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Cusp points and assembly changing motions in the PRR-PR-PRR planar parallel manipulator

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0743-x

摘要: Most parallel manipulators have multiple solutions to the direct kinematic problem. The ability to perform assembly changing motions has received the attention of a few researchers. Cusp points play an important role in the kinematic behavior. This study investigates the cusp points and assembly changing motions in a two degrees of freedom planar parallel manipulator. The direct kinematic problem of the manipulator yields a quartic polynomial equation. Each root in the equation determines the assembly configuration, and four solutions are obtained for a given set of actuated joint coordinates. By regarding the discriminant of the repeated roots of the quartic equation as an implicit function of two actuated joint coordinates, the direct kinematic singularity loci in the joint space are determined by the implicit function. Cusp points are then obtained by the intersection of a quadratic curve and a cubic curve. Two assembly changing motions by encircling different cusp points are highlighted, for each pair of solutions with the same sign of the determinants of the direct Jacobian matrices.

关键词: planar parallel manipulator     assembly changing motions     cusp points     quartic polynomial     discriminant of repeated roots    

Optimal design of a linkage–cam mechanism-based redundantly actuated parallel manipulator

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 451-467 doi: 10.1007/s11465-021-0634-6

摘要: A redundantly actuated parallel manipulator (RAPM) with mixed translational and rotational degrees of freedom (DOFs) is challenged for its dimensionally homogeneous Jacobian modeling and optimal design of architecture. In this paper, a means to achieve redundant actuation by adding kinematic constraints is introduced, which reduces the DOFs of the end-effector (EE). A generic dimensionally homogeneous Jacobian is developed for this type of RAPMs, which maps the generalized velocities of three points on the EE to the joint velocities. A new optimization algorithm derived from this dimensionally homogeneous Jacobian is proposed for the optimal design of this type of RAPMs. As an example, this paper presents a spatial RAPM involving linkages and cam mechanisms. This RAPM has 4 DOFs and 6 translational actuations. The linkage lengths and the position of the universal joints of the RAPM are optimized based on the dimensionally homogeneous Jacobian.

关键词: redundant actuation     parallel manipulator     linkage–cam mechanism     Jacobian     optimal design    

Dynamic modeling of flexible-links planar parallel robots

DU Zhaocai, YU Yueqing, ZHANG Xuping, DU Zhaocai

《机械工程前沿(英文)》 2008年 第3卷 第2期   页码 232-237 doi: 10.1007/s11465-008-0032-3

摘要: This paper presents a finite element-based method for dynamic modeling of parallel robots with flexible links and rigid moving platform. The elastic displacements of flexible links are investigated while considering the coupling effects between links due to the structural flexibility. The kinematic constraint conditions and dynamic constraint conditions for elastic displacements are presented. Considering the effects of distributed mass, lumped mass, shearing deformation, bending deformation, tensile deformation and lateral displacements, the Kineto-Elasto dynamics (KED) theory and Lagrange formula are used to derive the dynamic equations of planar flexible-links parallel robots. The dynamic behavior of the flexible-links planar parallel robot is well illustrated through numerical simulation of a planar 3-RR parallel robot. Compared with the results of finite element software SAMCEF, the numerical simulation results show good coherence of the proposed method. The flexibility of links is demonstrated to have a significant impact on the position error and orientation error of the flexible-links planar parallel robot.

关键词: 3-RR parallel     KED     coupling     software SAMCEF     orientation    

Synthesis of spherical parallel manipulator for dexterous medical task

Abdelbadia CHAKER, Abdelfattah MLIKA, Med Amine LARIBI, Lotfi ROMDHANE, Sa?d ZEGHLOUL

《机械工程前沿(英文)》 2012年 第7卷 第2期   页码 150-162 doi: 10.1007/s11465-012-0325-4

摘要:

This paper deals with the design and the analysis of a spherical parallel manipulator (SPM) for a haptic minimally invasive surgery application. First the medical task was characterized with the help of a surgeon who performed a suture technique called anastomosis. A Vicon system was used to capture the motion of the surgeon, which yielded the volume swept by the tool during the anastomosis operation. The identified workspace can be represented by a cone with a half vertex angle of 26°. A multi objective optimization procedure based on genetic algorithms was then carried out to find the optimal SPM. Two criteria were considered, i.e., task workspace and mechanism dexterity. The optimized SPM was then analyzed to determine the error on the orientation of the end effector as a function of the manufacturing errors of the different links of the mechanism.

