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Experiments on the relationship between the structural parameters of contraposition transducers and the acoustic levitation transportation trajectory

Experiments on the relationship between the structural param...

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2019 International Congress on Ultrasonics, ICU 2019

作者： Dong, Huijuan Sui, Mingyang Mao, Chuncheng Mu, Guanyu Zhao, Jie School of Mechatronics Engineering Harbin Institute of Technology Hei Longjiang Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China

ISBN: (纸本)9781665407090

Standing wave acoustic levitation transportation technique has been widely used in many research areas. In this work, two Langevin-type piezoelectric transducers' central lines are mounted at a certain angle which is named a contraposition transducer array. The levitator developed in this work is constructed using the array and a reflector. Accordingly, a standing wave acoustic field is formed to levitate and transport particles by optimizing the angle between central lines of the two transducers, the distance between the two transducers' output and their reflectors, the exciting phase differential on the two transducers. In this standing wave acoustic field, the trapped objects can be levitated and transported by modulating the exciting phase difference of the two transducers. In this work, the locations of the levitated particles are acquired by a high speed video camera and are clarified using the Hough Circle algorithm. The experiments carried out by the authors have demonstrated the effects of the levitator's structure parameters (including the angle between central lines of the two transducers, the distance between the two transducers' output and the reflector) on the transportation trajectory. © 2020 Acoustical Society of America.

关键词： Video cameras

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Anisotropy of thermal transport in phosphorene: A comparative first-principles study using different exchange-correlation functional

arXiv

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arXiv 2021年

作者： Zhang, Fa Zheng, Xiong Wang, Huimin Ding, Liang Qin, Guangzhao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China

Phosphorene, as a new type of two-dimensional (2D) semiconductor material, possesses unique physical and chemical properties, and thus has attracted widespread attention in recent years. With its increasing applications in nano/optoelectronics and thermoelectrics, a comprehensive study on its thermal transport properties is necessary. It has been concluded from previous studies that there exist vast difference and uncertainty in the theoretically predicted thermal conductivity, which is generally attributed to the selection of XC functional. However, there is no comprehensive investigation on this issue. In this paper, based on first-principles calculations using 12 different exchange-correlation (XC) functionals, the phonon transport properties of phosphorene are systematically studied by solving the Boltzmann transport equation (BTE). The results show noticeable differences in the phonon transport properties of phosphorene under different XC functionals. For instance, the thermal conductivity of phosphorene along the zigzag direction ranges from 0.51 to 30.48 Wm−1K-1, and that along the armchair direction ranges from 0.15 to 5.24 Wm−1K−1. Moreover, the anisotropy of thermal conductivity is between 3.4 and 6.9, which is fundamentally originated from the special hinge-like structure. This study conducts an in-depth analysis of phonon transport to reveal the effect and mechanism of different XC functionals for predicting thermal transport properties, which would provide a reference for future research on phosphorene and other novel materials. © 2021, CC BY.

关键词： Anisotropy

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Aeroengine remaining useful life prediction via integrating enhanced inverted transformer and spatiotemporal graph learning

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ISA Transactions 2025年

作者： Sun, Shilong Ding, Hao Zhao, Zida Zhou, Yu Wang, Dong Xu, Wenfu School of Robotics and Advanced Manufacturing College of Artificial Intelligence Harbin Institute of Technology Shenzhen China Guangdong Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics Shenzhen China College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China

Accurate prediction of aeroengine Remaining Useful Life (RUL) is critical for ensuring flight safety, minimizing maintenance costs, and improving operational efficiency. This study proposes a novel model, the Fourier-Enhanced Inverted Transformer with Graph-Augmented Spatiotemporal Modeling (FIT-GSTM), to enhance RUL prediction performance. FIT-GSTM combines an inverted Transformer with a Spatiotemporal Graph Convolutional Network (STGCN) to effectively capture global spatiotemporal dependencies across multi-sensor data. To further enrich feature representation, the model incorporates Fast Fourier Transform (FFT) to extract frequency-domain information and fuses it with time-domain features, enhancing robustness to noise. Additionally, the integration of Memory Tokens and Reversible Instance Normalization (RevIN) strengthens the model's ability to retain long-term dependencies and adapt to heterogeneous data distributions. Experimental evaluations on the C-MAPSS dataset demonstrate that FIT-GSTM achieves superior RUL prediction accuracy and generalization compared to existing methods, highlighting its potential for real-world deployment in aeroengine health management. © 2025 ISA

关键词： Fast Fourier transforms

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Overcoming Van der Waals Forces in reconfigurable nanostructures

arXiv

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arXiv 2022年

作者： Zhang, Wang Wang, Hao Tan, Alvin T.L. Ranganath, Anupama Sargur Zhang, Biao Wang, Hongtao Chan, John You En Ruan, Qifeng Liu, Hailong Ha, Son Tung Wang, Dong Ravikumar, Venkat K. Low, Hong Yee Yang, Joel K.W. Engineering Product Development Singapore University of Technology and Design Singapore487372 Singapore Northwestern Polytechnical University 127 West Youyi Road Xi'An710072 China Institute of Materials Research and Engineering Singapore138634 Singapore Robotics Institute State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China Advanced Micro Devices Singapore Pte Ltd Singapore Singapore

