Coupling Degree of Mechanism and Its Application

2006 ◽  
Author(s):  
Jing Xiong ◽  
Ting-Li Yang ◽  
Xiangdong Yang ◽  
Dongchao Yang ◽  
Ken Chen
Keyword(s):  
Dynamic Analysis ◽  
Topological Structure ◽  
Parallel Mechanism ◽  
Kinematics And Dynamics ◽  
Parallel Mechanisms ◽  
Kinematic Chains ◽  
Unified Modeling

The kinematic and dynamic analysis of an spatial multi-loop mechanism especially parallel mechanism is significant but always complex. Based on the topological structure of mechanisms, this paper proposes the concept of coupling degree of mechanism systematically, and applies it to the criterion of basic kinematic chains(BKCs) and other problems. The relation between topology, kinematics and dynamics of parallel mechanisms is established, and then it is achieved to quantitatively describe the analysis complexity of a parallel mechanism and to obtain its simplest solving path, according to its topological structure. The preliminary method for unified modeling of the topology, kinematics and dynamics of parallel mechanisms is proposed, using BKC as the basic analysis unit. Some suggestions for optimization and selective preference of parallel mechanisms are also presented.

scholarly journals Design of Self-Reconfigurable Multiarm Robot Mechanism Based on Deployable Kinematic Chains

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Fu-Qun Zhao ◽  
Sheng Guo ◽  
Hai-Jun Su ◽  
Hai-Bo Qu ◽  
Ya-Qiong Chen
Keyword(s):  
Parallel Mechanism ◽  
Parallel Mechanisms ◽  
Kinematic Chains ◽  
Assembly Method ◽  
Operation Modes ◽  
Object Based ◽  
Switch Operation ◽  
Storage Area ◽  
Mechanism Theory

Abstract As the structures of multiarm robots are serially arranged, the packaging and transportation of these robots are often inconvenient. The ability of these robots to operate objects must also be improved. Addressing this issue, this paper presents a type of multiarm robot that can be adequately folded into a designed area. The robot can achieve different operation modes by combining different arms and objects. First, deployable kinematic chains (DKCs) are designed, which can be folded into a designated area and be used as an arm structure in the multiarm robot mechanism. The strategy of a platform for storing DKCs is proposed. Based on the restrictions in the storage area and the characteristics of parallel mechanisms, a class of DKCs, called base assembly library, is obtained. Subsequently, an assembly method for the synthesis of the multiarm robot mechanism is proposed, which can be formed by the connection of a multiarm robot mechanism with an operation object based on a parallel mechanism structure. The formed parallel mechanism can achieve a reconfigurable characteristic when different DKCs connect to the operation object. Using this method, two types of multiarm robot mechanisms with four DKCs that can switch operation modes to perform different tasks through autonomous combination and release operation is proposed. The obtained mechanisms have observable advantages when compared with the traditional mechanisms, including optimizing the occupied volume during transportation and using parallel mechanism theory to analyze the switching of operation modes.

scholarly journals Reconfiguration Analysis of a 3-DOF Parallel Mechanism

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 66
Author(s):  
Maurizio Ruggiu ◽  
Xianwen Kong
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Operation Mode ◽  
Parallel Mechanisms ◽  
Universal Joint ◽  
Kinematic Chains ◽  
Constraint Equations ◽  
The Third ◽  
Equilateral Triangles ◽  
Moving Platform

This paper deals with the reconfiguration analysis of a 3-DOF (degrees-of-freedom) parallel manipulator (PM) which belongs to the cylindrical parallel mechanisms family. The PM is composed of a base and a moving platform shaped as equilateral triangles connected by three serial kinematic chains (legs). Two legs are composed of two universal (U) joints connected by a prismatic (P) joint. The third leg is composed of a revolute (R) joint connected to the base, a prismatic joint and universal joint in sequence. A set of constraint equations of the 1-RPU−2-UPU PM is derived and solved in terms of the Euler parameter quaternion (a.k.a. Euler-Rodrigues quaternion) representing the orientation of the moving platform and of the Cartesian coordinates of the reference point on the moving platform. It is found that the PM may undergo either the 3-DOF PPR or the 3-DOF planar operation mode only when the base and the moving platform are identical. The transition configuration between the operation modes is also identified.

Position and Orientation Characteristic Equation for Topological Design of Parallel Mechanisms

2008 ◽  
Author(s):  
Ting-Li Yang ◽  
An-Xin Liu ◽  
Qiong Jin ◽  
Yu-Feng Luo ◽  
Hui-Ping Shen ◽  
...  
Keyword(s):  
Topological Structure ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Output Link ◽  
Geometrical Meaning ◽  
Operation Rules ◽  
The Matrix ◽  
Position And Orientation ◽  
Symbolic Operation

This paper presents the explicit mapping relations between topological structure of parallel mechanism and position and orientation characteristic (in short, POC) of its motion output link. It deals with: (1) The symbolic representation and the invariant of topological structure of mechanism; (2) The matrix representation of POC of motion output link; (3) The POC equations of parallel mechanism and its symbolic operation rules. The symbolic operation involves simple mathematic tools and fewer operation rules, and has clear geometrical meaning. So, it is easy to use. The forward operation of the POC equations can be used for structural analysis; its inverse operation can be used for structural synthesis. The method proposed in this paper is totally different from the methods based on screw theory and based on displacement subgroup.

