A Three-DOF Rotational Parallel Manipulator Without Intersecting Axes

2010 ◽  
Author(s):  
Ziming Chen ◽  
Jingfang Liu ◽  
Zhen Huang
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Revolute Joint ◽  
Rotational Motions ◽  
Orientation Workspace

It is difficult to manufacture parallel manipulators(PMs) with multiple revolute joint axes intersecting at one point. These types include the 3-DOF spherical parallel manipulators (SPMs), the 4-DOF 3R1T and 2R2T PMs, the 5-DOF 3R2T PMs. This problem makes it hard to achieve the expected mobility of these PMs. In this paper, a 3-RPS cubic PM is studied which has three rotational freedoms and no intersecting axes. The orientation workspace of this PM is analyzed. Some discussions about the differences between the traditional SPMs and this PM are proposed. The results show that the 3-RPS cubic PM can achieve three rotational motions and has no intersecting axes.

A 3DOF Rotational Parallel Manipulator Without Intersecting Axes

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Zhen Huang ◽  
Ziming Chen ◽  
Jingfang Liu ◽  
Shichang Liu
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Revolute Joint ◽  
Manufacturing Errors ◽  
Rotational Motions ◽  
Orientation Workspace

It is difficult to manufacture parallel manipulators (PMs) with multiple revolute joint axes intersecting at one point. These types include the 3DOF spherical parallel manipulators (SPMs), the 4DOF 3R1T and 2R2T PMs, the 5DOF 3R2T PMs, etc. PMs with this problem are hard to achieve the expected mobility. In this paper, a 3-RPS cubic PM is studied, which has three rotational freedoms and is without those intersecting axes. The motion property of this PM will not change when the manufacturing errors exist. In order to show its orientation capability, the orientation workspace of this PM is analyzed. More discussions about the differences between the traditional SPMs and this PM are proposed. The results show that compared with the traditional SPMs, this 3-RPS cubic PM can also achieve three rotational motions with an enough orientation capability for applications and it has the advantage of easy fabrication.

Position and Workspace Analyses of 3-SPR and 3-RPS Parallel Manipulators

2005 ◽  
Author(s):  
Yi Lu ◽  
Yonghe Zhao
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Analytic Formula ◽  
Analytic Approach ◽  
Work Space ◽  
Working Space ◽  
Computer Aided ◽  
Calculation Results ◽  
Position And Orientation ◽  
Orientation Workspace

An analytic approach and a simulation mechanism for solving position and the workspace of a 3-SPR parallel manipulator are proposed. First, a simulation mechanism of the 3-SPR parallel manipulator and a simulation mechanism of the 3-RPS parallel manipulator are created by using the computer aided geometry constraints and dimension-driving techniques. Second, some analytic formulas are derived for inverse and forward solving position and orientation of the 3-SPR parallel manipulator. Third, some available solutions from multi-solutions during deriving analytic formula are determined, and analytic inverse and forward solutions are verified by using simulation mechanisms. Finally, the workspace of the 3-SPR parallel manipulator is created and three key parameters for determining work space of two kinds of parallel manipulators are solved. Calculation results prove that the position working space of the 3-SPR parallel manipulator is much larger than that of the 3-RPS parallel manipulator, and the orientation workspace of the 3-SPR parallel manipulator is less than that of 3-RPS parallel manipulator.

Kinematics and Workspace Analyses of 3/3-RRRS Parallel Manipulator

2012 ◽  
Vol 155-156 ◽  
pp. 1090-1095 ◽  
Author(s):  
Meng Si Liu ◽  
Yi Cao ◽  
Qiu Ju Zhang ◽  
Clément Gosselin ◽  
Jian Chun Sun ◽  
...  
Keyword(s):  
Parallel Manipulator ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Geometrical Method ◽  
Three Dimensional Model ◽  
Forward Displacement ◽  
Theoretical Results ◽  
Orientation Workspace ◽  
Forward Displacement Analysis ◽  
Equivalent Mechanism