Reconfigurable metamaterials1-3 require constituent nanostructures to demonstrate switching of shapes with external stimuli. For generality, such nanostructures would touch and stick to other surfaces in one of its configurations. Yet, a longstanding challenge is in overcoming this stiction caused by Van der Waals forces, which impedes shape recovery. Here, we introduce a stiff yet self-recovering material system based on acrylic acid, and tested it in high-aspect ratio structures, where recovery is weak. This designer material has a storage modulus of ~5.2 GPa at room temperature and ~90 MPa in the rubbery state at 150 ℃, an order of magnitude higher than previous reports. A high-resolution resin for two-photon lithography was developed based on this polymer system, enabling 3D printing of nanopillars with diameters of ~400 nm and aspect ratio as high as ~10. Experimentally, we observed self-recovery as collapsed and touching structures overcome stiction to stand back up. We developed a theoretical model to explain the recoverability of these sub-micron structures. Reconfigurable structural colour prints and holograms were demonstrated, indicating potential applications of the material system as a shape memory polymer suitable for sub-micron reconfigurable metamaterials. Copyright © 2022, The Authors. All rights reserved.

关键词： Van der Waals forces

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Closed-Form Modeling and Analysis of an XY Flexure-Based Nano-Manipulator

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Chinese Journal of Mechanical engineering 2018年第1期31卷 176-186页

作者： Yan-Ding Qin Xin Zhao Bijan Shirinzadeh Yan-Ling Tian Da-Wei Zhang Institute of Robotics and Automatic Information System (Tianjin Key Laboratory of Intelligent Robotics) Nankai University Robotics and Mechatronics Research Laboratory Department of Mechanical and Aerospace Engineering Monash University School of Mechanical Engineering Tianjin University

Flexure-based mechanisms are widely utilized in nano manipulations. The closed-form statics and dynamics modeling is difficult due to the complex topologies, the inevitable compliance of levers, the Hertzian contact interface, etc. This paper presents the closed-form modeling of an XY nano-manipulator consisting of statically indeterminate symmetric(SIS) structures using leaf and circular flexure hinges. Theoretical analysis reveals that the lever’s compliance, the contact stiffness, and the load mass have significant influence on the static and dynamic performances of the *** are conducted to verify the effectiveness of the established models. If no piezoelectric actuator(PEA) is installed, the influence of the contact stiffness can be eliminated. Experimental results show that the estimation error on the output stiffness and first natural frequency can reach 2% and 1.7%, respectively. If PEAs are installed, the contact stiffness shows up in the models. As no effective method is currently available to measure or estimate the contact stiffness, it is impossible to precisely estimate the performance of the overall system. In this case, the established closed-form models can be utilized to calculate the bounds of the performance. The established closed-form models are widely applicable in the design and optimization of planar flexure-based mechanisms.

关键词： Flexure-based mechanism Statically indeterminate structure Dynamics Lever mechanism Piezoelectric actuator

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Influence of manufacturing errors of bearing components on rotational accuracy of cylindrical roller bearings

Research Square

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Research Square 2021年

作者： Yu, Yongjian Li, Jishun Xue, Yujun School of Mechatronics Engineering Henan University of Science and Technology Luoyang471003 China Henan Key Laboratory for Machinery Design and Transmission System Henan University of Science and Technology Luoyang471003 China Luoyang LYC Bearings Co. Ltd State Key Laboratory of Aviation Precision Bearings Luoyang471039 China

Understanding the influence of bearing component manufacturing errors and roller number on the rotational accuracy of rolling bearings is crucial in the design of high precision bearings. The rotational accuracy of an assembled bearing is dependent upon roller number and manufacturing error of the bearing components. We propose a model for calculating the rotational accuracy of a cylindrical roller bearing;we experimentally verified the effectiveness of the model in predicting the radial run-out of the inner ring proposed in the previous paper in this series. We sought to define the key contributing factors to the rotational accuracy by studying both the influence of the coupling effect of the roller number and the influence of the manufacturing errors in the inner raceway, outer raceway, and rollers on the motion error. The model and results will help engineers choose reasonable manufacturing tolerances for bearing components to achieve the required rotational accuracy. © 2021, CC BY.