Compositional Submanifolds of Prismatic–Universal–Prismatic and Skewed Prismatic–Revolute– Prismatic Kinematic Chains and Their Derived Parallel Mechanisms

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Xinsheng Zhang ◽  
Pablo López-Custodio ◽  
Jian S. Dai
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Chain ◽  
Planar Motion ◽  
Helical Motion ◽  
Parallel Mechanisms ◽  
Motion Group ◽  
Revolute Joint ◽  
Kinematic Chains ◽  
Prismatic Joint ◽  
Joint Axis

The kinematic chains that generate the planar motion group in which the prismatic-joint direction is always perpendicular to the revolute-joint axis have shown their effectiveness in type synthesis and mechanism analysis in parallel mechanisms. This paper extends the standard prismatic–revolute–prismatic (PRP) kinematic chain generating the planar motion group to a relatively generic case, in which one of the prismatic joint-directions is not necessarily perpendicular to the revolute-joint axis, leading to the discovery of a pseudo-helical motion with a variable pitch in a kinematic chain. The displacement of such a PRP chain generates a submanifold of the Schoenflies motion subgroup. This paper investigates for the first time this type of motion that is the variable-pitched pseudo-planar motion described by the above submanifold. Following the extraction of a helical motion from this skewed PRP kinematic chain, this paper investigates the bifurcated motion in a 3-prismatic–universal–prismatic (PUP) parallel mechanism by changing the active geometrical constraint in its configuration space. The method used in this contribution simplifies the analysis of such a parallel mechanism without resorting to an in-depth geometrical analysis and screw theory. Further, a parallel platform which can generate this skewed PRP type of motion is presented. An experimental test setup is based on a three-dimensional (3D) printed prototype of the 3-PUP parallel mechanism to detect the variable-pitched translation of the helical motion.

A decoupled 2-DOF flexure-based micropositioning stage with large travel ranges

Robotica ◽  
2013 ◽  
Vol 32 (5) ◽  
pp. 677-694 ◽  
Author(s):  
Xiantao Sun ◽  
Weihai Chen ◽  
Rui Zhou ◽  
Wenjie Chen ◽  
Jianbin Zhang
Keyword(s):  
Topological Structure ◽  
Natural Frequencies ◽  
Mechanical Performance ◽  
Theoretical Models ◽  
Kinematics And Dynamics ◽  
Dynamics Analysis ◽  
Kinematic Chains ◽  
Element Simulation ◽  
Prismatic Joints ◽  
Coupling Error

SUMMARYIn this paper, a new flexure-based micropositioning stage (FMPS) is proposed to achieve decoupled XY translational motions and large travel ranges. The stage consists of four independent kinematic chains, each comprising two flexure-beam prismatic joints. The mechanism with such a special topological structure enables the motions of the platform strictly along XY axes and minimizes the parasitic rotation in theta axis. The kinematics and dynamics analysis of the mechanism are conducted to evaluate the performance of the mechanism in terms of travel range, parasitic motions, linearity, as well as natural frequency. According to the developed models, a parameter optimization of the mechanism is performed under the condition of the maximum travel range. The finite element simulation is carried out to examine the mechanical performance and the theoretical models. The experimental results show that the proposed FMPS possesses a workspace of 600 × 600 μm2, a relative coupling error of 0.6%, and the natural frequencies of 209.7 Hz and 212.4 Hz for the first two modes.

Comprehensive Evaluation of Parallel Mechanism and Robot Performance Based on Principal Component Analysis and Kernel Principal Component Analysis

2015 ◽  
Author(s):  
Liming Li ◽  
Jing Zhao
Keyword(s):  
Principal Component Analysis ◽  
Dimension Reduction ◽  
Topological Structure ◽  
Parallel Mechanism ◽  
Principal Component ◽  
Component Analysis ◽  
Kernel Principal Component Analysis ◽  
Parallel Mechanisms ◽  
Performance Indexes ◽  
Comprehensive Performance

Revealing the relations among parallel mechanism and robot comprehensive performance, topological structure and dimension is the basis to optimize mechanism. Due to the correlation and diversity of the single performance indexes, statistical principles of linear dimension reduction and nonlinear dimension reduction were introduced into comprehensive performance analysis and evaluation for typical parallel mechanisms and robots. Then the mechanism’s topological structure and dimension with the best comprehensive performance could be selected based on principal component analysis (PCA) and kernel principal component analysis (KPCA) respectively. Through comparing the results, KPCA could reveal the nonlinear relationship among different single performance indexes to provide more comprehensive performance evaluation information than PCA, and indicate the numerical calculation relations among comprehensive performance, topological structure and dimension validly.

