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Velocity Constraints Based Approach for Online Trajectory Planning of High‑Speed Parallel Robots

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Chinese Journal of Mechanical Engineering 2022年第6期35卷 98-109页

作者： Di Yang fugui xie Xinjun Liu State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Beijing Key Lab of Precision/Ultra‑Precision Manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China

High-speed parallel robots have been extensively utilized in the light ***,the influence of the nonlinear dynamic characteristics of high-speed parallel robots on system’s dynamic response and stable operation cannot be ignored during the high-speed reciprocating ***,trajectory planning is essential for efficiency and stability from pick-and-place(PAP)*** paper presents a method for planning the equal-height pick-and-place trajectory considering velocity constraints to improve the PAP efficiency and stability of high-speed parallel *** velocity constraints in the start-and-end points can reduce vibration from picking and placing,making the trajectory more suitable to complex beltline *** on velocity constraints,trajectory optimization includes trajectory smoothness and joint torque to optimize cycle time is carried *** paper proposes an online trajectory optimization *** using back propagation(BP)neural networks,the solution is simplified and can be solved in *** and experiments were carried out on the SR4 parallel *** results show that the proposed method improves the efficiency,smoothness,and stability of the *** paper proposes an online trajectory planning method which is velocity constraints based and can improve the efficiency and stability of high-speed parallel *** work of this research is conducive to finely applying high-speed parallel robots.

关键词： Trajectory planning High-speed parallel robot Velocity constraints BP neural network

An energy efficiency evaluation method for parallel robots based on the kinetic energy change rate

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Science China(Technological Sciences) 2019年第6期62卷 1035-1044页

作者： LIU XinJun BI WeiYao xie fugui The State Key Laboratory of Tribology & Tsinghua University (DME)-Siemens Joint Research Center for Advanced Robotics Department of Mechanical Engineering (DME) Tsinghua University Beijing 100084 China Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University Beijing 100084 China

Benefit from the high payload-to-weight ratio, parallel robots are expected to have a high potential for energy savings. However,it is a challenging issue to evaluate the energy efficiency of parallel robots with a quantitative method. Quantitative energy efficiency evaluation methods include energy efficiency evaluation models and indices which mathematically describe the relationship between energy consumers in models and design variables of robots, such as geometry, mass and inertia *** the structural features of parallel robots, the chains and the end effectors are identified as two separated energy consumers. Besides, the chains in parallel robots are identified as a transmission system which transfers energy from drives to the end effectors. On this basis, an energy efficiency evaluation model considering the change rate of kinetic energy stored in chains is built. The kinetic energy change rate of chains is influenced by design variables of robots as well as motion of the end *** order to give a quantitative description of energy efficiency performance of parallel robots, indices considering arbitrary velocity vector of the end effector are proposed. The evaluation method is suitable for all kinds of parallel robots with various motion conditions. Furthermore, the method can be used to optimize machining parameters and guide the design of energyefficient machines.

关键词： energy efficiency evaluation parallel robots kinetic energy power transmission

Optimal Design of a Main Driving Mechanism for Servo Punch Press Based on Performance Atlases

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Chinese Journal of Mechanical Engineering 2013年第5期26卷 909-917页

作者： ZHOU Yanhua xie fugui LIU Xinjun Department of Precision Instruments and Mechanology Tsinghua University Institute of Aircraft Engineering Naval Aeronautical and Astronautical University Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy *** effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are *** the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are *** non-dimensional normalization method is used to get all feasible solutions in dimensional ***,the performance atlases,which can present all possible design solutions,are *** a result,the feasible solution of the mechanism with good motion/force transmission performance is *** the solution can be flexibly adjusted by designer according to the practical design *** proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

关键词： servo punch press main driving mechanism dimensional optimization transmission index performance atlas

Type Synthesis of 4-DOF Parallel Kinematic Mechanisms Based on Grassmann Line Geometry and Atlas Method

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1073-1081页

作者： xie fugui LI Tiemin LIU Xinjun Department of Mechanical Engineering Tsinghua University Department of Precision Instruments Tsinghua University Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University