关键词： Rollers (machine components)

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The energy-saving advantages of burst-and-glide mode for thunniform swimming

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Journal of Hydrodynamics 2018年第6期30卷 1072-1082页

作者： Dan Xia Wei-shan Chen Jun-kao Liu Xiang Luo School of Mechanical Engineering Southeast University State Key Laboratory of Robotics and System Harbin Institute of Technology

This paper explores the energy-saving advantages of the burst-and-glide swimming and compares it with the normal self-swimming for a thunniform swimmer. The virtual swimmer allows us to perform controlled numerical experiments by varying the swinging tail number and the duty cycle while keeping the other parameters fixed. 3-D Navier-Stokes equations are used to compute the viscous flow over the swimmer. The user-defined functions and the dynamic mesh technology are used to simulate the burst-and-glide swimming. The results show that with the increase of the swinging tail number or the duty cycle, the swimming velocity, the power and the efficiency all increase, but the velocity-power ratio decreases somewhat. Therefore, choosing smaller swinging tail number and duty cycle is beneficial in reducing the power and increasing the velocity-power ratio, and thus to obtain the same velocity, less power is consumed. And to swim the same distance, the energy can significantly be saved. The power consumption, the efficiency and the velocity-power ratio in the burst-and-glide case are 43.9%, 40.6% and 1.15 times of those in the normal swimming case, respectively. The flow structures clearly show the evolution process around the fish in the burst-and-glide swimming. The findings can be used to reasonably plan the swimming action and to take the advantage of the external flow field energy for the fishlike robot, to be more efficient and energy-saving.

关键词： Energy-saving advantages burst-and-glide mode normal self-swimming thunniform swimmer

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Object-oriented Map Exploration and Construction Based on Auxiliary Task Aided DRL

Object-oriented Map Exploration and Construction Based on Au...

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International Conference on Pattern Recognition

作者： Junzhe Xu Jianhua Zhang Shengyong Chen Honghai Liu College of Computer Science and Technology Zhejiang University of Technology Hangzhou China College of Computer Science and Technology Tianjin University of Technology Tianjin China State Key Laboratory of Robotics and System School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen China

Environment exploration by autonomous robots through deep reinforcement learning (DRL) based methods has attracted more and more attention. However, existing methods usually focus on robot navigation to single or multiple fixed goals, while ignoring the perception and construction of external environments. In this paper, we propose a novel environment exploration task based on DRL, which requires a robot fast and completely perceives all objects of interest, and reconstructs their poses in a global environment map, as much as the robot can do. To this end, we design an auxiliary task aided DRL model, which is integrated with the auxiliary object detection and 6-DoF pose estimation components. The outcome of auxiliary tasks can improve the learning speed and robustness of DRL, as well as the accuracy of object pose estimation. Comprehensive experimental results on the indoor simulation platform AI2-THOR have shown the effectiveness and robustness of our method.

关键词： Navigation Object oriented modeling Pose estimation Semantics Object detection Reinforcement learning Robustness

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Review of surgical robotic systems for keyhole and endoscopic procedures:state of the art and perspectives

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Frontiers of Medicine 2020年第4期14卷 382-403页

作者： Yuyang Chen Shu’an Zhang Zhonghao Wu Bo Yang Qingquan Luo Kai Xu State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China RII Lab(Lab of Robotics Innovation and Intervention) UM-SJTU Joint InstituteShanghai Jiao Tong UniversityShanghai 200240China Department of Urology Shanghai Changhai Hospitalthe Second Military Medical UniversityShanghai 200433China Shanghai Lung Cancer Center Shanghai Chest HospitalShanghai Jiao Tong UniversityShanghai 200030China

Minimally invasive surgery,including laparoscopic and thoracoscopic procedures,benefits patients in terms of improved postoperative outcomes and short recovery *** challenges in hand–eye coordination and manipulation dexterity during the aforementioned procedures have inspired an enormous wave of developments on surgical robotic systems to assist keyhole and endoscopic procedures in the past *** paper presents a systematic review of the state-of-the-art systems,picturing a detailed landscape of the system configurations,actuation schemes,and control approaches of the existing surgical robotic systems for keyhole and endoscopic *** development challenges and future perspectives are discussed in depth to point out the need for new enabling technologies and inspire future researches.

关键词： surgical robots keyhole surgery endoscopic surgery

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Time-Optimal Control of Underactuated Wheeled Inverted Pendulum Vehicles Along Specified Paths

Time-Optimal Control of Underactuated Wheeled Inverted Pendu...

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International Conference on Advanced robotics and mechatronics (ICARM)

作者： Yigao Ning Ming Yue Zenan Lin School of Automotive Engineering Dalian University of Technology Dalian China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

ISBN: (数字)9781728164793

ISBN: (纸本)9781728164809

This study proposes a time-optimal control method for a wheeled inverted pendulum (WIP) vehicle under specified paths. Firstly, the given path is described with a parametric form, and the kinematic model, velocity constraint and acceleration constraint are all parameterized with a same parameter as the geometric path. Meanwhile, the stabilization constraint of vehicle body is also formulated through the kinematic coupling relationship to take the underactuated characteristic into full consideration. Next, the time-optimal trajectory is constructed by a sequence of minimum acceleration and maximum acceleration trajectories based on phase-plane analysis, and the optimality is illustrated through rigorous analysis. Finally, a time-optimal trajectory tracking controller is designed for the WIP vehicle to realize the minimum-time motion, and numerical simulation results validate the effectiveness of the proposed method.

关键词： Acceleration Trajectory mechatronics Kinematics Mobile robots Trajectory tracking

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