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arXiv 2022年

作者： Li, Qi Shen, Ziyi Li, Qian Barratt, Dean C. Dowrick, Thomas Clarkson, Matthew J. Vercauteren, Tom Hu, Yipeng Centre for Medical Image Computing Wellcome/EPSRC Centre for Interventional and Surgical Sciences Department of Medical Physics and Biomedical Engineering University College London London United Kingdom State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Biomedical Engineering & Imaging Sciences King’s College London London United Kingdom

Three-dimensional (3D) freehand ultrasound (US) reconstruction without a tracker can be advantageous over its two-dimensional or tracked counterparts in many clinical applications. In this paper, we propose to estimate 3D spatial transformation between US frames from both past and future 2D images, using feed-forward and recurrent neural networks (RNNs). With the temporally available frames, a further multitask learning algorithm is proposed to utilise a large number of auxiliary transformation-predicting tasks between them. Using more than 40,000 US frames acquired from 228 scans on 38 forearms of 19 volunteers in a volunteer study, the hold-out test performance is quantified by frame prediction accuracy, volume reconstruction overlap, accumulated tracking error and final drift, based on ground-truth from an optical tracker. The results show the importance of modelling the temporal-spatially correlated input frames as well as output transformations, with further improvement owing to additional past and/or future frames. The best performing model was associated with predicting transformation between moderately-spaced frames, with an interval of less than ten frames at 20 frames per second (fps). Little benefit was observed by adding frames more than one second away from the predicted transformation, with or without LSTM-based RNNs. Interestingly, with the proposed approach, explicit within-sequence loss that encourages consistency in composing transformations or minimises accumulated error may no longer be required. The implementation code and volunteer data1 will be made publicly available ensuring reproducibility and further research. © 2022, CC BY.

关键词： Ultrasonics

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Controlled Propulsion of Asymmetric Janus Microdimer Swimmers under Rotating Magnetic Fields

Controlled Propulsion of Asymmetric Janus Microdimer Swimmer...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Shimin Yu Tianlong Li Shaopeng Wu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Harbin Institute of Technology Harbin China

ISBN: (数字)9781728151694

ISBN: (纸本)9781728151700

Untethered micro-/nanorobots at low Reynolds numbers present significant potential in biomedical applications as result of their enhanced power, remote actuation, and versatility. Herein, a highly efficient asymmetric Janus microdimer swimmer propelled by a rotating uniform magnetic field was investigated experimentally. The asymmetric microdimers can achieve speed of 98 μm·s -1 at 20 Hz and 5 mT. Besides, the controllable and flexible motility performance of microdimer motors can be easily obtained by adjusting the magnetic field. Such an asymmetric Janus microdimer swimmer is highly promising in a variety of realistic micro-/nanoscale scenarios.

关键词： Industrial electronics Navigation Conferences Propulsion Nanoscale devices Trajectory Magnetic fields

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Locomotion Stability Analysis of Lower Extremity Augmentation Device

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Journal of Bionic Engineering 2019年第1期16卷 99-114页

作者： Likun Wang Chaofeng Chen Wei Dong Zhijiang Du Yi Shen Guangyu Zhao State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Astronautics Harbin Institute of TechnologyHarbin 150001China Weapon Equipment Research Institute China Ordnance Industries GroupBeijing 102202China

Stability is of great significance in the theoretical framework of biped ***-time control and walking patterns planning are on the premise that the robot works in the stable *** this paper,we address the crucial issue of the locomotion stability based on the modified Poincare return map and the hybrid *** akin to the traditional stability criteria,i.e.,the Zero Moment Point(ZMP)and the Center of Mass(CoM),the modified Poincare return map is more appropriate for both dynamic walking arid non-periodic ***,a novel high-level reinforcement learning methodology,so-called active PI2 CMA-ES,is proposed in this paper to plan the exoskeleton *** proposed learning methodology demonstrates that the locomotion of the exoskeleton is asymptotically stable according to the modified Poincare return map ***,the proposed learning methodology is tested by the Lower Extremity Augmentation Device(LEAD)and its effectiveness is verified by the experiments.