It is known that two primary disadvantages of parallel manipulators are the complicated forward kinematics and limited workspace. This paper mainly addressed the kinematics and workspace analyses of a 3/3-RRRS 6-DOF parallel manipulator. After a brief introduction of the 3/3 -RRRS 6-DOF parallel manipulator, a three-dimensional model and its relevant structure diagram are constituted, the forward and inverse displacement analyses of the 3/3-RRRS parallel manipulator are discussed in detail, especially, a novel geometrical method referred as equivalent mechanism is proposed for the forward displacement analysis of the manipulator under consideration. Based on the displacement analyses of the manipulator, a discretization method is proposed for the computation of the reachable position/orientation workspace of the 3/3-RRRS parallel manipulator, respectively. Examples of a 3/3-RRRS parallel manipulator are given to demonstrate these theoretical results.

Workspace and singularity analysis of a 3-DOF planar parallel manipulator with actuation redundancy

Robotica ◽  
2009 ◽  
Vol 27 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Jinsong Wang ◽  
Jun Wu ◽  
Tiemin Li ◽  
Xinjun Liu
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Actuation Redundancy ◽  
Hybrid Machine Tool ◽  
Planar Parallel Manipulator ◽  
Redundantly Actuated ◽  
Value Decomposition ◽  
The Relationship ◽  
Orientation Workspace

SUMMARYThis paper deals with the position workspace, orientation workspace, and singularity of a 3-degree-of-freedom (DOF) planar parallel manipulator with actuation redundancy, which is created by introducing a redundant link with active actuator to a 3-DOF nonredundant parallel manipulator. Based on the kinematic analysis, the position workspace and orientation workspace of the redundantly actuated parallel manipulator and its corresponding nonredundant parallel manipulator are analyzed, respectively. In the singularity analysis phase, the relationship between the generalized input velocity and the generalized output velocity is researched on the basis of the theory of singular value decomposition. Then a method to investigate the singularity of parallel manipulators is presented, which is used to determine the singularity of the redundantly actuated parallel manipulator. In contrast to the corresponding nonredundant parallel manipulator, the redundant one has larger orientation workspace and less singular configurations. The redundantly actuated parallel manipulator is incorporated into a 4-DOF hybrid machine tool which also includes a feed worktable to demonstrate its applicability.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

Structure Synthesis of 3-RRS Type Spatial Compliant Parallel Manipulator

2010 ◽  
Vol 44-47 ◽  
pp. 1375-1379
Author(s):  
Da Chang Zhu ◽  
Li Meng ◽  
Tao Jiang
Keyword(s):  
Parallel Manipulator ◽  
Compliant Mechanisms ◽  
Screw Theory ◽  
Weight Ratio ◽  
Parallel Manipulators ◽  
Robot System ◽  
New Approach ◽  
Structure Synthesis ◽  
Rigid Joints ◽  
Type 3

Parallel manipulators has been extensively studied by virtues or its high force-to-weight ratio and widely spread applications such as vehicle or flight simulator, a machine tool and the end effector of robot system. However, as each limb includes several rigid joints, assembling error is demanded strictly, especially in precision measurement and micro-electronics. On the other hand, compliant mechanisms take advantage of recoverable deformation to transfer or transform motion, force, or energy and the benefits of compliant mechanisms mainly come from the elimination of traditional rigid joints, but the traditional displacement method reduce the stiffness of spatial compliant parallel manipulators. In this paper, a new approach of structure synthesis of 3-DoF rotational compliant parallel manipulators is proposed. Based on screw theory, the structures of RRS type 3-DoF rotational spatial compliant parallel manipulator are developed. Experiments via ANSYS are conducted to give some validation of the theoretical analysis.

Effect of links deformation on motion precision of parallel manipulator based on flexible dynamics

2017 ◽  
Vol 44 (6) ◽  
pp. 776-787 ◽  
Author(s):  
Chunxia Zhu ◽  
Jay Katupitiya ◽  
Jing Wang
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Beam Theory ◽  
Parallel Manipulators ◽  
Dynamic Responses ◽  
Axial Deformation ◽  
Content Type ◽  
High Performing ◽  
Coupling Equations ◽  
The Relationship

