Mobility and Workspace of a 3-5R Translational Parallel Mechanism

2006 ◽  
Author(s):  
Syamsul Huda ◽  
Yukio Takeda
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Translational Motion ◽  
Numerical Calculations ◽  
Mobility Analysis ◽  
Spatial Mechanism ◽  
Size And Shape

A study about mobility and workspace of a 3-5R translational parallel spatial mechanism that has three symmetric limbs is presented. Mobility analysis based on the screw theory and numerical calculations were carried out to show if the proposed mechanism enabled the pure translational motion of a platform. The size and shape of workspace of the mechanism were also evaluated.

Kinematic Analyses of 5-DOF 3-RCRR Parallel Mechanism

2005 ◽  
Author(s):  
Zhen Huang ◽  
Si J. Zhu
Keyword(s):  
Reference Point ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Mobility Analysis ◽  
End Effector ◽  
Numerical Example ◽  
Rotation Center ◽  
Kinematic Analyses ◽  
Base Platform ◽  
Virtual Pairs

This paper presents the kinematic analyses of a 5-DOF 3-RCRR parallel mechanism. The end-effector of this mechanism can rotate round rotation center and one reference point on it can translate in a plane parallels to the base platform. Since the traditional Kutzbach-Gru¨bler formula is not valid for this mechanism, the modified Kutzbach-Gru¨bler formula and screw theory are used in the mobility analysis. The Duffy’s spherical analytic theory is used in forward/reverse position analyses. In forward/reverse velocity/acceleration analyses, virtual mechanism principle is used to build a virtual parallel mechanism (3-PvRCRR), which is equivalent to the initial mechanism (3-RCRR) on kinematics if all rates of virtual pairs (Pv) are set to be zero. At the end, some kinematics curves are presented with a numerical example.

New Procedure for Constraint Determination in Mobility Analysis for Classical Coupled Linkages

2013 ◽  
Vol 281 ◽  
pp. 230-233
Author(s):  
Jing Fang Liu ◽  
Xiao Ou Huang ◽  
Yue Qing Yu ◽  
Zhen Huang
Keyword(s):  
Traditional Method ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Mobility Analysis ◽  
Classical Mechanism

A coupled mechanism is different from common parallel mechanism with independent limbs, so it is impossible to analyze the constraint and mobility by the traditional method based on screw theory. To overcome this problem, this paper proposes a new procedure to determine the overconstraint for coupled mechanisms based on screw theory, where a coupled mechanism is decomposed into several basic elements. The validity of the new procedure is further proved from the constraint and mobility analysis for a classical mechanism.

Mobility Analysis of a Novel 3-5R Parallel Mechanism Family

2004 ◽  
Vol 126 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Q. C. Li ◽  
Z. Huang
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Kinematic Chain ◽  
Parallel Mechanisms ◽  
Mobility Analysis

Mobility analysis of a novel 3-5R parallel mechanism family whose limb consists of a 2R and a 3R parallel subchain is performed by the aid of screw theory. A mobility criterion applicable to such 3-leg parallel mechanisms in which each kinematic chain contains five kinematic pairs is proposed. It is shown that under different structural conditions, the 3-5R parallel mechanism can have 3, 4, or 5 DOF (degrees of freedom). The structural conditions that guarantee the full-cycle mobility are analyzed. The analysis and the method presented in this paper will be helpful in using such a 3-5R parallel mechanism family and introduce new insights into the mobility analysis of parallel mechanisms.

Mobility Analysis of the 3-UPU Parallel Mechanism Assembled for a Pure Translational Motion

2002 ◽  
Vol 124 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Raffaele Di Gregorio ◽  
Vincenzo Parenti-Castelli
Keyword(s):  
Path Planning ◽  
Parallel Mechanism ◽  
Translational Motion ◽  
Analytic Form ◽  
Geometric Interpretation ◽  
Parallel Mechanisms ◽  
Basic Information ◽  
Mobility Analysis ◽  
Singular Configurations ◽  
Translation Motion

The occurrence of singular configurations in parallel mechanisms must be avoided during motion since the actuators cannot control motion even in the neighborhood of these configurations. As a consequence, the knowledge of the singular configurations of the mechanism is important for control purposes, for singularity-free path planning, and also represents basic information for the synthesis of a desired mechanism workspace free from singularities. In this paper the mobility analysis of the 3-UPU parallel mechanism assembled for obtaining a pure translation motion of the output platform is performed and both translation and rotation singularity loci are presented in analytic form and their geometric interpretation is given.