关键词： biped locomotion dynamic walking Dynamic Movement Primitives (DMP),stability exoskeleton bioinspiration

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Scientific Exploration of Challenging Planetary Analog Environments with a Team of Legged Robots

arXiv

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arXiv 2023年

作者： Arm, Philip Waibel, Gabriel Preisig, Jan Tuna, Turcan Zhou, Ruyi Bickel, Valentin Ligeza, Gabriela Miki, Takahiro Kehl, Florian Kolvenbach, Hendrik Hutter, Marco Robotic Systems Lab ETH Zurich Zurich Switzerland State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Laboratory of Hydraulics Hydrology and Glaciology ETH Zurich Zurich Switzerland Center for Space and Habitability University of Bern Bern Switzerland Department of Environmental Sciences University of Basel Basel Switzerland University of Zurich Dübendorf Switzerland Center for Theoretical Astrophysics and Cosmology University of Zurich Zurich Switzerland Institute of Medical Engineering Space Biology Group Lucerne University of Applied Sciences and Art Hergiswil Switzerland

The interest in exploring planetary bodies for scientific investigation and in-situ resource utilization is ever-rising. Yet, many sites of interest are inaccessible to state-of-the-art planetary exploration robots because of the robots’ inability to traverse steep slopes, unstructured terrain, and loose soil. Additionally, current single-robot approaches only allow a limited exploration speed and a single set of skills. Here, we present a team of legged robots with complementary skills for exploration missions in challenging planetary analog environments. We equipped the robots with an efficient locomotion controller, a mapping pipeline for online and post-mission visualization, instance segmentation to highlight scientific targets, and scientific instruments for remote and in-situ investigation. Furthermore, we integrated a robotic arm on one of the robots to enable high-precision measurements. Legged robots can swiftly navigate representative terrains, such as granular slopes beyond 25 degrees, loose soil, and unstructured terrain, highlighting their advantages compared to wheeled rover systems. We successfully verified the approach in analog deployments at the BeyondGravity ExoMars rover testbed, in a quarry in Switzerland, and at the Space Resources Challenge in Luxembourg. Our results show that a team of legged robots with advanced locomotion, perception, and measurement skills, as well as task-level autonomy, can conduct successful, effective missions in a short time. Our approach enables the scientific exploration of planetary target sites that are currently out of human and robotic reach. Copyright © 2023, The Authors. All rights reserved.

关键词： Robots

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Locally guided multiple Bi-RRT∗ for fast path planning in narrow passages

Locally guided multiple Bi-RRT∗ for fast path planning in n...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Shu, Xin Ni, Fenglei Zhou, Zhou Liu, Yechao Liu, Hong Zou, Tian Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin Heilongjiang Province China Department of System Dynamics Foshan Guangdong Province China

ISBN: (纸本)9781728163215

关键词： Motion planning

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Modeling and Design of Periodic Polygonal Lattices Constructed from Microstructures with Varying Curvatures

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Physical Review Applied 2022年第4期17卷 044032-044032页

作者： Le Dong Dong Wang Jinqiang Wang Chengru Jiang Hui Wang Biao Zhang Mao See Wu Guoying Gu Robotics Institute and State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China Frontiers Science Center for Flexible Electronics (FSCFE) Xi’an Institute of Flexible Electronics (IFE) and Xi’an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University 127 West Youyi Road Xi’an 710072 China School of Mechanical and Aerospace Engineering Nanyang Technological University 50 Nanyang Avenue 639798 Singapore

