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

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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Design of a series elastic actuator with double-layer parallel spring for lower limb exoskeletons

Design of a series elastic actuator with double-layer parall...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Chen, Chaofeng Wu, Dongmei Dong, Wei Du, Zhijiang He, Long Huang, Linxiang Wang, Jiaqi Shi, Yongjun Xu, Guoqiang Si, Fang Xiao, Tiantian Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin Heilongjiang Province China China South Industries Group Corporation Weapon Equipment Research Institute Beijing China

ISBN: (纸本)9781728163215

This paper presents a novel Series Elastic Actuator (SEA) with double-layer parallel spring for lower limb exoskeletons (LLE). The SEA can improve the human-robot interaction comfort and have the ability to absorb shock and vibration. In order to make the assembly process simple and convenient, the series elastic unit adopt split structure, which includes an inner ring structure, an outer ring structure and rectangular springs as elastic element. At the same time, in order to meet the requirements of the stiffness and dimensions of the SEA, a double-layer parallel spring arrangement is adopted. The stiffness of SEA is 312Nm/rad, which is obtained by the stiffness calibration experiment. In the experiments, the SEA is used in the knee joint of LLE and an impedance controller is designed to achieve knee joint tracking motion. Finally, the experiments results show the position tracking performance of the LLE, which illustrates the effectiveness of the SEA. © 2019 IEEE.

关键词： Human robot interaction

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Application of light diffraction theory to qualify the downstream light field modulation property of mitigated KDP crystals

arXiv

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arXiv 2020年

作者： Yang, Hao Cheng, Jian Liu, Zhichao Liu, Qi Zhao, Linjie Tan, Chao Wang, Jian Chen, Mingjun State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Research Center of Laser Fusion China Academy of Engineering Physics Mianyang621900 China

Micro-milling can effectively remove laser damage sites on a KDP (potassium dihydrogen phosphate) surface and then improve the laser damage resistance of the components. However, the repaired KDP surface could cause light propagating turbulence and downstream light intensification with the potential risk to damage downstream optics. In order to analyze the downstream light field modulation caused by Gaussian mitigation pits on KDP crystals, a computational model of the downstream light diffraction based on the angular spectrum theory and the Gaussian repair contour is established. The results show that the phase offset caused by the repaired surface produces a large light field modulation near the rear KDP surface. The modulation generated in the whole downstream light field is greater than that caused by the amplitude change. Therefore, the phase characteristics of the outgoing light could be suggested as a vital research topic for future research on the downstream light field modulation caused by mitigation contours. Significantly, the experimental results on the downstream light intensity distribution have good agreement with the simulation ones, which proves the validity of the established downstream light diffraction model. The phase characterization of the outgoing light is proposed as an evaluation tool in the repair of KDP crystals. The developed analytical method and numerical discrete algorithm could be also applicable in qualifying the repair quality of other optical components applied in high-power laser systems. Copyright © 2020, The Authors. All rights reserved.

关键词： Diffraction

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Object-aware hybrid map for indoor robot visual semantic navigation

Object-aware hybrid map for indoor robot visual semantic nav...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Wang, Li Li, Ruifeng Sun, Jingwen Zhao, Lijun Shi, Hezi Seah, Hock Soon Tandianus, Budianto Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin150001 China School of Computer Science and Engineering Nanyang Technological University Nanyang Avenue639798 Singapore

ISBN: (纸本)9781728163215

In order to achieve an intuitive interaction and visual semantic navigation for the indoor robot, we propose a novel object-aware hybrid map. The existing map is usually a metric map, lacking semantics for interaction. We combine objects in the indoor environment with the metric map to constitute a hybrid map. The map consists of a 3D object semantic map and a 2D occupancy grid map, which transfers human commands to the grid map through object semantics, thereby enabling autonomous navigation for the robot. We utilize ORB-SLAM2 for continuous pose estimation and 3D mapping. 2D object detection in key-frames is conducted based on YOLO v3. The object point clouds in multiple perspectives are merged and a 3D bounding box of the object is estimated. These objects construct a 3D semantic map. Furthermore, we project a 3D point cloud map into a 2D plane in order to get an occupancy grid map. Finally, these two maps are combined forming an object-aware hybrid map. We conduct experiments in real environments in order to verify the feasibility and robustness of the hybrid map for robot semantic navigation. © 2019 IEEE.

