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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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PCF-Grasp: Converting Point Completion to Geometry Feature to Enhance 6-DoF Grasp

arXiv

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arXiv 2025年

作者： Cheng, Yaofeng Zha, Fusheng Guo, Wei Wang, Pengfei Zeng, Chao Sun, Lining Yang, Chenguang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Lanzhou University of Technology China Department of Computer Science University of Liverpool LiverpoolL69 3BX United Kingdom

The 6-Degree of Freedom (DoF) grasp method based on point clouds has shown significant potential in enabling robots to grasp target objects. However, most existing methods are based on the point clouds (2.5D points) generated from single-view depth images. These point clouds only have one surface side of the object providing incomplete geometry information, which mislead the grasping algorithm to judge the shape of the target object, resulting in low grasping accuracy. Humans can accurately grasp objects from a single view by leveraging their geometry experience to estimate object shapes. Inspired by humans, we propose a novel 6-DoF grasping framework that converts the point completion results as object shape features to train the 6-DoF grasp network. Here, point completion can generate approximate complete points from the 2.5D points similar to the human geometry experience, and converting it as shape features is the way to utilize it to improve grasp efficiency. Furthermore, due to the gap between the network generation and actual execution, we integrate a score filter into our framework to select more executable grasp proposals for the real robot. This enables our method to maintain a high grasp quality in any camera viewpoint. Extensive experiments demonstrate that utilizing complete point features enables the generation of significantly more accurate grasp proposals and the inclusion of a score filter greatly enhances the credibility of real-world robot grasping. Our method achieves a 17.8% success rate higher than the state-of-the-art method in real-world experiments. Code and videos are available at https://***/ChengYaofeng/PCF-Grasp. Copyright © 2025, The Authors. All rights reserved.

关键词： Geometry

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An Optimal Control Formulation of Tool Affordance Applied to Impact Tasks

arXiv

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arXiv 2024年

作者： Ti, Boyang Gao, Yongsheng Zhao, Jie Calinon, Sylvain The State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin150001 China Idiap Research Institute MartignyCH-1920 Switzerland Lausanne1015 Switzerland

Humans use tools to complete impact-aware tasks such as hammering a nail or playing tennis. The postures adopted to use these tools can significantly influence the performance of these tasks, where the force or velocity of the hand holding a tool plays a crucial role. The underlying motion planning challenge consists of grabbing the tool in preparation for the use of this tool with an optimal body posture. Directional manipulability describes the dexterity of force and velocity in a joint configuration along a specific direction. In order to take directional manipulability and tool affordances into account, we apply an optimal control method combining iterative linear quadratic regulator (iLQR) with the alternating direction method of multipliers (ADMM). Our approach considers the notion of tool affordances to solve motion planning problems, by introducing a cost based on directional velocity manipulability. The proposed approach is applied to impact tasks in simulation and on a real 7-axis robot, specifically in a nail-hammering task with the assistance of a pilot hole. Our comparison study demonstrates the importance of maximizing directional manipulability in impact-aware tasks. Copyright © 2024, The Authors. All rights reserved.

关键词： Motion planning

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A Combined Inverse Kinematics Algorithm Using FABRIK with Optimization

arXiv

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arXiv 2022年

作者： Xu, Zichun Li, Yuntao Yang, Xiaohang Zhao, Zhiyuan Zhao, Jingdong Liu, Hong The State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Province Harbin150001 China

Forward and backward reaching inverse kinematics (FABRIK) is a heuristic inverse kinematics solver that is gradually applied to manipulators with the advantages of fast convergence and generating more realistic configurations. However, under the high error constraint, FABRIK exhibits unstable convergence behavior, which is unsatisfactory for the real-time motion planning of manipulators. In this paper, a novel inverse kinematics algorithm that combines FABRIK and the sequential quadratic programming (SQP) algorithm is presented, in which the joint angles deduced by FABRIK will be taken as the initial seed of the SQP algorithm to avoid getting stuck in local minima. The combined algorithm is evaluated with experiments, in which our algorithm can achieve higher success rates and faster solution times than FABRIK under the high error constraint. Furthermore, the combined algorithm can generate continuous trajectories for the UR5 and KUKA LBR IIWA 14 R820 manipulators in path tracking with no pose error and permitted position error of the end-effector. Copyright © 2022, The Authors. All rights reserved.

