Geometric Constraint-based Reconfiguration and Self-motions of a 4-CRU Parallel Mechanism

2021 ◽  
pp. 1-21
Author(s):  
Latifah Nurahmi ◽  
Pradiktio Putrayudanto ◽  
Guowu Wei ◽  
Sunil K. Agrawal
Keyword(s):  
Parallel Mechanism ◽  
New Technology ◽  
Operation Mode ◽  
Geometric Constraints ◽  
Geometric Constraint ◽  
Primary Decomposition ◽  
Sustainable Housing ◽  
Additional Mode ◽  
Moving Platform ◽  
Self Motion

Abstract This paper aims to investigate the reconfiguration and self-motions of a 4-CRU parallel mechanism based on the mechanism geometric constraints. The targeted application of such mechanism in this research is for 3D-printing buildings of multi-directional nozzle as a new technology for constructing sustainable housing. By using primary decomposition, four geometric constraints are identified and the reconfiguration analysis is carried out in each of these. It reveals that each geometric constraint will have three distinct operation modes, namely Schoenflies mode, reversed Schoenflies mode and an additional mode. The additional mode can be either 4-DOF mode or it degenerates into 3-DOF mode, depending on the type of the geometric constraint. By taking into account the actuation and constraint singularities, the workspace of each operation mode is analysed and geometrically illustrated. It allows us to determine the regions in which the reconfiguration takes place. Furthermore, the moving-platform can still perform at least 1-DOF self-motion. It occurs at two specific actuated leg lengths. Demonstration of reconfiguration process and self-motions are also provided through a mock-up prototype.

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.

Reconfiguration of a 3-(rR)PS Metamorphic Parallel Mechanism Based on Complete Workspace and Operation Mode Analysis

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Latifah Nurahmi ◽  
Dongming Gan
Keyword(s):  
Parallel Mechanism ◽  
Operation Mode ◽  
Mode Analysis ◽  
Finite Point ◽  
Constraint Equations ◽  
Revolute Joints ◽  
Operation Modes ◽  
Identification Approach ◽  
Moving Platform ◽  
Mode A

Abstract This paper focuses on the reconfiguration of a 3-(rR)PS metamorphic parallel mechanism based on complete workspace and operation mode analysis. The mechanism consists of three (rR)PS legs, and each (rR) joint is composed of two perpendicular revolute joints. One of the (rR) joint axes can be reconfigured continuously, which allows the mechanism to exhibit three distinct configurations. Initially, the constraint equations are derived by using algebraic geometry approach, and the primary decomposition is computed for the three configurations. It reveals that the 3-(rR)PS metamorphic parallel mechanism can exhibit one up to two operation modes among three configurations. When the second axes of the three (rR) joints intersect at a finite point and not coplanar, the 3-(rR)PS metamorphic parallel mechanism has only one operation mode. If the second axes of the three (rR) joints are coplanar, the 3-(rR)PS metamorphic parallel mechanism has two operation modes. It is shown that both operation modes have the same motion type, namely, 1T2R motion. However, to realize the same trajectories in both operation modes, the moving platform will have different orientations. Hence, the orientation workspaces of both operation modes are characterized and the axodes are used to compare the instantaneous motion of the moving platform when passing through the same trajectories. Based on these results, an identification approach is introduced to identify which operation mode a given mechanism pose belongs to and this provides a useful method for trajectory planning.

Workspace Transition of 3-rRPS Metamorphic Parallel Mechanism in Hyperboloid Configuration

2018 ◽  
Author(s):  
Latifah Nurahmi ◽  
Dongming Gan
Keyword(s):  
Algebraic Geometry ◽  
Parallel Mechanism ◽  
Primary Decomposition ◽  
Revolute Joint ◽  
Reachable Workspace ◽  
Moving Platform ◽  
Rotational Motions