关键词： Object detection

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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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An inertial navigation pre-integration algorithm based on multi-sensor fusion for indoor mobile robot positioning 2019

An inertial navigation pre-integration algorithm based on mu...

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2nd International Conference on Service robotics Technologies, ICSRT 2019

作者： Kong, Minxiu Niu, Caoyuan State Key Laboratory of Robotics and System No. 2 Xidazhi Street Nangang District Harbin Heilongjiang China Harbin Institute of Technology No. 2 Xidazhi Street Nangang District Harbin Heilongjiang China

ISBN: (纸本)9781450362467

Accurate position estimation is a key technology for mobile robots to reflect intelligence. It has very important research value and significance. In order to solve the problems of large error, low precision and error accumulation over time of the current algorithm, this paper proposes an inertial navigation pre-integration algorithm integrating multiple sensors, and estimates the initial visual scale s with the loose-coupling algorithm. Aiming at the low positioning accuracy of the loose-coupling algorithm, a tight coupling algorithm based on multi-sensor fusion is proposed, and the system model and observation model are delivered. Finally, the establishment of the Create2 experimental platform and the corresponding software design, and then the positioning and contrast experiments on different material surfaces, the comparison of positioning accuracy in indoor small scenes and large scenes, and the optimization of VISLAM system for tight coupling algorithms based on multi-sensor fusion The comparison experiment is carried out to verify the robustness and feasibility of the algorithm, and to test the positioning accuracy of the actual application scenario of the mobile robot. © 2019 Association for Computing Machinery.

关键词： Mobile robots

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Static Force Analysis of Foot of Electrically Driven Heavy-Duty Six-Legged Robot under Tripod Gait

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Chinese Journal of Mechanical Engineering 2018年第4期31卷 58-72页

作者： Zhen Liu Hong-Chao Zhuang Hai-Bo Gao Zong-Quan Deng Liang Ding State Key Laboratory of Robotics and System Harbin Institute of Technology College of Mechanical Engineering Tianjin University of Technology and Education

The electrically driven six-legged robot with high carrying capacity is an indispensable equipment for planetary exploration, but it hinders its practicability because of its low efficiency of carrying energy. Meanwhile, its load capacity also affects its application range. To reduce the power consumption, increase the load to mass ratio, and improve the stability of robot, the relationship between the walking modes and the forces of feet under the tripod gait are researched for an electrically driven heavy-duty six-legged robot. Based on the configuration characteristics of electrically driven heavy-duty six-legged, the typical walking modes of robot are analyzed. The mathematical models of the normal forces of feet are respectively established under the tripod gait of typical walking modes. According to the MATLAB software, the variable tendency charts are respectively gained for the normal forces of feet. The walking experiments under the typical tripod gaits are implemented for the prototype of electrically driven heavy-duty six-legged robot. The variable tendencies of maximum normal forces of feet are acquired. The comparison results show that the theoretical and experimental data are in the same trend. The walking modes which are most available to realize the average force of distribution of each foot are confirmed. The proposed method of analyzing the relationship between the walking modes and the forces of feet can quickly determine the optimal walking mode and gait parameters under the average distribution of foot force, which is propitious to develop the excellent heavy-duty multi-legged robots with the lower power consumption, larger load to mass ratio, and higher stability.

关键词： Electrically driven Heavy-duty six-legged robot Tripod gait Force of foot Walking mode

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Trajectory Optimization for a Six-DOF Cable-Suspended Parallel Robot with Dynamic Motions Beyond the Static Workspace

Trajectory Optimization for a Six-DOF Cable-Suspended Parall...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Sheng Xiang Haibo Gao Zhen Liu Clément Gosselin State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Département de génie mécanique Université Laval Québec City Canada

ISBN: (数字)9781728173955

ISBN: (纸本)9781728173962

This paper presents a trajectory optimization formulation for planning dynamic trajectories of a six-degree-of-freedom (six-DOF) cable-suspended parallel robot (CSPR) that extend beyond the static workspace. The optimization is guided by low-dimensional dynamic models to overcome the local minima and accelerate the exploration of the narrow feasible state space. The dynamic similarity between the six-DOF CSPR and the three-DOF point-mass CSPR is discussed with the analyses of their feasible force polyhedra. Finally, the transition trajectories of a three-DOF CSPR are used as the initial guess of the translational part of the six-DOF motion. With the proposed approach, highly dynamic motions for a six-DOF CSPR are efficiently generated with multiple oscillations. The feasibility is demonstrated by point-to-point and periodic trajectories in the physics simulation.