关键词： Inverse kinematics

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Energy Harvesting in the Wake of An Inverted C-Shaped Bluff Body

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China Ocean Engineering 2024年第1期38卷 68-80页

作者： WANG Jun-lei LI Shen-fang Md.Mahbub ALAM ZHU Hong-jun HU Guo-biao School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450000China Center for Turbulence Control Harbin Institute of Technology(Shenzhen)Shenzhen 518055China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China Internet of Things Thrust The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511400China

This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff *** inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV *** hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental *** reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present *** is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH *** the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested *** the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or *** average drag coefficient becomes negative when L is 2D,3D,or *** carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH *** example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional ***,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.

关键词： wake-induced vibration vortex-induced vibration galloping energy harvesting bluff body

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A novel design of force-feedback master manipulator for remote ultrasound scanning

A novel design of force-feedback master manipulator for remo...

引用

IEEE International Conference on robotics and Biomimetics

作者： ChangLe Li ChenTao Zhang Chuan You Yu LeiFeng Zhang GangFeng Liu Jie Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology HeiLongJiang China

ISBN: (纸本)9781665481106

This paper presents a novel six-degree-of-freedom force feedback master manipulator for remote ultrasound scanning. Firstly, a new configuration based on a planar five-link mechanism is proposed, taking into account the practical needs of medical ultrasound scanning. This configuration has two operating modes and can provide three degrees of force feedback. Secondly, a hybrid force/position master-slave control system based on the kinetic model force feedback method is built, which can realize incremental master-slave control, variable proportional control, force feedback, and other functions. Finally, the positional accuracy, gravity balance effect, and force feedback performance of this master manipulator are verified through experiments. Experiments show that the average position error of this novel force feedback master manipulator is 1.18 mm, the average attitude error expressed in terms of Euler angles is 0.83°, and the maximum feedback force that can be provided is 12.1 N, which satisfies the requirements of ultrasonic scanning.

关键词： Ultrasonic imaging Tracking Proportional control Machine vision Force feedback Manipulators Main-secondary

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Permanent Magnet Shape Optimization Method for PMSM Air Gap Flux Density Harmonics Reduction

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CES Transactions on Electrical Machines and systems 2021年第4期5卷 284-290页

作者： Chengsi Liu Yongxiang Xu Jibin Zou Guodong Yu Liang Zhuo School of Electrical Engineering and Automation of HIT Department of Electrical Engineering Harbin Institute of Technology the State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Institute of Technology and National Engineering Research Center for Small and Special Precision Motors Guizhou Aerospace Linquan Motor Co.Ltd

This paper proposed a permanent magnet optimization method to suppress the air gap flux density harmonic of permanent magnet synchronous motor(PMSM).The method corrected the effective air gap length of the motor,calculated the magnetization length of the permanent in the case of parallel magnetization,and took the influence of the permanent magnet relative permeability into *** on these works,for a given sinusoidal air gap flux density waveform,the corresponding structural parameters can be calculated,so as to achieve the optimization of the permanent *** using this method to optimize the shape of the magnet,the fundamental wave of the air gap flux density can be retained to the greatest extent,so as to eliminate harmonics and maintain the output capacity at the same *** feasibility and accuracy of the method have been verified by finite element analysis(FEA)and prototype machine *** method is simple and time-saving,and has a satisfactory accuracy,which provides a reference method for permanent magnet optimization of PMSM.

关键词： Permanent magnet synchronous motor(PMSM) analytical method finite element analysis(FEA) magnet shape optimization.

