scholarly journals Type Synthesis and Typical Application of 1T2R-Type Parallel Robotic Mechanisms

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Tiemin Li
Keyword(s):  
Synthesis Method ◽  
Type Synthesis ◽  
Line Geometry ◽  
Typical Application ◽  
Hybrid Mechanism ◽  
Grassmann Line Geometry ◽  
Lower Mobility ◽  
Atlas Method ◽  
Mutual Conversion ◽  
Five Axis

This paper focuses on the 1T2R-type (T: translational DOF; R: rotational DOF) parallel robotic mechanisms (PKMs) and discusses their type synthesis and typical application in five-axis machine tools. Based on Grassmann line geometry and atlas method, a systematic method dealing with the type synthesis of lower mobility PKMs is introduced. The Blanding rules and generalized Blanding rules, which are the criterions in realizing the mutual conversion between the freedom-space atlas and the constraint-space atlas, are summarized and discussed in detail. Thereafter, the entire procedure of the type synthesis is presented, and the type synthesis of 1T2R PKMs is carried out. Based on the synthesis results, a five-axis hybrid mechanism is proposed and a machine tool is developed consequently. The type synthesis method presented in this paper is intuitive and concise and can be used in the type synthesis of other lower mobility PKMs.

Design of a novel 3-DoF parallel kinematic mechanism: type synthesis and kinematic optimization

Robotica ◽  
2014 ◽  
Vol 33 (3) ◽  
pp. 622-637 ◽  
Author(s):  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Chao Wang
Keyword(s):  
Line Graph ◽  
Synthesis Method ◽  
Type Synthesis ◽  
Parallel Kinematic Mechanism ◽  
Grassmann Line Geometry ◽  
Parallel Kinematic ◽  
Three Degree Of Freedom ◽  
Five Axis ◽  
Kinematic Optimization ◽  
Kinematic Mechanism

SUMMARYThis paper deals with the design of a three-degree-of-freedom (3-DoF) parallel kinematic mechanism (PKM) with high orientational capability. First, a type synthesis method based on Grassmann line geometry and a line-graph method is proposed, and a novel 3-DoF PKM is derived based on this method. Thereafter, the parasitic motions of the derived mechanism are identified under two different orientation description methods, i.e., Tilt-and-Torsion angles (T&T angles) and Roll-Pitch-Yaw angles (RPY angles), and the kinematic optimization considering the motion/force transmissibility is carried out. On this basis, the orientational capability of the discussed mechanism is investigated, and the high orientational capability is demonstrated. The design of the 3-DoF PKM in this paper is very meaningful to the development of the five-axis machine tools with hybrid architectures. The design methods of type synthesis and kinematic optimization can also be used in the design of other PKMs.

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

Singularity Analysis of 5-RPRRR Parallel Mechanisms via Grassmann Line Geometry

2009 ◽  
Author(s):  
Mehdi Tale Masouleh ◽  
Cle´ment Gosselin
Keyword(s):  
Jacobian Matrix ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
General Mechanism ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Line Geometry ◽  
Singular Configurations ◽  
Highly Nonlinear ◽  
Grassmann Line Geometry

This paper investigates the singular configurations of five-degree-of-freedom parallel mechanisms generating the 3T2R motion and comprising five identical legs of the RPUR type. The general mechanism was recently revealed by performing the type synthesis for symmetrical 5-DOF parallel mechanisms. In this study, some simplified designs are proposed for which the singular configurations can be predicted by means of the so-called Grassmann line geometry. This technique can be regarded as a powerful tool for analyzing the degeneration of the Plu¨cker screw set. The main focus of this contribution is to predict the actuation singularity, for a general and simplified design, without expanding the determinant of the inverse Jacobian matrix (actuated constraints system) which is highly nonlinear and difficult to analyze.

Type Synthesis of a 1T Symmetric Coupling Mechanism with the Method of Separation and Merger

2014 ◽  
Vol 635-637 ◽  
pp. 1290-1293
Author(s):  
Shou Li Zhang ◽  
Jing Fang Liu ◽  
Yue Qing Yu
Keyword(s):  
Linear Combination ◽  
Parallel Mechanism ◽  
Creative Design ◽  
Coupling Mechanism ◽  
Type Synthesis ◽  
Structural Synthesis ◽  
Hybrid Mechanism ◽  
Coupled Structures ◽  
Coupling Mechanisms

The structural synthesis is the primary and the most important issue in the process of mechanism creative design. In the paper, Firstly, select a 1T symmetric parallel mechanism, and the constraint and mobility of the branches can be analyzed. With the method of linear combination of the screws, the new branches are constructed. Then, using the measure of separation and merger, parts of the limbs of the parallel mechanism can be replaced by equivalent coupled structures, so corresponding symmetric coupling mechanisms with equal mobility are synthesized. Finally, solving the constraint screws of the branch of the coupling mechanism, in order to prove the hybrid mechanism is full-cycle or not.

Method for the Creation of a Six Bar Linkage to Simultaneously Carry Two Rigid Bodies Through Four Coordinated Positions

2012 ◽  
Author(s):  
Ronald A. Zimmerman
Keyword(s):  
Synthesis Method ◽  
Rigid Bodies ◽  
Type Synthesis ◽  
Linkage Mechanism ◽  
Center Point ◽  
Seat Cushion ◽  
The Creation ◽  
Linkage Synthesis

A method for the creation of a six bar linkage with two ground pivots to simultaneously carry two rigid bodies through four coordinated positions was invented and is described and illustrated herein. Type synthesis was used to identify possible linkage classes and specific types of possible six bar linkages. A linkage synthesis method which superimposes three Burmester center point curves to create a six bar linkage mechanism with two ground pivots, to carry two coupled rigid bodies simultaneously through four specified, coordinated positions was developed and is demonstrated. An extension of the method to carry two non-coupled rigid bodies through four positions is indicated. This method was invented in the process of developing a 2nd row automotive truck seat, which is used as an example to illustrate the procedure. A six bar linkage which carries an automotive truck seat back and seat cushion through four coordinated positions is shown.

Type Synthesis of 3-DOF Translational Parallel Manipulators Based on Atlas of DOF Characteristic Matrix

2006 ◽  
Author(s):  
Jingjun Yu ◽  
Jian S. Dai ◽  
Xin-Jun Liu ◽  
Shusheng Bi ◽  
Guanghua Zong
Keyword(s):  
System Theory ◽  
Lie Group ◽  
Synthesis Method ◽  
Parallel Manipulators ◽  
Complete Classification ◽  
Characteristic Matrix ◽  
Type Synthesis ◽  
Lie Group Theory ◽  
Low Degree ◽  
New Type

Low-degree-of-freedom (Low-DOF) parallel manipulators (PMs) have drawn extensive interest, particularly in type synthesis in which two main approaches were established in the reciprocal screw system theory and Lie group theory. This paper aims at proposing a new type synthesis method to complementing the above methods. For this purpose, the concept of the DOF characteristic matrix, originated from displacement subgroup and displacement submanifold, is proposed. A new but general approach based on the atlas of DOF Characteristic Matrix is addressed for both exhaustive classification and type synthesis of low-DOF PMs. Compared to the method based on Lie group, the proposed approach is prone to construct an orthogonal structure and easy to realize the complete classification and exhaustive enumeration of a class of low-DOF PM. In order to verify the effectiveness of the proposed method, type synthesis of Translational PMs (TPMs) particularly in ones with an orthogonal structure is performed, resulting in some novel orthogonal TPMs.

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