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Singularity loci of an orthogonal spherical two-degree-of-freedom parallel mechanism
Jialun YANG, Feng GAO,
《机械工程前沿（英文）》 2009年 第4卷 第4期 页码 379-385 doi: 10.1007/s11465-009-0075-0
关键词： 2-DOF orthogonal spherical parallel mechanism singularity loci self-motions
Influence of kinematic redundancy on the singularity-free workspace of parallel kinematic machines
Jens KOTLARSKI, Bodo HEIMANN, Tobias ORTMAIER
《机械工程前沿（英文）》 2012年 第7卷 第2期 页码 120-134 doi: 10.1007/s11465-012-0321-8
In this paper the effect of kinematic redundancy in order to reduce the singularity loci of the direct kinematics and to increase the operational, i.e., singularity-free, workspace is demonstrated. The proposed approach consists of additional prismatic actuators allowing one or more base joints to move linearly. As a result, a selective reconfiguration can be performed in order to avoid singular configurations. Exemplarily, kinematically redundant schemes of four structures, the 3RRR, the 3RPR, the 6UPS, and the 6RUS, are considered. The relationship between the redundancy and the operational workspace is studied and several analysis examples demonstrate the effectiveness of the proposed concept. Furthermore, the additional benefit of an increasing number of redundant actuators is discussed.
关键词： parallel robots kinematic redundancy singularity avoidance operational workspace
Guizhong XIE,Dehai ZHANG,Jianming ZHANG,Fannian MENG,Wenliao DU,Xiaoyu WEN
《机械工程前沿（英文）》 2016年 第11卷 第4期 页码 412-422 doi: 10.1007/s11465-016-0396-8
As a widely used numerical method, boundary element method (BEM) is efficient for computer aided engineering (CAE). However, boundary integrals with near singularity need to be calculated accurately and efficiently to implement BEM for CAE analysis on thin bodies successfully. In this paper, the distance in the denominator of the fundamental solution is first designed as an equivalent form using approximate expansion and the original sinh method can be revised into a new form considering the minimum distance and the approximate expansion. Second, the acquisition of the projection point by Newton-Raphson method is introduced. We acquire the nearest point between the source point and element edge by solving a cubic equation if the location of the projection point is outside the element, where boundary integrals with near singularity appear. Finally, the subtriangles of the local coordinate space are mapped into the integration space and the sinh method is applied in the integration space. The revised sinh method can be directly performed in the integration element. A verification test of our method is proposed. Results demonstrate that our method is effective for regularizing the boundary integrals with near singularity.
关键词： computer aided engineering (CAE) boundary element method (BEM) near singularity sinh method coordinate transformation integration space
马景兰,王伟,万京生,张永丽
《中国工程科学》 2009年 第11卷 第8期 页码 93-96
低频振荡是影响电力系统稳定运行的一个重要方面。阐述了低频振荡产生的机理和分析方法，利用Hopf分歧理论，针对一个四阶模型的单机无穷大系统，分析了在临界点附近时可能出现的非线性奇异现象。研究表明：由于分歧的存在，导致系统稳定性在临界点附近出现奇异，从而影响了电力系统的稳定域。
Alin STOICA, Doina PISLA, Szilaghyi ANDRAS, Bogdan GHERMAN, Bela-Zoltan GYURKA, Nicolae PLITEA
《机械工程前沿（英文）》 2013年 第8卷 第1期 页码 70-79 doi: 10.1007/s11465-013-0365-4
In the last ten years, due to development in robotic assisted surgery, the minimally invasive surgery has greatly changed. Until now, the vast majority of robots used in surgery, have serial structures. Due to the orientation parallel module, the structure is able to reduce the pressure exerted on the entrance point in the patient’s abdominal wall. The parallel robot can also handle both a laparoscope as well an active instrument for different surgical procedures. The advantage of this parallel structure is that the geometric model has been obtained through an analytical approach. The kinematic modelling of a new parallel architecture, the inverse and direct geometric model and the inverse and direct kinematic models for velocities and accelerations are being determined. The paper will demonstrate that with this parallel structure, one can obtain the necessary workspace required for a minimally invasive operation. The robot workspace was generated using the inverse geometric model. An in-depth study of different types of singularity is performed, allowing the development of safe control algorithms of the experimental model. Some kinematic simulation results and the experimental model of the robot are presented in the paper.
关键词： parallel robot minimally invasive surgery kinematics simulation
Po-Chih LEE, Jyh-Jone LEE
《机械工程前沿（英文）》 2012年 第7卷 第2期 页码 163-187 doi: 10.1007/s11465-012-0324-5
This paper presents the analysis of three parallel manipulators with Schoenflies-motion. Each parallel manipulator possesses two limbs in structure and the end-effector has three DOFs (degree of freedom) in the translational motion and one DOF in rotational motion about a given direction axis with respect to the world coordinate system. The three isoconstrained parallel manipulators have the structures denoted as CuuUwHw-//-CvvUwHw, CuRuuUhw-//-CvRvvUhwand CuPuUhw-//- CvPvUhw. The kinematic equations are first introduced for each manipulator. Then, Jacobian matrix, singularity, workspace, and performance index for each mechanism are subsequently derived and analysed for the first time. The results can be helpful for the engineers to evaluate such kind of parallel robots for possible application in industry where pick-and-place motion is required.