Many methods are proposed to deal with the type synthesis of parallel kinematic mechanisms（PKMs）, but most of them are less intuitive to some extent. Thus, to propose a concise and intuitive type synthesis method for engineering application is a very challenging issue, which should be further studied in the field. Grassmann line geometry, which can investigate the dimensions of spatial line-clusters in a concise way, is taken as the mathematic foundation. Atlas method is introduced to visually describe the degrees of freedom（DOFs） and constraints of a mechanism, and the dual rule is brought in to realize the mutual conversion of the freedom-space and constraint-space. Consequently, a systematic method based on Grassmann line geometry and Atlas method is generated and the entire type synthesis process is presented. Three type 4-DOF PKMs, i.e., 1T3R, 2T2R and 3T1R（T： translational DOF; R： rotational DOF）, are classified according to the different combinations of the translational DOFs and rotational DOFs. The type synthesis of 4-DOF PKMs is carried out and the possible configurations are thoroughly investigated. Some new PKMs with useful functions are generated during this procedure. The type synthesis method based on Grassmann line geometry and Atlas method is intuitive and concise, and can reduce the complexity of the PKMs＇ type synthesis. Moreover, this method can provide theoretical guidance for other PKMs＇ type synthesis and engineering application. A novel type synthesis method is proposed, which solves the existing methods＇ problems in terms of complicated, not intuitive and unsuitable for practical application.

关键词： type synthesis parallel kinematic mechanism Grassmann line geometry atlas method

Analysis of the kinematic characteristics of a high-speed parallel robot with Sch6nflies motion： Mobility, kinematics, and singularity

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Frontiers of Mechanical Engineering 2016年第2期11卷 135-143页

作者： fugui xie Xin-Jun LIU The State Key Laboratory of Tribology & Institute of Manufacturing Engineering Department of Mechanical Engineering Tsinghua Uni- versity Beijing 100084 China Beijing Key Laboratory of Precision/ Ultra-precision Manufacturing Equipment and Control Tsinghua University Beijing 100084 China

This study introduces a high-speed parallel robot with Schonflies motion. This robot exhibits a promising prospect in realizing high-speed pick-and- place manipulation for packaging production lines. The robot has four identical limbs and a single platform. Its compact structure and single-platform concept provides this robot with good dynamic response potential. A line graph method based on Grassmann line geometry is used to investigate the mobility characteristics of the proposed robot. A generalized Blanding rule is also introduced into this procedure to realize mutual conversion between the line graphs for motions and constraints. Subsequently, the inverse kinematics is derived, and the singularity issue of the robot is investigated using both qualitative and quantitative approaches. Input and output transmission singularity indices are defined based on the reciprocal product in screw theory and the virtual coefficient by considering motion/force transmission performance. Thereafter, the singular loci of the proposed robot with specific geometric parameters are derived. The mobility analysis, inverse kinematics modeling, and singularity analysis conducted in this study are helpful in developing the robot.

关键词： parallel robot mobility inverse kinematics,singularity transmission performance

Robotic mobile and mirror milling of large-scale complex structures

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National Science Review 2023年第5期10卷 10-13页

作者： Zenghui xie fugui xie Limin Zhu Xin-Jun Liu State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical Engineering(DME) Tsinghua University Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong University

Large-scale complex structures,such as spacecraft cabins,aircraft composite skins and launch vehicle fuel tanks,are the core components of the equipment in aerospace,energy,shipbuilding and other *** milling quality and efficiency are factors directly affecting the performance and productivity of spacecraft,aircraft and other key *** kind of structure generally features large dimension,high accuracy,

关键词： COMPENSATION PARTS

基于足底压力和卷积长短期记忆神经网络的前交叉韧带断裂智能辅助诊断

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北京大学学报（自然科学版） 2024年第1期60卷 109-117页

作者：李玳王天牧张思秦跃谢福贵刘辛军聂振国黄红拾北京大学第三医院运动医学科北京大学运动医学研究所运动医学关节伤病北京市重点实验室运动创伤治疗技术与器械教育部工程研究中心北京100191 摩擦学国家重点实验室清华大学机械工程系北京100084 精密/超精密制造设备与控制北京市重点实验室清华大学机械工程系北京100084