Purpose Manipulator motion accuracy is a fundamental requirement for precision manufacturing equipment. Light weight manipulators in high speed motions are vulnerable to deformations. The purpose of this work is to analyze the effect of link deformation on the motion precision of parallel manipulators. Design/methodology/approach The flexible dynamics model of the links is first established by applying the Euler–Bernoulli beam theory and the assumed modal method. The rigid-flexible coupling equations of the parallel mechanism are further derived by using the Lagrange multiplier approach. The elastic energy resulting from spiral motion and link deformations are computed and analyzed. Motion errors of the 3-link torque-prismatic-torque parallel manipulator are then evaluated based on its inverse kinematics. The validation experiments are also conducted to verify the numerical results. Findings The lateral deformation and axial deformation are largest at the middle of the driven links. The axial deformation at the middle of the driven link is approximately one-tenth of the transversal deformation. However, the elastic potential energy of the transversal deformation is much smaller than the elastic force generated from axial deformation. Practical implications Knowledge on the relationship between link deformation and motion precision is useful in the design of parallel manipulators for high performing dynamic responses. Originality/value This work establishes the relationship between motion precision and the amount of link deformation in parallel manipulators.

scholarly journals Workspace Delineation of Cable-Actuated Parallel Manipulators

2004 ◽  
Author(s):  
Ethan Stump ◽  
Vijay Kumar
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Extensive Literature ◽  
Reachable Workspace ◽  
Planar Parallel Manipulator ◽  
Analytic Expressions

While there is extensive literature available on parallel manipulators in general, there has been much less attention given to cable-driven parallel manipulators. In this paper, we address the problem of analyzing the reachable workspace using the tools of semi-definite programming. We build on earlier work [1, 2] done using similar techniques by deriving limiting conditions that allow us to compute analytic expressions for the boundary of the reachable workspace. We illustrate this computation for a planar parallel manipulator with four actuators.

scholarly journals Regions of Feasible Point-to-Point Trajectories in the Cartesian Workspace of Fully-Parallel Manipulators

1999 ◽  
Author(s):  
Damien Chablat ◽  
Philippe Wenger
Keyword(s):  
Parallel Manipulator ◽  
Cartesian Product ◽  
Parallel Manipulators ◽  
Joint Space ◽  
Inverse Kinematic ◽  
Connected Components ◽  
Feasible Point ◽  
Cartesian Space ◽  
Point Trajectories ◽  
Point To Point

Abstract The goal of this paper is to define the n-connected regions in the Cartesian workspace of fully-parallel manipulators, i.e. the maximal regions where it is possible to execute point-to-point motions. The manipulators considered in this study may have multiple direct and inverse kinematic solutions. The N-connected regions are characterized by projection, onto the Cartesian workspace, of the connected components of the reachable configuration space defined in the Cartesian product of the Cartesian space by the joint space. Generalized octree models are used for the construction of all spaces. This study is illustrated with a simple planar fully-parallel manipulator.

Singularity robust inverse dynamics of planar 2-RPR parallel manipulators

2004 ◽  
Vol 218 (7) ◽  
pp. 721-730 ◽  
Author(s):  
S Kemal Ider
Keyword(s):  
Parallel Manipulator ◽  
Inverse Dynamics ◽  
Full Rank ◽  
Parallel Manipulators ◽  
Parallel Robots ◽  
Dynamic Equations ◽  
Revolute Joints ◽  
Planar Parallel Manipulator ◽  
Pass Through ◽  
Full Utilization

In planar parallel robots, limitations occur in the functional workspace because of interference of the legs with each other and because of drive singularities where the actuators lose control of the moving platform and the actuator forces grow without bounds. A 2-RPR (revolute, prismatic, revolute joints) planar parallel manipulator with two legs that minimizes the interference of the mechanical components is considered. Avoidance of the drive singularities is in general not desirable since it reduces the functional workspace. An inverse dynamics algorithm with singularity robustness is formulated allowing full utilization of the workspace. It is shown that if the trajectory is planned to satisfy certain conditions related to the consistency of the dynamic equations, the manipulator can pass through the drive singularities while the actuator forces remain stable. Furthermore, for finding the actuator forces in the vicinity of the singular positions a full rank modification of the dynamic equations is developed. A deployment motion is analysed to illustrate the proposed approach.

Sign in / Sign up

Export Citation Format

Share Document