Lattice structures can exhibit unusual mechanical properties by appropriate design and arrangement of the microstructures, and have already found applications in areas such as tissue engineering, stretchable electronics, and soft robotics. However, the designed microstructures generally follow simple geometric patterns with constant curvatures and theoretical models are developed for each geometry particularly. It lacks a universal method to model and design the periodic lattice constructed from microstructures with varying curvatures. In this paper, we develop a universal approach to design polygonal lattices with a wide range of microstructures with varying curvatures using instant curvature and parametric functions. A finite deformation model is proposed for the microstructures and the corresponding lattices, which considers the wavy or curled microstructure, hierarchical geometry, and large deformation. Experiments and finite-element simulations are conducted to validate the theoretical model. All of Young’s modulus, stretchability, and Poisson’s ratio can be inversely designed using the developed theoretical model. Results show that the stretchability of the highly stretchable lattice can be further increased by more than 4 times using densely curled microstructure. The signs of Poisson’s ratio can also change with the axial strain by rationally designing the microstructures. By combining curve fitting and curvature and parametric functions, the mechanical behaviors of lattices constructed by bioinspired microstructures can also be predicted. The lattice structures are then demonstrated to reinforce a hydrogel with modulus increased by around 2 orders and act as a biomimetic soft-strain sensor. This work could aid the design of a hierarchical lattice and have potential applications in tissue engineering, stretchable electronics, and soft robotics.

关键词： Biomimetic & bio-inspired materials Devices Elastic deformation Flexible electronics Mechanical metamaterials Origami & Kirigami Strain Smart materials

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Practical fractional-order variable-gain super-twisting control with application to wafer stages of photolithography systems

arXiv

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arXiv 2021年

作者： Kuang, Zhian Sun, Liting Gao, Huijun Tomizuka, Masayoshi Research Institute of Intelligent Control and Systems Harbin Institute of Technology Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Mechanical Control System Lab Mechanical Engineering Department University of California BerkeleyCA94720 United States

In this paper, a practical fractional-order variable-gain super-twisting algorithm (PFVSTA) is proposed to improve the tracking performance of wafer stages for semiconductor manufacturing. Based on the sliding mode control (SMC), the proposed PFVSTA enhances the tracking performance from three aspects: 1) alleviating the chattering phenomenon via super-twisting algorithm and a novel fractional-order sliding surface (FSS) design, 2) improving the dynamics of states on the sliding surface with fast response and small overshoots via the designed novel FSS and 3) compensating for disturbances via variable-gain control law. Based on practical conditions, this paper analyzes the stability of the controller and illustrates the theoretical principle to compensate for the uncertainties caused by accelerations. Moreover, numerical simulations prove the effectiveness of the proposed sliding surface and control scheme, and they are in agreement with the theoretical analysis. Finally, practice-based comparative experiments are conducted. The results show that the proposed PFVSTA can achieve much better tracking performance than the conventional methods from various perspectives. Copyright © 2021, The Authors. All rights reserved.

关键词： Sliding mode control

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Long-term Dependency for 3D Reconstruction of Freehand Ultrasound Without External Tracker

arXiv

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arXiv 2023年

作者： Li, Qi Shen, Ziyi Li, Qian Barratt, Dean C. Dowrick, Thomas Clarkson, Matthew J. Vercauteren, Tom Hu, Yipeng The UCL Centre for Medical Image Computing The Wellcome/EPSRC Centre for Interventional and Surgical Sciences Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BT United Kingdom State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Biomedical Engineering & Imaging Sciences King’s College London LondonWC2R 2LS United Kingdom

Objective: Reconstructing freehand ultrasound in 3D without any external tracker has been a longstanding challenge in ultrasound-assisted procedures. We aim to define new ways of parameterising long-term dependencies, and evaluate the performance. Methods: First, long-term dependency is encoded by transformation positions within a frame sequence. This is achieved by combining a sequence model with a multi-transformation prediction. Second, two dependency factors are proposed, anatomical image content and scanning protocol, for contributing towards accurate reconstruction. Each factor is quantified experimentally by reducing respective training variances. Results: 1) The added long-term dependency up to 400 frames at 20 frames per second (fps) indeed improved reconstruction, with an up to 82.4% lowered accumulated error, compared with the baseline performance. The improvement was found to be dependent on sequence length, transformation interval and scanning protocol and, unexpectedly, not on the use of recurrent networks with long-short term modules;2) Decreasing either anatomical or protocol variance in training led to poorer reconstruction accuracy. Interestingly, greater performance was gained from representative protocol patterns, than from representative anatomical features. Conclusion: The proposed algorithm uses hyperparameter tuning to effectively utilise long-term dependency. The proposed dependency factors are of practical significance in collecting diverse training data, regulating scanning protocols and developing efficient networks. Significance: The proposed new methodology with publicly available volunteer data and code1 for parametersing the long-term dependency, experimentally shown to be valid sources of performance improvement, which could potentially lead to better model development and practical optimisation of the reconstruction application. © 2023, CC BY.