This paper deals with the workspace transition of the 3-rRPS metamorphic parallel mechanism in Hyperboloid configuration. The 3-rRPS metamorphic parallel mechanism is composed of three rRPS legs in which rR joint is reconfigurable. The reconfigurable rR joint allows the moving platform to switch into different Hyperboloid configurations. Two reconfiguration strategies of the mechanism are discussed. In Hyperboloid configurations, the three revolute joint axes are skew and are not parallel to the same plane. These axes can be set with any value within 0° and 90°. By using algebraic geometry approach and Euler parametrization, the workspace of the mechanism is characterized. This workspace is defined as point reachable workspace of any point on the moving platform. The shape of the workspace changes depending on the value of joint parameter angle ϕ. The primary decomposition is computed and it reveals that the 3-rRPS metamorphic parallel mechanism in Hyperboloid configurations can perform 3-dof coupled motions in which the translational motions are completely dependent on the rotational motions.

Dynamic Analysis of the 3-RRPS Metamorphic Parallel Mechanism Based on Instantaneous Screw Axis

2019 ◽  
Author(s):  
Latifah Nurahmi ◽  
Dongming Gan
Keyword(s):  
Dynamic Analysis ◽  
Parallel Mechanism ◽  
Operation Mode ◽  
Translational Motion ◽  
Time Derivative ◽  
Screw Axis ◽  
Operation Modes ◽  
Instantaneous Screw Axis ◽  
Moving Platform ◽  
Instantaneous Screw

Abstract The 3-rRPS metamorphic parallel mechanism can change its configurations thanks to the reconfigurable (rR) joint. The analysis in this paper will focus on one specific configuration where the moving-platform is able to perform 2-dof coupled rotational motions and 1-dof translational motion, which is well-known as 1T2R motion. In this configuration, the mechanism has two types of operation modes, i.e. x0 = 0 and x3 = 0, which have been extensively studied by many researchers. However, the dynamic behaviours of the mechanism in those two operation modes have not been studied. Accordingly, this paper presents the dynamic analysis of the 3-rRPS metamorphic parallel mechanism in both operation modes based on the Instantaneous Screw Axis (ISA). The types of operation mode are initially characterized by means of Euler-Quaternion parameters. The time derivative of transformation matrix is performed in each operation mode and the ISA can be determined. By using the ISA, velocities and accelerations of all points on the moving-platform can be evaluated, which become the foundation of the dynamic analysis in this paper. This approach can be applied to parallel mechanisms having multiple operation modes of different mobility.

scholarly journals Constraint and Mobility Change Analysis of Rubik’s Cube-inspired Reconfigurable Joints and Corresponding Parallel Mechanisms

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Duanling Li ◽  
Pu Jia ◽  
Jiazhou Li ◽  
Dan Zhang ◽  
Xianwen Kong
Keyword(s):  
Parallel Mechanism ◽  
Unique Feature ◽  
Theoretical Method ◽  
Geometric Constraint ◽  
Parallel Mechanisms ◽  
Change Analysis ◽  
Application Range ◽  
And Topology ◽  
Physical Experiments ◽  
Underlying Principle

Abstract The current research of reconfigurable parallel mechanism mainly focuses on the construction of reconfigurable joints. Compared with the method of changing the mobility by physical locking joints, the geometric constraint has good controllability, and the constructed parallel mechanism has more configurations and wider application range. This paper presents a reconfigurable axis (rA) joint inspired and evolved from Rubik's Cubes, which have a unique feature of geometric and physical constraint of axes of joint. The effectiveness of the rA joint in the construction of the limb is analyzed, resulting in a change in mobility and topology of the parallel mechanism. The rA joint makes the angle among the three axes inside the groove changed arbitrarily. This change in mobility is completed by the case illustrated by a 3(rA)P(rA) reconfigurable parallel mechanism having variable mobility from 1 to 6 and having various special configurations including pure translations, pure rotations. The underlying principle of the metamorphosis of this rA joint is shown by investigating the dependence of the corresponding screw system comprising of line vectors, leading to evolution of the rA joint from two types of spherical joints to three types of variable Hooke joints and one revolute joint. The reconfigurable parallel mechanism alters its topology by rotating or locking the axis of rA joint to turn all limbs into different phases. The prototype of reconfigurable parallel mechanism is manufactured and all configurations are enumerated to verify the validity of the theoretical method by physical experiments.