关键词： Dynamics Planning Robots Trajectory optimization Chebyshev approximation

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Diffusive nonreciprocity and thermal diode

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Physical Review B 2021年第1期103卷 014307-014307页

作者： Ying Li Jiaxin Li Minghong Qi Cheng-Wei Qiu Hongsheng Chen Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou 310027 China International Joint Innovation Center ZJU-UIUC Institute The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

Wave propagation and diffusion in linear materials preserve local reciprocity in terms of a symmetric Green's function. For wave propagations, the relation between the fields entering and leaving a system is more relevant than the detailed information about the fields inside it. In such cases, the global reciprocity of the scattering off a system through several ports is more important, which is defined as the symmetric transmission between the scattering channels. When a two-port system supports nonreciprocal (electromagnetic, acoustic) wave propagation, it is a (optical, phonon) diode directly following the definition. However, to date no concrete definition or discussion has been made on the global reciprocity of diffusive processes through a multiple-port system. It thus remains unclear what are the differences and relations between the three concepts, namely, local nonreciprocity, global nonreciprocity, and diode effect in diffusion. Here, we provide theoretical analysis on the frequency-domain Green's function and define the global reciprocity of heat diffusion through a two-port system, which has a different setup from that of a thermal diode. We further prove the equivalence between a heat transfer system with broken steady-state global reciprocity and a thermal diode, assuming no temperature-dependent heat generation. The validities of some typical mechanisms in breaking the diffusive reciprocity and making a thermal diode have been discussed. Our results set a general background for future studies on symmetric and asymmetric diffusive processes.

关键词： Diffusion Heat transfer Metamaterials Diodes Green's function methods

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Joint moment estimation for hip exoskeleton control: A generalized moment feature generation method

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Biomimetic Intelligence and robotics 2025年

作者： Yuanwen Zhang Jingfeng Xiong Haolan Xian Chuheng Chen Xinxing Chen Haipeng Liang Chenglong Fu Yuquan Leng State Key Laboratory of Robotics and Systems School of Biomedical Engineering Harbin Institute of Technology Shenzhen 518055 China Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Guangdong Provincial Key Laboratory of Human-Augmentation and Rehabilitation Robotics Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen 518055 China School of Engineering and Materials Science Queen Mary University of London London E1 4NS UK

Hip joint moments during walking are the key foundation for hip exoskeleton assistance control. Most recent studies have shown estimating hip joint moments instantaneously offers a lot of advantages compared to generating assistive torque profiles based on gait estimation, such as simple sensor requirements and adaptability to variable walking speeds. However, existing joint moment estimation methods still suffer from a lack of personalization, leading to estimation accuracy degradation for new users. To address the challenges, this paper proposes a hip joint moment estimation method based on generalized moment features (GMF). A GMF generator is constructed to learn GMF of the joint moment which is invariant to individual variations while remaining decodable into joint moments through a dedicated decoder. Utilizing this well-featured representation, a GRU-based neural network is used to predict GMF with joint kinematics data, which can easily be acquired by hip exoskeleton encoders. The proposed estimation method achieves a root mean square error of 0.1180 ± 0.0021 Nm/kg under 28 walking speed conditions on a treadmill dataset, improved by 6.5% compared to the model without body parameter fusion, and by 8.3% for the conventional fusion model with body parameter. Furthermore, the proposed method was employed on a hip exoskeleton with only encoder sensors and achieved an average 20.5% metabolic reduction ( p < 0 . 01 ) for users compared to assist-off condition in level-ground walking.

关键词： Lower-limb exoskeleton Hip joint moment estimation Deep learning

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