关键词: spherical parallel manipulator (SPM)     anastomosis     haptic     motion capture     optimization     workspace     dexterity     genetic algorithm     manufacturing errors    

Motion capability analysis of a quadruped robot as a parallel manipulator

Jingjun YU,Dengfeng LU,Zhongxiang ZHANG,Xu PEI

《机械工程前沿(英文)》 2014年 第9卷 第4期   页码 295-307 doi: 10.1007/s11465-014-0317-7

摘要:

This paper presents the forward and inverse displacement analysis of a quadruped robot MANA as a parallel manipulator in quadruple stance phase, which is used to obtain the workspace and control the motion of the body. The robot MANA designed on the basis of the structure of quadruped mammal is able to not only walk and turn in the uneven terrain, but also accomplish various manipulating tasks as a parallel manipulator in quadruple stance phase. The latter will be the focus of this paper, however. For this purpose, the leg kinematics is primarily analyzed, which lays the foundation on the gait planning in terms of locomotion and body kinematics analysis as a parallel manipulator. When all four feet of the robot contact on the ground, by assuming there is no slipping at the feet, each contacting point is treated as a passive spherical joint and the kinematic model of parallel manipulator is established. The method for choosing six non-redundant actuated joints for the parallel manipulator from all twelve optional joints is elaborated. The inverse and forward displacement analysis of the parallel manipulator is carried out using the method of coordinate transformation. Finally, based on the inverse and forward kinematic model, two issues on obtaining the reachable workspace of parallel manipulator and planning the motion of the body are implemented and verified by ADAMS simulation.

关键词: quadruped robot     actuated joints selection     kinematics analysis     motion planning     parallel manipulator    

Analysis of the dynamic stress of planar flexible-links parallel robots

DU Zhaocai, YU Yueqing, YANG Jianxin

《机械工程前沿(英文)》 2007年 第2卷 第2期   页码 152-158 doi: 10.1007/s11465-007-0025-7

摘要: This paper presents a method for the dynamic stress analysis of planar parallel robots with flexible links and a rigid moving platform. The finite element-based dynamic model of flexible parallel robots is proposed. The relation between elastic deformations and elastic displacements of the flexible links is investigated, considering the coupling effects of elastic motion and rigid motion. The elastic deformations of links are calculated. Considering the effects of bending-shearing strain and tensile-compression strain, the dynamic stress of the links and its position are derived by using the Kineto-Elastodynamics theory and the Timoshenko beam theory. Due to the flexibility of the links, the dynamic stresses are well illustrated through numerical simulation. Compared with the results of the finite element software SAMCEF, the numerical simulation results show the good coherence and advantages of the analysis method. The dynamic stress analysis is demonstrated to have a significant impact on the analysis, design and control of flexible parallel robots.

关键词: numerical simulation     Due     coupling     software SAMCEF     flexibility    

Singularity and workspace analysis of three isoconstrained parallel manipulators with schoenflies motion

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

摘要:

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    

并联构型装备的研究进展及若干关键技术

汪劲松,李铁民,段广洪

《中国工程科学》 2002年 第4卷 第6期   页码 63-70

摘要:

并联构型装备正处于商品化、产业化的关键时期。文章从结构、应用领域、驱动方式、控制等方面阐述了并联构型装备的研究进展,介绍了国际上的一些主要研究计划,分析了产业化进程中的若干关键技术及其可能的解决方案。

关键词: 并联机构     并联构型装备     驱动     控制系统    

A feasibility study on the design and walking operation of a biped locomotor via dynamic simulation

null

《机械工程前沿(英文)》 2016年 第11卷 第2期   页码 144-158 doi: 10.1007/s11465-016-0391-0

摘要:

A feasibility study on the mechanical design and walking operation of a Cassino biped locomotor is presented in this paper. The biped locomotor consists of two identical 3 degrees-of-freedom tripod leg mechanisms with a parallel manipulator architecture. Planning of the biped walking gait is performed by coordinating the motions of the two leg mechanisms and waist. A three-dimensional model is elaborated in SolidWorks® environment in order to characterize a feasible mechanical design. Dynamic simulation is carried out in MSC.ADAMS® environment with the aims of characterizing and evaluating the dynamic walking performance of the proposed design. Simulation results show that the proposed biped locomotor with proper input motions of linear actuators performs practical and feasible walking on flat surfaces with limited actuation and reaction forces between its feet and the ground. A preliminary prototype of the biped locomotor is built for the purpose of evaluating the operation performance of the biped walking gait of the proposed locomotor.