关键词： Ultrasonics

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Design and Experimental Validation of Sealing Assembly for Lunar Regolith Volatile Extraction Heating Furnace

Design and Experimental Validation of Sealing Assembly for L...

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IEEE International Conference on robotics and Biomimetics

作者： Hongan Zhang Junyue Tang Yinchao Wang Zixiao Lu Bo Wang Miaoyan Cao Shengyuan Jiang Mechanical Engineering Yanshan University Qinhuangdao P. R. China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin P. R. China Mechatronics Institute Shenyang Aerospace University Shenyang P. R. China National Center for Nanoscience and Technlogy Chinese Academy of Science Beijing P. R. China China Academy of Space Technology Beijing P. R. China

A lunar regolith in-situ analysis payload deploying a mass spectrometer is proposed to exactly detect the water ice of the South Pole of the moon for China future lunar exploration missions. In order to realize the goal, an airtight heating furnace for volatile extraction from lunar regolith is desired. In this paper, sealing methods for lunar regolith volatile in heating furnace to future proposed in-situ sampling and analysis of lunar samples were investigated based on power requirements, furnace closing accuracy requirements, dust tolerance and operation in the Lunar environment. Methods implemented include a balanced metal hollow ring seal, a double channel ferrule tab ring radial seal and a spring energized seal. Comparing the performance of sealing methods under the above conditions, a spring energized seal is selected as the heating furnace seal. The materials and structure of the seal are designed based on the rigidity requirements, leakage rate requirements and working environment requirements. In order to test the sealing performance of seals after repeated sealing in high and low temperature environments, a seal leak detection system was designed. The test results indicate that the seal can meet the sealing performance requirements after repeated sealing at various temperatures.

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Anisotropic tensile properties and high-cycle fatigue behavior of Ti6Al4V fabricated by single and dual laser-powder bed fusion

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Materials Science and Engineering: A 2025年 941卷

作者： Li, Guotai Hu, Peichen Fan, Yuzhan Wu, Ming Chen, Mingjun Yu, Tianyu State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of Education Heilongjiang Harbin150001 China Department of Computer Science KU Leuven Leuven3001 Belgium Department of Mechanical Engineering KU Leuven Leuven3001 Belgium

The development of multi laser-powder bed fusion (PBF) technology has significantly reduced the production time for large engine components. However, the impact of thermal effects and microstructural characteristics in the laser beam overlap region on the anisotropic mechanical behavior of metallic materials remains unclear. This study investigated the anisotropic tensile properties and high-cycle fatigue behavior of Ti6Al4V produced by both single laser-PBF (SL-PBF) and dual laser-PBF (DL-PBF). As-built DL-PBF samples exhibited high strength (1404 MPa) but low ductility (3.6 %). After heat treatment, the samples achieved a strength-ductility balance, with an ultimate tensile strength of 1089 MPa, and an elongation of 17.1 %. The mechanical properties of Ti6Al4V produced by DL-PBF were influenced by the α lath thickness, dislocation density and texture. The precipitation of small-angle grain boundaries during DL-PBF process was found to contribute to the strong anisotropy. Due to the influence of internal pore forming, the fatigue strength of the DL-PBF samples was lower than that of the SL-PBF samples. Pores in the dual-laser beam overlap region accelerated the fatigue crack propagation, resulting in a venation-like pattern. In contrast, cracks in the SL-PBF samples propagated in a circular pattern around internal pore. A high-speed camera was employed to capture the dual-laser beams dynamics during pore formation. This study provides a comprehensive analysis of the mechanical properties and pore formation mechanisms in the DL-PBF process. © 2025 Elsevier B.V.

关键词： Tensile strength

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