KINEMATICS AND WORKSPACE ANALYSIS OF A 3 DEGREE OF FREEDOM PARALLEL MECHANISM WITH PARALLELOGRAM LINKAGE

2017 ◽  
Vol 41 (5) ◽  
pp. 922-935
Author(s):  
HongJun San ◽  
JunSong Lei ◽  
JiuPeng Chen ◽  
ZhengMing Xiao ◽  
JunJie Zhao
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Analytical Method ◽  
Theoretical Basis ◽  
Parallel Mechanism ◽  
Graphical Method ◽  
Degree Of Freedom ◽  
Workspace Analysis ◽  
Fixed Base ◽  
Moving Platform

In this paper, a 3-DOF translational parallel mechanism with parallelogram linkage was studied. According to the space vector relation between the moving platform and the fixed base, the direct and inverse position solutions of this mechanism was deduced through analytical method. In addition, the error of the algorithm was analyzed, and the algorithm had turned out to be effective and to have the satisfactory computational precision. On the above basis, the workspace of this mechanism was found through graphical method, which was compared with that of finding through Monte Carlo method, and there was the feasibility for analyzing the workspace of the mechanism by graphical method. The characteristic of the mechanism was analyzed by comparing the results of two analysis methods, which provided a theoretical basis for the application of the mechanism.

Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

The Parallel Mechanism and Variable Acceleration Control Method

2013 ◽  
Vol 579-580 ◽  
pp. 659-664
Author(s):  
Xiang Bo Ouyang ◽  
Ke Tian Li ◽  
Hong Jian Xia ◽  
Su Juan Wang ◽  
Huan Wei Zhou ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Control Method ◽  
The Other ◽  
Connecting Rod ◽  
Motion Platform ◽  
The Third ◽  
Symmetric Structure ◽  
Slide Block ◽  
Operation Process ◽  
Moving Platform

t presents the parallel mechanism and variable acceleration control method, which is composed of slider, connecting rod, moving platform and linear guide etc. The motion platform is supported by three connecting rods through hinging, the other end of the connecting rods are respectively hinged with two sliders. Among them two pairs of connecting rod, two sliders and the moving platform formed a symmetric structure that is the so called Parallel Mechanism. The third connecting rod is parallel to one of two connecting rods, so that the two parallel connecting rods, slide block and the moving platform formed a parallelogram structure, it makes that the moving platform is always parallel to liner guiderail in the process of movement. By controlling the two sliders moving in the way of variable acceleration, it can make the trajectory curve, speed curve and acceleration curve of the moving platform are continuous, smooth, so impact and vibration of the moving platform is limited in the operation process.

scholarly journals Research on the Management System of Science and Technology Incubator

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Fang Wang
Keyword(s):  
Management System ◽  
New Technology ◽  
Rapid Development ◽  
Science And Technology ◽  
Operation Mode ◽  
The United States ◽  
Scientific Development ◽  
The World ◽  
Technology Incubator ◽  
Technology Incubators

Science and technology incubator, as an organization dedicated to serving science and technology enterprises, has many functions, such as cultivating small and medium-sized science and technology enterprises, transforming science and technology into productivity, adjusting regional and national industrial structure, promoting the development of high and new technology industries, and promoting employment. Since the emergence of the first business incubator in the United States in the 1950s, this new form of social and economic organization has been developing rapidly all over the world, and has cultivated a large number of successful enterprises, which initially made great contributions to promoting the development of the world economy. However, with the increasing number of science and technology incubators and the rapid development of science and technology enterprises, various problems in the management system and operation mode of science and technology incubators are gradually exposed, which seriously affects the sustainable development of science and technology incubators in China. In view of this, based on the analysis of the current situation of science and technology incubator management in China, this paper puts forward the construction strategy of standardized management system of science and technology incubator in order to promote the scientific development of science and technology incubator in China.

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