestry UniversityHarbin 150040China

Hierarchical micro/nanograting structures have attracted increasing attention owing to their significant applications in the fields of structural coloring,anti-counterfeiting,and ***,the fabrication of hierarchical micro/nanograting structures is important for these *** this study,a strategy for machining hierarchical micro/nanograting structures is developed by controlling the tool movement trajectory.A coupling Euler-Lagrange finite element model is established to simulate the machining *** effect of the machining methods on the nanograting formation is demonstrated,and a suitable machining method for reducing the cutting force is *** height of the nanograting decreases with an increase in the tool edge ***,optical variable devices(OVDs)are machined using an array overlap machining *** schemes for the parallel column unit crossover and column unit in the groove crossover are designed to achieve high-quality machining of *** coloring of the logo of the Harbin Institute of technology and the logo of the centennial anniversary of the Harbin Institute of technology on the surface of metal samples,such as aluminum alloys,is *** findings of this study provide a method for the fabrication of hierarchical micro/nanograting structures that can be used to prepare OVDs.

关键词： Hierarchical micro/nanograting structures Optical variable devices Finite element simulation Tool trajectory controlling

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Towards understanding the surface rippling process by periodic reciprocal nanoscratching

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Friction 2023年第10期11卷 1815-1828页

作者： Zihan LI Yongda YAN Jiqiang WANG Chen LI Yanquan GENG State Key Laboratory of Robotics and Systems Robotics InstituteHarbin Institute of TechnologyHarbin 150080China Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

The bundle structure formed perpendicular to the scratching direction is a type of wear-induced structure for *** this study,the formation mechanism of bundle structures on polycarbonate(PC)surfaces is investigated by reciprocal scratching *** on the analysis of the morphologies,friction forces,and height signals,the formation of the bundle structure is *** influence of scratching parameters,including the feed value and scratching direction,on the formation of the bundle structure is also *** is found that the bundle structure is accumulated by the continuous stacking of the sample materials plowed by the tip in stick–slip motion,and that the stick–slip behavior is enhanced with increased scratching *** work reproduces the formation process of bundle structure in experiments for the first time and demonstrates that the stick–slip enhancement mechanism exists in the reciprocal scratching process,providing further insight into the friction behavior of polymers.

关键词： atomic force microscopy(AFM) bundle structures stick-slip friction force

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Method to improve the classification accuracy by in situ laser cleaning of painted metal scraps during laser-induced breakdown spectroscopy based sorting

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Plasma Science and technology 2025年第3期27卷 72-86页

作者： Jaepil LEE Sungho SHIN Inseok JANG Seongguk BAE Sungho JEONG School of Mechanical and Robotics Engineering Gwangju Institute of Science and Technology123 Cheomdangwagi-roBuk-guGwangju 61005Republic of Korea

Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based *** this study,the effects of paint layers on metal surfaces during LIBS classification were *** spectra were collected from metal surfaces painted with black and white paints by ablation with a nanosecond pulsed laser(wavelength=1064 nm,pulse width=7 ns).For the black-painted samples,the LIBS spectra showed a broad background emission,emission lines unrelated to the target metals,large shot-to-shot variation,and a relatively low signal intensity of the target metal,causing poor classification accuracy even at high shot *** the black paint layer by ablating over a wide area prior to LIBS analysis resulted in high classification accuracy with fewer shot numbers.A method to determine the number of cleaning shots necessary to obtain high classification accuracy and high throughput is proposed on the basis of the change in LIBS signal intensity during cleaning *** the white-painted samples,the paint peeled off the metal surface after the first shot,and strong LIBS signals were measured after the following shot,which were attributed to the nanoparticles generated by the ablation of the paint,allowing an accurate classification after only two *** results demonstrate that different approaches must be employed depending on the paint color to achieve high classification accuracy with fewer shot numbers.

关键词： laser induced breakdown spectroscopy(LIBS) scrap metal paint surface contaminant cleaning

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Hemispherical resonator with low subsurface damage machined by small ball-end fine diamond grinding wheel:A novel grinding technique

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Chinese Journal of Aeronautics 2024年第5期37卷 570-585页

作者： Biao QIN Henan LIU Jian CHENG Jinchuan TIAN Jiangang SUN Zihan ZHOU Chuanzhen MA Mingjun CHEN State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

As for the ultra-precision grinding of the hemispherical fused silica resonator,due to the hard and brittle nature of fused silica,subsurface damage(SSD)is easily generated,which enormously influences the performance of such ***,ultra-precision grinding experiments are carried out to investigate the surface/subsurface quality of the hemispherical resonator machined by the small ball-end fine diamond grinding *** influence of grinding parameters on the surface roughness(SR)and SSD depth of fused silica samples is then *** experimental results indicate that the SR and SSD depth decreased with the increase of grinding speed and the decrease of feed rate and grinding *** addition,based on the material strain rate and the maximum undeformed chip thickness,the effect of grinding parameters on the subsurface damage mechanism of fused silica samples is ***,a multi-step ultra-precision grinding technique of the hemispherical resonator is proposed based on the interaction influence between grinding depth and feed ***,the hemispherical resonator is processed by the proposed grinding technique,and the SR is improved from 454.328 nm to 110.449 nm while the SSD depth is reduced by 94%from 40μm to 2.379μ*** multi-step grinding technique proposed in this paper can guide the fabrication of the hemispherical resonator.

