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Stiffness of a 3-degree of freedom translational parallel kinematic machine

null

《机械工程前沿(英文)》 2014年 第9卷 第3期   页码 233-241 doi: 10.1007/s11465-014-0312-z

摘要:

In this paper, a typical 3-degree of freedom (3-DOF) translational parallel kinematic machine (PKM) is studied and analyzed whose tool platform has only translations along X-Y- and Z-axes. It consists of three limbs, each of which have arm and forearm with prismatic-revolute-revolute-revolute (PRRR) joints. Inverse kinematics analysis is carried out to find the slider coordinates and joint angles for a given position of tool platform. Stiffness modeling is done based on the compliance matrices of arm and forearm of each limb. Using the stiffness modeling the variations of minimum and maximum translational stiffness in the workspace are analyzed. For various architectural parameters of the 3-DOF PKM the tendency of variations on the minimum and maximum stiffness over the entire workspace is studied; and also the deflections of the tool platform along XY, and Z directions with respect to various forces are presented.

关键词: 3-DOF translational PKM     inverse kinematics     stiffness modeling     translational stiffness    

Manufacturing error analysis of compliant 3-DOF microrobot

CHAO Dai-hong, LIU Rong, WU Yue-min, SHI Long, ZONG Guang-hua

《机械工程前沿(英文)》 2006年 第1卷 第3期   页码 299-304 doi: 10.1007/s11465-006-0030-2

摘要: In the fields of micro/nanopositioning application, error analysis is an effective way to enhance the precision of micromanipulators. Manufacturing imperfections, which are inevitable, are the most important factors influencing the accuracy. Therefore, various manufacturing imperfections were studied by taking a planar 3 degrees of freedom (3-DOF) flexure hinge based microrobot as a case. By formulating static stiffness of the robot, mapping between manufacturing imperfections and end-effector positioning accuracy was obtained. Using the theoretical calculation and finite element method (FEM), effects of various machining imperfection types on end-effector positioning accuracy were evaluated. The results showed that errors of the radium of the hinges and angular differences of the centerline of the hinges were dominant factors resulting in output errors. Conclusions drawn from the experiments can be used to instruct the design of compliant parallel mechanisms by distributing various manufacturing differences of configurable parameters to guarantee precision in the positioning of the end-effector within the required range; they may also be helpful while calibrating this kind of manipulator.

关键词: centerline     stiffness     effective     manipulator     precision    

Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 120-129 doi: 10.1007/s11465-014-0300-3

摘要:

In this paper, error modeling and analysis of a typical 3-degree of freedom translational Parallel Kinematic Machine is presented. This mechanism provides translational motion along the Cartesian X-, Y- and Z- axes. It consists of three limbs each having an arm and forearm with prismatic-revolute-revolute-revolute joints. The moving or tool platform maintains same orientation in the entire workspace due to its joint arrangement. From inverse kinematics, the joint angles for a given position of tool platform necessary for the error modeling and analysis are obtained. Error modeling is done based on the differentiation of the inverse kinematic equations. Variation of pose errors along XY and Z directions for a set of dimensions of the parallel kinematic machine is presented. A non-dimensional performance index, namely, global error transformation index is used to study the influence of dimensions and its corresponding global maximum pose error is reported. An attempt is made to find the optimal dimensions of the Parallel Kinematic Machine using Genetic Algorithms in MATLAB. The methodology presented and the results obtained are useful for predicting the performance capability of the Parallel Kinematic Machine under study.

关键词: translational Parallel Kinematic Machine     error modeling     global error transformation index    

LARM PKM solutions for torso design in humanoid robots

Marco CECCARELLI

《机械工程前沿(英文)》 2014年 第9卷 第4期   页码 308-316 doi: 10.1007/s11465-014-0318-6

摘要:

Human-like torso features are essential in humanoid robots. In this paper problems for design and operation of solutions for a robotic torso are discussed by referring to experiences and designs that have been developed at Laboratory of Robotics and Mechatronics (LARM) in Cassino, Italy. A new solution is presented with conceptual views as waist-trunk structure that makes a proper partition of the performance for walking and arm operations as sustained by a torso.