提出一种基于卷积长短期记忆神经网络的深度学习模型PressureConvLSTM,用来提取行走过程中足底压力的空间特征和时序特征,并进行步态分类。通过对前交叉韧带断裂患者的足底压力数据分析,实现智能辅助诊断。结合临床数据的实验结果表明,P... 详细信息

提出一种基于卷积长短期记忆神经网络的深度学习模型PressureConvLSTM,用来提取行走过程中足底压力的空间特征和时序特征,并进行步态分类。通过对前交叉韧带断裂患者的足底压力数据分析,实现智能辅助诊断。结合临床数据的实验结果表明,PressureConvLSTM模型对前交叉韧带断裂的辅助诊断,能够达到95%的预测准确度;与卷积神经网络等其他模型相比,准确度得到大幅度提升。

关键词：智能诊断前交叉韧带断裂足底压力深度学习卷积长短期记忆神经网络

Evolution and Development Trend Prospect of Metal Milling Equipment

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 1-15页

作者： Jie Wen fugui xie Xinjun Liu Yi Yue Department of Mechanical Engineering(DME) Tsinghua UniversityBeijing 100084China Beijing Key Lab of Precision/Ultra‑Precision Manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China Beijing Spacecrafts Beijing 100094China

The world is currently undergoing profound changes which have never happened within the past *** competition in the technology and industry fields is becoming increasingly *** strategic competition of the major powers further focuses on the manufacturing *** countries such as the United States,Germany,and Japan have successively put forward strategic plans such as“re-industrialization”and“return of manufacturing industry”,aiming to seize the commanding heights of a new round of global high-end technology competition and expand international market *** at the historic intersection of a new round of scientific and technological revolution and China's accelerated high-quality development,the“14th Five-Year Plan”clearly pointed out that intelligent manufacturing is the main development trend to promote China's manufacturing to the medium-high end of the global value *** reflects the importance of advanced manufacturing for national strategic *** better grasp the development direction of advanced manufacturing equipment,the development process and current application status of manufacturing equipment are summarized,and thereafter the characteristics of manufacturing equipment in different development stages of the manufacturing industry are ***,the development trend of advanced milling equipment is prospected.

关键词： Intelligent manufacturing High-quality development Milling equipment Evolution and development trend

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穿越溶洞桥梁桩基嵌岩深度计算方法研究

桥梁建设 2024年第3期54卷 109-116页

作者：陈慧芸冯忠居谢富贵赵瑞欣蔡杰西华大学建筑与土木工程学院四川成都610039 长安大学公路学院陕西西安710064 成都天府绿道建设投资集团有限公司四川成都610041 福建省交通建设质量安全中心福建福州350001

为准确计算岩溶区桥梁桩基嵌岩深度,依托莆炎高速公路岩溶区桥梁桩基工程,分别考虑桩基竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量,提出3种穿越溶洞桥梁桩基嵌岩深度计算方法,并验证3种方法的可靠性。选取34根代表性桩基... 详细信息

为准确计算岩溶区桥梁桩基嵌岩深度,依托莆炎高速公路岩溶区桥梁桩基工程,分别考虑桩基竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量,提出3种穿越溶洞桥梁桩基嵌岩深度计算方法,并验证3种方法的可靠性。选取34根代表性桩基对比嵌岩深度设计值与所提方法计算值,并选取1根试桩对比规范值与所提方法计算值。结果表明:34根代表性桩基中,1根桩基的嵌岩深度设计值小于考虑全寿命周期内溶洞溶蚀量的嵌岩深度计算值,占比2.9%;10根桩基的嵌岩深度设计值同时满足竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量要求,且安全储备合理,占比29.5%;23根桩基存在安全储备较高问题,占比67.6%,其中14.7%的桩基嵌岩深度设计安全储备高达5倍。各规范关于桩基嵌岩深度的取值差异较大,为确保桥梁桩基承载安全,同时降低施工难度和成本,建议设计穿越溶洞桥梁桩基的合理嵌岩深度时,充分考虑桥梁全寿命周期内溶洞溶蚀量。

关键词：桩基岩溶区嵌岩深度竖向极限承载力桩身稳定性溶洞溶蚀量计算方法