Configuration and actuation analysis of a 2US+UPS asymmetrical parallel mechanism

2012 ◽  
Vol 226 (9) ◽  
pp. 2296-2308 ◽  
Author(s):  
Yun Qin ◽  
Jian S Dai
Keyword(s):  
Numerical Analysis ◽  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Singularity Analysis ◽  
Mobility Analysis ◽  
Dimensional Representation ◽  
Actuation Scheme

This article investigates an asymmetrical parallel mechanism with one universal–prismatic–spherical limb and two universal–spherical limbs and focuses on its mobility, configuration and dexterity analysis. The mobility analysis via screw theory reveals the mechanism of mobility four and leads to kinematic analysis. Mechanism configuration is then revealed with its model and actuation scheme. This leads to the singularity analysis and in particular to a new expression of direct kinematic near-singularity in an extended four-dimensional representation. Numerical analysis of local dexterity, which is illustrated with the change of platform position parameters, presents the range of better dexterous space.

Actuating Input Selection of 5-UPS/PRPU Parallel Machine Tool

2005 ◽  
Author(s):  
Jian-She Gao ◽  
Ren-Cheng Zheng ◽  
Yong-Sheng Zhao
Keyword(s):  
Parallel Mechanism ◽  
Basic Problem ◽  
Screw Theory ◽  
Parallel Machine ◽  
Condition Numbers ◽  
Constraint Matrix ◽  
Input Selection ◽  
Moving Platform ◽  
Parallel Machine Tool ◽  
Selection Of

The actuating input selection is an important basic problem for the parallel mechanism. Based on the screw theory, the constraint screw can be got after locking a kinematic pair in any limb, which can be taken as actuating wrench acted on the moving platform of the parallel mechanism. The constraint screw matrix is composed of the structure constraint screws and the constraint screws of the actuating pairs. The reasonableness of input selection can be judged by the rank of the constraint matrix. The performance of the combinations of actuating inputs is evaluated by the condition numbers of the force constraint matrix and the torque constraint matrix respectively. The theory presented is validated by the simulation and the maching test.

A Systematical Approach for Structure Synthesis of Parallel Mechanisms Based on Single-Open-Chain Modules and Its Application

2009 ◽  
Author(s):  
Ting-Li Yang ◽  
An-Xin Liu ◽  
Qiong Jin ◽  
Yu-Feng Luo ◽  
Lu-Bin Hang ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Systematic Approach ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Open Chain ◽  
Structure Synthesis ◽  
Vector Algebra ◽  
Algebra Theory ◽  
Position And Orientation

Based on previous research results presented by authors, this paper proposes a novel systematic approach for structure synthesis of all parallel mechanisms (excluding Bennett mechanism etc), which is totally different from the approaches based on screw theory and based on displacement subgroup. Main characteristics of this approach are: (a) the synthesized mechanisms are non-instantaneous ones, and (b) only simple mathematical tools (vector algebra, theory of sets, etc.) are used. Main steps of this approach include: (1) Determining functional and structural requirements of the parallel mechanism to be synthesized, such as position and orientation characteristic (POC) matrix, degree of freedom (DOF), etc. (2) Type synthesis of branches. (3) Assembling of branches (determining the geometry constraint conditions among the branches attached between the moving platform and the frame, and checking the DOF). (4) Identifying the inactive joints. (5) Selecting the actuating joints. In order to illustrate the whole procedure, the type synthesis of spherical parallel mechanisms is studied using this approach.

Dimensional Synthesis of a Novel 2T2R Parallel Manipulator for Medical Applications

2014 ◽  
Author(s):  
Nitish Kumar ◽  
Olivier Piccin ◽  
Bernard Bayle
Keyword(s):  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Screw Theory ◽  
Structural Parameters ◽  
Geometric Analysis ◽  
Medical Applications ◽  
Dimensional Synthesis ◽  
Synthesis Algorithm ◽  
Percutaneous Procedures ◽  
Actuated Joints

This paper deals with the dimensional synthesis of a novel parallel manipulator for medical applications. This parallel mechanism has a novel 2T2R mobility derived from the targeted application of needle manipulation. The kinematic design of this 2T2R manipulator and its novelty are illustrated in relation to the percutaneous procedures. Due to the demanding constraints on its size and compactness, achieving a large workspace especially in orientation, is a rather difficult task. The workspace size and kinematic constraint analysis are considered for the dimensional synthesis of this 2T2R parallel mechanism. A dimensional synthesis algorithm based on the screw theory and the geometric analysis of the singularities is described. This algorithm also helps to eliminate the existence of voids inside the workspace. The selection of the actuated joints is validated. Finally, the dimensions of the structural parameters of the mechanism are calculated for achieving the required workspace within the design constraints of size, compactness and a preliminary prototype without actuators is presented.

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