关键词: feasibility study     biped locomotor     biped walking     mechanical design     dynamic simulation     tripod leg mechanism     3-UPU parallel manipulator    

Precision analysis of a weakly-coupled parallel mechanism with three translational degrees of freedom

MA Lv-zhong, GUO Zong-he, YANG Qi-zhi, YIN Xiao-qin, HAN Ya-li, SHEN Hui-ping

《机械工程前沿(英文)》 2006年 第1卷 第2期   页码 227-232 doi: 10.1007/s11465-006-0005-3

摘要: This paper analyzes the precision of the dissymmetrical parallel mechanism of 3-RRRP(4R) with three translational degrees of freedom (DOF). The parallel mechanism has weakly-coupled, decoupled and real-time characteristics, thus error compensation can be done using control software. Based on topology structure analysis, the inverse and forward solutions are analyzed and the precision is studied using complete differential method. The influencing factors of the manipulator s precision are studied carefully and the means to enhance the precision are also discussed. It is found that the position errors of the moving platform have nonlinear relation with the position of the mechanism. The δθ' error has the biggest influence on the nonlinear errors of the position. Otherwise, the original errors of the mechanism are the main reason leading to more errors. Thus enhancing machining and assembling precision is an important method to enhance the precision of the mechanism.

关键词: manipulator     nonlinear     δθ     influence     differential    

Genetic evidence in planar cell polarity signaling pathway in human neural tube defects

null

《医学前沿(英文)》 2014年 第8卷 第1期   页码 68-78 doi: 10.1007/s11684-014-0308-4

摘要:

Neural tube defects (NTDs) are a group of birth anomalies having a profound physical, emotional, and financial effects on families and communities. Their etiology is complex, involving environmental and genetic factors that interact to modulate the incidence and severity of the developing phenotype. The planar cell polarity (PCP) pathway controls the process of convergent extension (CE) during gastrulation and neural tube closure and has been implicated in the pathogenesis of NTDs in animal models and human cohorts. This review summarizes the cumulative results of recent studies on PCP signaling pathway and human NTDs. These results demonstrate that PCP gene alterations contribute to the etiology of human NTDs.

关键词: planar cell polarity     neural tube defects     rare mutations    

Design and analysis of a class of redundant collaborative manipulators with 2-dimension large rotational angles

Xiaodong JIN, Yuefa FANG, Dan ZHANG, Xueling LUO

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 66-80 doi: 10.1007/s11465-019-0570-x

摘要: The parallel spindle heads with high rotational capability are demanded in the area of multi-axis machine tools and 3D printers. This paper focuses on designing a class of 2R1T (R: Rotation; T: Translation) parallel spindle heads and the corresponding collaborative 5-axis manipulators with 2-dimension (2D) large rotational angles. In order to construct 2D rotational degrees of freedom (DOF), a platform with 2-dimension revolute joints is proposed first. Based on the constraint screw theory, the feasible limbs that can be connected in the platform are synthesized. In order to provide constant rotational axis for the platform, a class of redundant limbs are designed. A class of redundant 2R1T parallel spindle heads is obtained by connecting the redundant limbs with the platform and the redundant characteristics are verified by the modified Grübler-Kutzbach criterion. The corresponding 5-axis collaborative manipulators are presented by constructing a 2-DOF series translational bottom moving platform. The inverse kinematics and the orientation workspace as well as the decoupling characteristics of this type of 2R1T parallel spindle heads are analyzed. The results show that these manipulators have large 2D rotational angles than the traditional A3/Z3 heads and can be potentially used in the application of multi-axis machine tools and the 3D printers.