关键词： Fused silica Ultra-precision grinding Hemispherical resonator Subsurface damage Grinding technique

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Continuous sign language recognition using intra-inter gloss attention

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Multimedia Tools and Applications 2025年 1-19页

作者： Ranjbar, Hossein Taheri, Alireza Social and Cognitive Robotics Lab. Mechanical Engineering Department Sharif University of Technology Tehran Iran

Many continuous sign language recognition (CSLR) studies adopt transformer-based architectures for sequence modeling due to their powerful capacity for capturing global contexts. Nevertheless, vanilla self-attention, which serves as the core module of the transformer, performs context-aware weighted aggregation over all time steps. Therefore, the local temporal semantics of sign videos may not be fully exploited. This study introduces a novel module for sign language recognition, the intra-inter gloss attention module, designed to leverage relationships among frames within glosses and to capture the semantic and grammatical dependencies between glosses in the video. In the intra-gloss attention module, the video is divided into equally sized chunks, and a self-attention mechanism is applied within each chunk. This localized self-attention significantly reduces complexity and eliminates noise introduced by considering non-relative frames, and achieves a 0.6 improvement in WER based on the baseline model while increasing inference speed by 20%. In the inter-gloss attention module, the chunk-level features within each gloss chunk are initially aggregated by average pooling along the temporal dimension, which leads to a 0.7 improvement in WER. Subsequently, multi-head self-attention is applied to all chunk-level features. Given the non-significance of the signer-environment interaction, we utilize segmentation module to remove the background of the videos. This enables the proposed model to direct its focus toward the signer and achieve an additional 1.5 improvement in WER. Experimental results on the PHOENIX-2014 benchmark dataset demonstrate that our method can effectively extract sign language features in an end-to-end manner without any prior knowledge, improve the accuracy of CSLR, and achieve the word error rate (WER) of 20.4 on the test set which is a competitive result compare to the state-of-the-art which uses additional supervisions. © The Author(s), under exc

关键词： Semantics

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Hybrid Robotic Arm for Autonomous Aerial Refueling

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Chinese Journal of Mechanical engineering 2024年第6期37卷 429-440页

作者： Kaixuan Li Gangfeng Liu Yongsheng Gao Jie Zhao State Key Laboratory of Robotics and Systems Harbin Institute of TechnologyHarbin 150080China School of Mechatronics Engineering Harbin 150080China

Autonomous aerial refueling technology is gaining increasing attention to enhance aircraft combat *** research on autonomous refueling focuses mainly on flight control laws,with little attention to the automation of refueling *** leads to high demands on control law performance and navigation accuracy,making it difficult to ensure *** address this,we propose a robotic arm system capable of automatic docking during the flexible aerial refueling *** system uses a conical kinematic space configuration,offering enhanced stability and impact *** frame-type structure achieves a lightweight ***,we establish a single-objective optimization model for the connecting rod dimensions and apply a genetic algorithm(GA)for their *** also propose a trajectory-fitting calibration theory based on the robotic arm's special configuration and complete its movement accuracy calibration using a laser *** calibration method reduces the robotic arm's motion error by 71%,achieving an absolute positioning accuracy better than 3.5 mm,which meets the requirements for autonomous aerial *** summary,this research presents a hybrid robotic arm that meets automatic docking requirements,offering a new approach to autonomous aerial refueling.

关键词： Autonomous aerial refueling Conical kinematic space configuration Optimization of structural design Calibration method

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Mechanism of material removal and chip formation of alumina dispersion strengthened copper in micro-milling

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Frontiers of Mechanical engineering 2025年第1期20卷 27-43页

作者： Chang LIU Chunya WU Xiguang LI Bo HOU Jiahao WU Ruijiang SUN Mingjun CHEN School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