关键词： parallel manipulator schoenflies motion kinematics singularity workspace performance index
null
《机械工程前沿（英文）》 2014年 第9卷 第3期 页码 281-294 doi: 10.1007/s11465-014-0307-9
In this study, the stress concentration factors (SCF) in cross-and-angle-ply laminated composite plates as well as in isotropic plates with single circular holes subjected to uniaxial loading is studied. A quadrilateral finite element of four-node with 32 degrees of freedom at each node, previously developed for the bending and mechanical buckling of laminated composite plates, is used to evaluate the stress distribution in laminated composite plates with central circular holes. Based up on the classical plate theory, the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element. The numerical results obtained by the present element compare favorably with those obtained by the analytic approaches published in literature. It is observed that the obtained results are very close to the reference results, which demonstrates the accuracy of the present element. Additionally, to determine the first ply failure (FPF) of laminated plate, several failure criterions are employed. Finally, to show the effect of ratio on the failure of plates, a number of figures are given for different fiber orientation angles.
关键词： laminated composite plates stress concentration geometric singularity anisotropic effect
Ruiming LI,Yan-An YAO
《机械工程前沿（英文）》 2016年 第11卷 第2期 页码 159-169 doi: 10.1007/s11465-016-0398-6
In this study, a novel duoprism mechanism that demonstrates a fascinating eversion motion is developed. The mechanism comprises three scalable platforms and nine retractable limbs and is constructed by inserting prismatic and revolute joints into the edges and vertices of the duoprism, respectively. According to mobility and kinematic analyses, the mechanism has five degrees of freedom. Six inputs, including a redundant one, are required to overcome singularity and achieve an eversion motion. In the eversion motion, three platforms expand/contract synchronously, and the mechanism continuously turns inside out. The detailed gaits of eversion motion along an ellipse and a circle after a cycle are illustrated with two examples. A kinematic simulation is conducted, and a manual prototype is fabricated to verify the feasibility of the eversible duoprism mechanism.
Self-motions of 3-RPS manipulators
Josef SCHADLBAUER, Manfred L. HUSTY, Stéphane CARO, Philippe WENGERY
《机械工程前沿（英文）》 2013年 第8卷 第1期 页码 62-69 doi: 10.1007/s11465-013-0366-3
Recently a complete kinematic description of the 3-RPS parallel manipulator was obtained using algebraic constraint equations. It turned out that the workspace splits into two components describing two kinematically different operation modes. In this paper the algebraic description is used to give a complete analysis of all possible self-motions of this manipulator in both operation modes. Furthermore it is shown that a transition from one operation mode into the other in a self-motion is possible.
Multifractal characteristics of cylindrical sludge drying
Weiyun WANG, Aimin LI,
《环境科学与工程前沿（英文）》 2009年 第3卷 第4期 页码 464-469 doi: 10.1007/s11783-009-0040-5
关键词： multifractal characteristic multifractal singularity spectrum sewage sludge drying
《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0695-1
关键词： translational parallel mechanism single loop multiple driving system workspace analysis singularity
《机械工程前沿（英文）》 2021年 第16卷 第4期 页码 726-746 doi: 10.1007/s11465-021-0651-5
关键词： parallel mechanism upper-limb rehabilitation singularity and workspace analyses performance evaluation optimum design
Fugui XIE,Xin-Jun LIU
《机械工程前沿（英文）》 2016年 第11卷 第2期 页码 135-143 doi: 10.1007/s11465-016-0389-7
This study introduces a high-speed parallel robot with Schönflies 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
贺昌海,肖煥雄,胡志根,周宜红
《中国工程科学》 2001年 第3卷 第6期 页码 69-74
根据截流戗堤边坡的两种不同坍塌现象的特点，进行定性分析并总结其主要影响因素，包括抛投材料的抗冲能力、戗堤基础的抗冲能力、龙口水深、抛投材料的力学性质和抛投材料的浸水湿化。引用戗堤堆石的一个微结构模型，运用静态分叉和奇异性理论，进一步研究了戗堤堆石的分叉特性。结果表明，堆石内部的 应力变化和拋投材料的浸水湿化是深水截流中戗堤边坡高频率、大规模坍塌的根本原因。据此，提出了实际施 工时应采取的工程措施，并说明了模型戗堤边坡突然坍塌的可能性以及坍塌范围比原型要大的原因。
标题 作者 时间 类型 操作
Singularity loci of an orthogonal spherical two-degree-of-freedom parallel mechanism
Jialun YANG, Feng GAO,
期刊论文
Influence of kinematic redundancy on the singularity-free workspace of parallel kinematic machines
Jens KOTLARSKI, Bodo HEIMANN, Tobias ORTMAIER
期刊论文
Implementation of sinh method in integration space for boundary integrals with near singularity in potential
Guizhong XIE,Dehai ZHANG,Jianming ZHANG,Fannian MENG,Wenliao DU,Xiaoyu WEN
期刊论文
Kinematic, workspace and singularity analysis of a new parallel robot used in minimally invasive surgery
Alin STOICA, Doina PISLA, Szilaghyi ANDRAS, Bogdan GHERMAN, Bela-Zoltan GYURKA, Nicolae PLITEA
期刊论文
Singularity and workspace analysis of three isoconstrained parallel manipulators with schoenflies motion
Po-Chih LEE, Jyh-Jone LEE
期刊论文
Finite element analysis of stress concentrations and failure criteria in composite plates with circular holes
null
期刊论文
Self-motions of 3-RPS manipulators
Josef SCHADLBAUER, Manfred L. HUSTY, Stéphane CARO, Philippe WENGERY
期刊论文
Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures
期刊论文
Optimum design and preliminary experiments of a novel parallel end traction apparatus for upper-limb rehabilitation
期刊论文
kinematic characteristics of a high-speed parallel robot with Schönflies motion: Mobility, kinematics, and singularity
Fugui XIE,Xin-Jun LIU
期刊论文
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