关键词: parallel mechanism     redundant mechanism     large rotational angles     machine tools     2R1T spindle head     collaborative manipulator    

Static balancing of planar articulated robots

Giuseppe QUAGLIA,Zhe YIN

《机械工程前沿(英文)》 2015年 第10卷 第4期   页码 326-343 doi: 10.1007/s11465-015-0355-9

摘要:

Static balancing for a manipulator’s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on robotic dynamics. Full design details for the balancing system using springs are presented from two aspects: One is the optimization for the position of the balancing system; the other is the design of the spring parameters. As examples, two feasible balancing devices are proposed, based on different robotic structures: The first solution consists of linkages and springs; the other consists of pulleys, cross mechanisms and (hydro-) pneumatic springs. Then the two solutions are compared. Pneumatic, hydro-pneumatic and mechanical springs are discussed and their parameters are decided according to the requirements of torque compensation. Numerical results show that with the proper design using the methodology presented in this paper, an articulated robot can be statically balanced perfectly in all configurations. This paper therefore provides a design method of the balancing system for other similar structures.

关键词: robotics     static balancing     pneumatic spring     mechanical spring     torque compensation    

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    

Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll–pitch–yaw spherical

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 698-710 doi: 10.1007/s11465-021-0646-2

摘要: The demand for redundant hydraulic manipulators that can implement complex heavy-duty tasks in unstructured areas is increasing; however, current manipulator layouts that remarkably differ from human arms make intuitive kinematic operation challenging to achieve. This study proposes a seven-degree-of-freedom (7-DOF) redundant anthropomorphic hydraulically actuated manipulator with a novel roll–pitch–yaw spherical wrist. A hybrid series–parallel mechanism is presented to achieve the spherical wrist design, which consists of two parallel linear hydraulic cylinders to drive the yaw/pitch 2-DOF wrist plate connected serially to the roll structure. Designed as a 1R PRRR-1S PU mechanism (“R”, “P”, “S”, and “U” denote revolute, prismatic, spherical, and universal joints, respectively; the underlined letter indicates the active joint), the 2-DOF parallel structure is partially decoupled to obtain simple forward/inverse kinematic solutions in which a closed-loop subchain “R PRR” is included. The 7-DOF manipulator is then designed, and its third joint axis goes through the spherical center to obtain closed-form inverse kinematic computation. The analytical inverse kinematic solution is drawn by constructing self-motion manifolds. Finally, a physical prototype is developed, and the kinematic analysis is validated via numerical simulation and test results.

关键词: hydraulic manipulator     inverse kinematic     redundant design     spherical wrist    

标题 作者 时间 类型 操作

Cusp points and assembly changing motions in the PRR-PR-PRR planar parallel manipulator

期刊论文

Optimal design of a linkage–cam mechanism-based redundantly actuated parallel manipulator

期刊论文

Dynamic modeling of flexible-links planar parallel robots

DU Zhaocai, YU Yueqing, ZHANG Xuping, DU Zhaocai

期刊论文

Synthesis of spherical parallel manipulator for dexterous medical task

Abdelbadia CHAKER, Abdelfattah MLIKA, Med Amine LARIBI, Lotfi ROMDHANE, Sa?d ZEGHLOUL

期刊论文

Motion capability analysis of a quadruped robot as a parallel manipulator

Jingjun YU,Dengfeng LU,Zhongxiang ZHANG,Xu PEI

期刊论文

Analysis of the dynamic stress of planar flexible-links parallel robots

DU Zhaocai, YU Yueqing, YANG Jianxin

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

并联构型装备的研究进展及若干关键技术

汪劲松,李铁民,段广洪

期刊论文

A feasibility study on the design and walking operation of a biped locomotor via dynamic simulation

null

期刊论文

Precision analysis of a weakly-coupled parallel mechanism with three translational degrees of freedom

MA Lv-zhong, GUO Zong-he, YANG Qi-zhi, YIN Xiao-qin, HAN Ya-li, SHEN Hui-ping

期刊论文

Genetic evidence in planar cell polarity signaling pathway in human neural tube defects

null

期刊论文

Design and analysis of a class of redundant collaborative manipulators with 2-dimension large rotational angles

Xiaodong JIN, Yuefa FANG, Dan ZHANG, Xueling LUO

期刊论文

Static balancing of planar articulated robots

Giuseppe QUAGLIA,Zhe YIN

期刊论文

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

期刊论文

Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll–pitch–yaw spherical

期刊论文