关键词: humanoid robots     torso design     parallel manipulators (PKM)     conceptual design    

Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

ZHAI Wenjie, LIU Changxiong, LIANG Yingchun

《机械工程前沿(英文)》 2008年 第3卷 第4期   页码 441-448 doi: 10.1007/s11465-008-0074-6

摘要: By keeping a pad moving relative to a wafer along a circular path without rotation, we developed a polishing technique called circular-translational-moving polishing (CTMP), which permits multidirectional polishing of the work piece and thus bears the advantage of isotropic polishing and a potential increase of material removal rate (MRR) on the wafer. To illuminate the mechanisms of CTMP and determine the optimum process variables in a CTMP process, a three-dimensional hydrodynamic lubrication model for CTMP with a smooth and rigid pad under a quasi-stable state is established in a polar coordinate system. The model equations are further calculated numerically by the finite difference method. The instantaneous distribution of fluid pressure is obtained, which shows that a negative pressure exists. The reason for negative pressure in CTMP and its effect on polishing is discussed. Moreover, the nominal clearance of the fluid film, roll, and pitch angles under different working conditions are obtained in terms of the applied load, moments, and polishing velocity. The obtained numerical analysis can be used as guidance for choosing operation parameters in a practical CTMP application.

关键词: numerical analysis     practical CTMP     circular-translational-moving polishing     CTMP     different    

作为免疫疗法靶点的FOXP3及其辅因子 Review

Yasuhiro Nagai,Lian Lam,Mark I. Greene,Hongtao Zhang

《工程(英文)》 2019年 第5卷 第1期   页码 115-121 doi: 10.1016/j.eng.2019.01.001

摘要:

叉头框蛋白P3(FOXP3)是调节性T细胞(Tregs)的一个主要调节因子,调节性T细胞是能抑制抗原特异性免疫反应的T 细胞亚群,在增强宿主耐受性和维持免疫平衡方面发挥着重要作用。众所周知,FOXP3 与多种蛋白质形成复合物,并能通过乙酰化、磷酸化、泛素化和甲基化等各种翻译后修饰(PTM)进行调节。因此,翻译后修饰可改变FOXP3 的稳定性及其调节基因表达的能力,并最终影响调节性T细胞活性。虽然FOXP3 自身并非理想的药物靶点,但脱乙酰酶、乙酰转移酶、激酶和其他可调节FOXP3 的翻译后修饰的酶均为调控FOXP3 和调节性T细胞活性的潜在靶点。但FOXP3 并非这些酶的唯一底物;因此,当使用相关抑制剂时,必须考虑是否存在有害的“FOXP3脱靶”副作用。

关键词: 调节性T细胞     叉头框蛋白P3(FOXP3    翻译后修饰     自体免疫     癌症    

Bone metastasis of hepatocellular carcinoma: facts and hopes from clinical and translational perspectives

《医学前沿(英文)》 2022年 第16卷 第4期   页码 551-573 doi: 10.1007/s11684-022-0928-z

摘要: Patients with hepatocellular carcinoma (HCC) and bone metastasis (BM) suffer from greatly reduced life quality and a dismal prognosis. However, BM in HCC has long been overlooked possibly due to its relatively low prevalence in previous decades. To date, no consensus or guidelines have been reached or formulated for the prevention and management of HCC BM. Our narrative review manifests the increasing incidence of HCC BM to sound the alarm for additional attention. The risk factors, diagnosis, prognosis, and therapeutic approaches of HCC BM are detailed to provide a panoramic view of this disease to clinicians and specialists. We further delineate an informative cancer bone metastatic cascade based on evidence from recent studies and point out the main factors responsible for the tumor-associated disruption of bone homeostasis and the formation of skeletal cancer lesions. We also present the advances in the pathological and molecular mechanisms of HCC BM to shed light on translational opportunities. Dilemmas and challenges in the treatment and investigation of HCC BM are outlined and discussed to encourage further endeavors in the exploration of underlying pathogenic and molecular mechanisms, as well as the development of novel effective therapies for HCC patients with BM.

关键词: HCC     bone     osteotropism     clinical     basic researches     advances    

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 435-450 doi: 10.1007/s11465-021-0630-x

摘要: Seven-degree-of-freedom redundant manipulators with link offset have many advantages, including obvious geometric significance and suitability for configu-ration control. Their configuration is similar to that of the experimental module manipulator (EMM) in the Chinese Space Station Remote Manipulator System. However, finding the analytical solution of an EMM on the basis of arm angle parameterization is difficult. This study proposes a high-precision, semi-analytical inverse method for EMMs. Firstly, the analytical inverse kinematic solution is established based on joint angle parameterization. Secondly, the analytical inverse kinematic solution for a non-offset spherical–roll–spherical (SRS) redundant manipulator is derived based on arm angle parameterization. The approximate solution of the EMM is calculated in accordance with the relationship between the joint angles of the EMM and the SRS manipulator. Thirdly, the error is corrected using a numerical method through the analytical inverse solution based on joint angle parameterization. After selecting the stride and termination condition, the precise inverse solution is computed for the EMM based on arm angle parameterization. Lastly, case solutions confirm that this method has high precision, and the arm angle parameterization method is superior to the joint angle parameterization method in terms of parameter selection.