The Creative Design of Injector Clamping Mechanism

2011 ◽  
Vol 418-420 ◽  
pp. 2166-2169
Author(s):  
Wan Chun Zhou ◽  
Dong Min Liu
Keyword(s):  
Topological Structure ◽  
Kinematic Chain ◽  
Kinematics And Dynamics ◽  
Dynamics Analysis ◽  
Connecting Rod ◽  
Design Constraints ◽  
Kinematic Chains ◽  
Structure Characteristics ◽  
Comprehensive Theory ◽  
Design Requirements

Abstract. Analysis of a certain topological structure characteristics of clamping mechanism of injection machine, according to general principles, converts it into only containing Deputy General of the connecting rod and rotating chain. Bodies comprehensive theory of numbers after distribution combined with rod classes are general Atlas of kinematic chain. After identifying design constraints, on the redistribute members and turn the pair, you can get all man foot design requirements of viable specific Atlas of kinematic chains. Then every possible specific kinematic chain materialized to the schematic diagram of mechanism. Designers are on this basis through the kinematics and dynamics analysis to determine the best new clamping mechanism of injection machine.

A serial of novel four degrees of freedom parallel mechanisms with large rotational workspace

Robotica ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 764-776 ◽  
Author(s):  
Sheng Guo ◽  
Wei Ye ◽  
Haibo Qu ◽  
Dan Zhang ◽  
Yuefa Fang
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Planetary Gear ◽  
Gear Train ◽  
Parallel Mechanisms ◽  
Kinematics Analysis ◽  
Kinematic Chains ◽  
Moving Platform ◽  
Partition Method

SUMMARYIn this paper, a class of novel four Degrees of Freedom (DOF) non-overconstrained parallel mechanisms with large rotational workspace is presented based on screw theory. First, the conflict between the number of independent constraints applied on the moving platform and the number of kinematic limbs for 4-DOF non-overconstrained parallel mechanism is identified. To solve this conflict, the platform partition method is introduced, and two secondary platforms are employed in each of the parallel mechanisms. Then, the motion requirements of the secondary platforms are analyzed and all the possible kinematic chains are enumerated. The geometrical assembly conditions of all possible secondary limbs are analyzed and some typical non-overconstrained parallel mechanisms are generated. In each of the parallel mechanisms, a planetary gear train is used to connect both of the secondary platforms. The large rotational workspace of the moving platform is obtained due to the relative motion of the two secondary platforms. Finally, the kinematics analysis of a typical parallel mechanism is conducted.

Lie Group Based Type Synthesis Using Transformation Configuration Space for Reconfigurable Parallel Mechanisms With Bifurcation Between Spherical Motion and Planar Motion

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Jun Wei ◽  
Jian S. Dai
Keyword(s):  
Configuration Space ◽  
Parallel Mechanism ◽  
Identity Element ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Motion Representation ◽  
Kinematic Chains ◽  
Common Intersection ◽  
The Common ◽  
Spherical Motion

Abstract This paper investigates novel reconfigurable parallel mechanisms with bifurcation between planar subgroup SE(2) and rotation subgroup SO(3) based on a transformation configuration space. Having recollected necessary theoretical fundamentals with regard to compositional submanifolds and kinematic bonds, the motion representation of the platform of reconfigurable parallel mechanisms are investigated. The transformation configuration space of a reconfigurable parallel mechanism with motion branches is proposed with respect to the fact that the intersection of Lie subgroups or submanifolds is the identity element or a non-identity element. The switch conditions of the transformation configuration space are discussed, leading to establishment of a theoretical foundation for realizing a switch of motion branches. The switch principle of reconfigurable parallel mechanisms is further investigated with respect to the common motion between SE(2) parallel-mechanism motion generators and SO(3) parallel-mechanism motion generators. Under this principle, the subchains with common motion generators are synthesized and divided into two types of generators. The first type of generators generates kinematic chains with a common intersection of three joint axes, and the second type of generators generates a common intersection of two joint axes. Following this, two types of reconfigurable parallel mechanisms with three identical subchains are synthesized, resulting in 11 varieties in which platforms can be switched between SE(2) and SO(3) after passing through the singularity configuration space.

Dualities in the Analysis of Mechanisms With Multiple Loops and Parallel Mechanisms With Loops in Their Connecting Chains

2004 ◽  
Author(s):  
Koichi Sugimoto
Keyword(s):  
Dynamic Analysis ◽  
Parallel Mechanism ◽  
Jacobian Matrix ◽  
Parallel Mechanisms ◽  
Body System ◽  
Multi Body ◽  
The Relationship

There exists a duality relationship between a twist and a wrench in the dynamics of a mechanism or a multi-body system. Using this relationship, the coordinate-free expressions for the dynamic analysis of multi-loop mechanisms is derived. In the analysis, a Jacobian matrix expressing the relationship among loops is defined, and it is clarified, by using this matrix, that both twists and wrenches can be easily analyzed based on the duality relationship among them. A parallel mechanism having connecting chains with loops is also analyzed, and it is shown that the same procedure can be applied to a parallel mechanism with connecting chains, each loop of which has a motion space that is different from that of the mechanism.

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