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FlexDelta: A flexure-based fully decoupled parallel xyz positioning stage with long stroke

arXiv

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arXiv 2023年

作者： Zhang, Qianjun Dong, Wei Xu, Qingsong Goteea, Bimal J. Gao, Yongzhuo State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150000 China Department of Electromechanical Engineering Faculty of Science and Technology University of Macau Macau999078 China

Decoupled parallel xyz positioning stages with large stroke have been desired in high-speed and precise positioning fields. However, currently such stages are either short in stroke or unqualified in parasitic motion and coupling rate. This paper proposes a novel flexure-based decoupled parallel xyz positioning stage (FlexDelta) and conducts its conceptual design, modeling, and experimental study. Firstly, the working principle of FlexDelta is introduced, followed by its mechanism design with flexure. Secondly, the stiffness model of flexure is established via matrix-based Castigliano’s second theorem, and the influence of its lateral stiffness on the stiffness model of FlexDelta is comprehensively investigated and then optimally designed. Finally, experimental study was carried out based on the prototype fabricated. The results reveal that the positioning stage features centimeter-stroke in three axes, with coupling rate less than 0.53%, parasitic motion less than 1.72 mrad over full range. And its natural frequencies are 20.8 Hz, 20.8 Hz, and 22.4 Hz for x, y, and z axis respectively. Multi-axis path tracking tests were also carried out, which validates its dynamic performance with micrometer error. Copyright © 2023, The Authors. All rights reserved.

关键词： Stiffness

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Understanding of isoelectronic alloying induced energy gap variation for a large enhancement of thermoelectric power factor

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Physical Review B 2024年第15期109卷 155203-155203页

作者： Xingyan Dong Jianbo Zhu Yu-ke Zhu Ming Liu Liangjun Xie Nuo Qu Yifan Jin Xiaohan Jiang Fengkai Guo Zihang Liu Wei Cai Jiehe Sui State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001 China Capital Aerospace Machinery Corporation Limited Beijing 100076 China

Band-structure engineering is an important strategy that can improve the properties of functional materials or even bring new features to existing systems. Band gap (or energy gap, Eg) plays a crucial role in deciding the electronic or optical properties of one material. Isoelectronic and isostructural alloys usually exhibit similar electronic band structures, but the related effect of Eg variation was found to be distinct and sometimes controversial. Herein, we provided a deep understanding of the origin of band tuning in isoelectronic alloys based on experimental characterizations and theoretical calculations. The prerequisites of an isoelectronic alloy system with an Eg that is sensitive to composition are thoroughly disclosed by studying (Sb,Bi)2Te3 and Pb(Se,Te). In the promising Mg3(Sb,Bi)2 thermoelectric materials, it is found that Bi isoelectronic substitution can significantly decrease the Eg, due to the combination of the higher energy of Bi 6p orbit than that of Sb 5p orbit and the varied bond strength induced by lattice expanding. A high room-temperature power factor (PF) value of 38.5µWcm−1K−2 is obtained in nearly zero-gap Mg3.2Sb0.3Bi1.7 samples, which rationally guides the design of thermoelectric materials in the aspect of electronic transport.

关键词： Electrical conductivity Doped semiconductors Narrow band gap systems Semiconductors Electronic structure

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SparkRA: A Retrieval-Augmented Knowledge Service system Based on Spark Large Language Model

SparkRA: A Retrieval-Augmented Knowledge Service System Base...

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2024 Conference on Empirical Methods in Natural Language Processing: system Demonstrations, EMNLP 2024

作者： Wu, Dayong Li, Jiaqi Wang, Baoxin Zhao, Honghong Xue, Siyuan Yang, Yanjie Chang, Zhijun Zhang, Rui Qian, Li Wang, Bo Wang, Shijin Zhang, Zhixiong Hu, Guoping State Key Laboratory of Cognitive Intelligence iFLYTEK Research China University of Science and Technology of China Hefei China Research Center for Social Computing and Information Retrieval Harbin Institute of Technology Harbin China National Science Library Chinese Academy of Sciences China Langfang China

ISBN: (纸本)9798891761674

Large language models (LLMs) have shown remarkable achievements across various language tasks. To enhance the performance of LLMs in scientific literature services, we developed the scientific literature LLM (SciLit-LLM) through pre-training and supervised fine-tuning on scientific literature, building upon the iFLYTEK Spark LLM. Furthermore, we present a knowledge service system Spark Research Assistant (SparkRA) based on our SciLit-LLM. SparkRA is accessible online and provides three primary functions: literature investigation, paper reading, and academic writing. As of July 30, 2024, SparkRA has garnered over 50, 000 registered users, with a total usage count exceeding 1.3 million. © 2024 Association for Computational Linguistics.

关键词： Computational linguistics

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