关键词: 7-DOF redundant manipulator     inverse kinematics     semi-analytical     arm angle     link offset    

Precision control system of two-DOF stage with linear ultrasonic motor

ZHANG Hanlei, SHI Yunlai, ZHAO Chunsheng

《机械工程前沿(英文)》 2008年 第3卷 第4期   页码 421-425 doi: 10.1007/s11465-008-0063-9

摘要: Using an appropriate control method, linear ultrasonic motors can be used in applications requiring high position accuracy. In this paper, a closed loop PI control system is designed to achieve high position accuracy during the control of a two-DOF stage driven by linear ultrasonic motors. Two ultrasonic motors are mounted on the stage to generate motion in two orthogonal directions. The PI control algorithm is used to increase the stability and accuracy of position control. The -axis mover covers 30 mm forward and backward in less than 0.3 s settling time and the -axis mover in less than 0.4 s. Experimental results denote that the control strategy proposed in this paper appears to have high efficiency, quick response, and high accuracy.

关键词: settling     position accuracy     PI control     control algorithm     orthogonal    

Reverse driving character of 2-DOF closed chain haptic device

GUO Wei-dong, GUO Xin, ZHANG Yu-ru

《机械工程前沿(英文)》 2006年 第1卷 第3期   页码 356-359 doi: 10.1007/s11465-006-0029-8

摘要: Reverse driving character plays an important role in evaluating the performance of a haptic device, and it is the primary rule in the mechanical design. This article mainly investigates the problem of 2-DOF haptic device design f

Conceptual design of compliant translational joints for high-precision applications

Guangbo HAO,Haiyang LI,Xiuyun HE,Xianwen KONG

《机械工程前沿(英文)》 2014年 第9卷 第4期   页码 331-343 doi: 10.1007/s11465-014-0321-y

摘要:

Compliant translational joints (CTJs) have been extensively used in precision engineering and microelectromechanical systems (MEMS). There is an increasing need for designing higher-performance CTJs. This paper deals with the conceptual design of CTJs via three approaches: parallelogram based method, straight-line motion mechanism based method and combination based method. Typical emerging CTJ designs are reviewed by explaining their design principles and qualitatively analyzing their characteristics. New CTJs are proposed using three approaches, including an asymmetric double parallelogram mechanism with slaving mechanism, several compact and symmetric double parallelogram mechanisms with slaving mechanisms and a general CTJ using the center drift compensation and a CTJ using Roberts linkage and several combination designs. This paper provides an overview of the current advances/progresses of CTJ designs and lays the foundation for further optimization, quantitative analysis and characteristic comparisons.

关键词: compliant mechanisms     translational joints     conceptual design     parallelogram     straight-line motion     combination method    

Dendritic cell vaccines in cancer immunotherapy: from biology to translational medicine

Hongmei Xu, Xuetao Cao

《医学前沿(英文)》 2011年 第5卷 第4期   页码 323-332 doi: 10.1007/s11684-011-0172-4

摘要:

A method to calculate working capacity space of multi-DOF manipulator and the application in excavating

Baochen WEI, Feng GAO

《机械工程前沿(英文)》 2012年 第7卷 第2期   页码 109-119 doi: 10.1007/s11465-012-0323-6

摘要:

Working capacity refers to the velocity output and force output of a manipulator. It is usually be represented by output capacity space. In this paper, the method of Linear Programming and a geometric method are proposed to calculate working capacity spaces in different situations. With the consideration of gravity effect of every component, the output force capacity space of heavy duty manipulators is calculated. The results show that the effect of the gravity is a translation of the capacity space. This paper gives a method for the output capacity express especially for heavy duty manipulators. The output capacity space can be helpful to the driving parameters selection. With the consideration of the gravity effect of every component and the friction at the joints, the excavating force capacity space of the heavy-load excavating mechanism is calculated and is represented as a multi-dimensional polytope. The results show that the effect of the gravity and friction is to translational act on the capacity space.