Alumina dispersion-strengthened copper (ADSC), as a representative particle-reinforced metal matrix composite (PRMMC), exhibits superior wear resistance and high strength. However, challenges arise in their processability because of the non-uniform material properties of biphasic materials. In particular, limited research has been conducted on the reinforcement mechanism and behavior of particles during material cutting deformation of PRMMC with nanoscale particles. In this study, a cutting simulation model for ADSC was established, separating the nanoscale reinforcement particles from the matrix. This model was utilized to analyze the interactions among particles, matrix, and tool during the cutting process, providing insights into chip formation and fracture. Particles with high strength and hardness are more prone to storing stress concentrations, anchoring themselves at grain boundaries to resist grain fibration, thereby influencing the stress distribution in the cutting deformation zone. Stress concentration around the particles leads to the formation of discontinuous chips, indicating that ADSC with high-volume fractions of particle (VFP) exhibits low cutting continuity, which is consistent with the results of cutting experiments. The tool tip that is in contact with particles experiences stress concentration, thereby accelerating tool wear. Cutting ADSC with 1.1% VFP results in tool blunting, which increases the radius of cutting edge from 0.5 to 1.9 μm, accompanied with remarkable coating delamination and wear. Simulation results indicate that the minimum uncut chip thickness increases from 0.04 to 0.07 μm as VFP increases from 0.3% to 1.1%. In conjunction with scratch experiments, MUCT increases with the augmentation of VFP. Computational analysis of the specific cutting force indicates that particles contribute to the material’s size effect. The results of this study provide theoretical guidance for practical engineering machining of ADSC, indicating its g

关键词： alumina dispersion-strengthened copper particle-reinforced metal matrix composites material removal mechanism micro-milling chip formation minimum uncut chip thickness

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Teleoperation with automatic posture regulation and broad learning control for assembly tasks

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Science China(Information Sciences) 2024年第11期67卷 359-360页

作者： Liwen SITU Zhenyu LU Chenguang YANG School of Automation Science and Engineering South China University of Technology Bristol Robotics Laboratory University of the West of England

In recent years, robot teleoperation systems have been widely used in assembly tasks due to their ability to combine human control with robotic execution, addressing limitations in precision, perception, and intelligence faced by fully automated robots. However, robot teleoperation for assembly tasks still encounters several challenges. In complex and unstructured environments, telerobots must regulate the posture of their manipulators to avoid obstacles and singularities, ensuring the safety of human operators [1].

关键词： Remote control

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Simultaneously improving fabrication accuracy and interfacial bonding strength of multi-material projection stereolithography by multi-step exposure

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International Journal of Smart and Nano Materials 2024年第2期15卷 387-404页

作者： Xinghong Deng Guangyu Zhang Yi Mo Zhiyuan Huang Dekai Zhou Jing Qiao Longqiu Li State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbinChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbinChina

Multi-material additive manufacturing(MMAM)takes full advantage of the ability to arbitrarily place materials of addi-tive manufacturing technology,enabling immense design free-dom and functional print *** MMAM technologies,projection stereolithography(PSL)exhibits a great balance of high resolution and fast printing ***,fabrication accuracy of multi-material PSL is hin-dered by large overcure used to strengthen interfacial bond-ing weakened by chemical affinity and material-exchange *** present a novel multi-step exposure method for multi-material PSL process to overcome this ***,the whole layer is moderately exposed producing over-cure of single-material PSL level to generate *** weakened interfaces are strengthened individually with addi-tional steps of *** multi-step exposure is integrated into the already efficient materials printing order of multi-material PSL *** depth and overcure of photocur-able resins are modeled and *** required to achieve sufficient interfacial bonding of single-material interfaces built through material-exchange process and multi-material interfaces with altering materials printing order is determined with tensile *** channels are used to compare fabrication accuracy of traditional single-step exposure and our multi-step exposure *** method can be widely applied in multi-material PSL to improve fabri-cation accuracy in a variety of applications including micro-fluidic devices.

关键词： Additive manufacturing multi-material projection stereolithography multi-step exposure interfacial bonding

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Design and Analysis of a Novel Sch?nflies Motion Parallel Robot with Full Cycle Rotation

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Chinese Journal of Mechanical engineering 2024年第6期37卷 441-455页

作者： Luquan Li Yuefa Fang Lin Wang Jiaqiang Yao Institute of AI and Robotics Academy for Engineering and TechnologyFudan UniversityShanghai 200433China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Due to the complex structures of multi-limbed parallel robots,conventional parallel robots generally have limited workspace,complex kinematics,and complex dynamics,which increases the application difficulty of parallel robot in industrial *** solve the above problems,this paper proposes a single-loop Sch?nflies motion parallel robot with full cycle rotation,the robot can generate Sch?nflies motion by the most simplified *** novel Sch?nflies motion parallel robot is a two-limb parallel mechanism with least links and joints,and each limb is driven by a 2-degree of freedom(DOF)cylindrical driver(C-driver).The full cycle rotation of the output link is achieved by“…R-H…”structure,where the revolute(R)and helical(H)joints are ***,kinematics,workspace and singularity analysis of the novel Sch?nflies motion parallel robot are ***,dynamic model is formulated based on the principle of virtual ***,a pick-and-place task is implemented by the proposed Sch?nflies motion parallel robot and a serial SCARA robot,*** simulation results verify the correctness of the theoretical ***,dynamics performances of the proposed Sch?nflies motion parallel robot and a serial SCARA robot are compared,which reveal the performance merits of the proposed Sch?nflies motion parallel robot.

关键词： Single-loop parallel robot Schönflies motion Virtual work principle Dynamics

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