关键词: working capacity     multi-DOF manipulator     capacity polytope     excavating mechanism    

One DOF mechanism for the mechanical harvest of vines in an arbor structure and the validation of the

Osvaldo PENISI,José BOCCA,Horacio AGUILAR,Pedro BOCCA

《机械工程前沿(英文)》 2015年 第10卷 第3期   页码 221-232 doi: 10.1007/s11465-015-0347-9

摘要:

In the mechanized harvest of vines, grape berries are detached through the vibration to the structure supporting the clusters. According to the kind of guide selected, the clusters require one or two vibration directions in the structure. For guiding in parral structures, vibration is necessary in two directions or planes: One perpendicular to the other. The guide branches producing the clusters develop in these planes, and the guiding is called H-guiding. Mechanism theory indicates that a mechanism has as many degrees of freedom as its actuators, and an actuator is needed to achieve a certain vibration. Having the smallest number of possible actuators is beneficial in reducing moving parts and achieving more compact and easily controllable mecha-nisms. In this case, a single degree-of-freedom mechanism is proposed. It is capable of generating vibrations on two planes: One perpendicular to the other. This mechanism is the sum of two link mechanisms on perpendicular planes with a common outlet located at the output rod of the mechanism where the actuator is found. As the distance between the soil and the elements containing the clusters is not constant, a system has been designed to measure the accelerations at the bars and the rocker to validate the acceleration values that detach the grape berries in a prototype in a lab experiment, to ensure that the acceleration needed for pulling the grape berries are produced at any contact point of the bar.

关键词: harvest     mechanisms     one DOF     vibration    

Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

《机械工程前沿(英文)》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0695-1

摘要: This study presents a family of novel translational parallel mechanisms (TPMs) with single-loop topological structures. The proposed mechanism consists of only revolute and prismatic joints. The novel TPMs are simpler in structure and have fewer joints and components than the well-known Delta Robot. Four types of 2-degree of freedom driving systems are applied to different limb structures to avoid the moving actuator that causes the problem of increased moving mass. Four sample TPMs are constructed using the synthesized limbs, and one of them is investigated in terms of kinematic performance. First, a position analysis is performed and validated through numerical simulation to reveal the characteristics of partially decoupled motion, which improves the controllability of TPM. Second, singular configurations are identified, and the resulting singularity curve is obtained. Lastly, the workspace of TPM is analyzed, and the relationship between the singular configurations and the reachable workspace is explored. The workspace of the 3-CRR (C denotes the cylindrical joint and R denotes the revolute joint) translational mechanism is also presented to prove that the proposed TPM has a fairly large workspace.

关键词: translational parallel mechanism     single loop     multiple driving system     workspace analysis     singularity    

标题 作者 时间 类型 操作

Stiffness of a 3-degree of freedom translational parallel kinematic machine

null

期刊论文

Manufacturing error analysis of compliant 3-DOF microrobot

CHAO Dai-hong, LIU Rong, WU Yue-min, SHI Long, ZONG Guang-hua

期刊论文

Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine

null

期刊论文

LARM PKM solutions for torso design in humanoid robots

Marco CECCARELLI

期刊论文

Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

ZHAI Wenjie, LIU Changxiong, LIANG Yingchun

期刊论文

作为免疫疗法靶点的FOXP3及其辅因子

Yasuhiro Nagai,Lian Lam,Mark I. Greene,Hongtao Zhang

期刊论文

Bone metastasis of hepatocellular carcinoma: facts and hopes from clinical and translational perspectives

期刊论文

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

期刊论文

Precision control system of two-DOF stage with linear ultrasonic motor

ZHANG Hanlei, SHI Yunlai, ZHAO Chunsheng

期刊论文

Reverse driving character of 2-DOF closed chain haptic device

GUO Wei-dong, GUO Xin, ZHANG Yu-ru

期刊论文

Conceptual design of compliant translational joints for high-precision applications

Guangbo HAO,Haiyang LI,Xiuyun HE,Xianwen KONG

期刊论文

Dendritic cell vaccines in cancer immunotherapy: from biology to translational medicine

Hongmei Xu, Xuetao Cao

期刊论文

A method to calculate working capacity space of multi-DOF manipulator and the application in excavating

Baochen WEI, Feng GAO

期刊论文

One DOF mechanism for the mechanical harvest of vines in an arbor structure and the validation of the

Osvaldo PENISI,José BOCCA,Horacio AGUILAR,Pedro BOCCA

期刊论文

Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

期刊论文