Type synthesis of 4-DOF parallel kinematic mechanisms based on Grassmann line geometry and atlas method

2013 ◽  
Vol 26 (6) ◽  
pp. 1073-1081 ◽  
Author(s):  
Fugui Xie ◽  
Tiemin Li ◽  
Xinjun Liu
Keyword(s):  
Type Synthesis ◽  
Line Geometry ◽  
Grassmann Line Geometry ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Atlas Method ◽  
Kinematic Mechanisms

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.

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.

Multiobjective optimization of parallel kinematic mechanisms by the genetic algorithms

Robotica ◽  
2011 ◽  
Vol 30 (5) ◽  
pp. 783-797 ◽  
Author(s):  
Ridha Kelaiaia ◽  
Olivier Company ◽  
Abdelouahab Zaatri
Keyword(s):  
Genetic Algorithms ◽  
Multiobjective Optimization ◽  
High Speed ◽  
Optimization Problem ◽  
Multiobjective Optimization Problem ◽  
Dimensional Synthesis ◽  
Nsga Ii ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Kinematic Mechanisms

SUMMARYIt is well known that Parallel Kinematic Mechanisms (PKMs) have an intrinsic dynamic potential (very high speed and acceleration) with high precision and high stiffness. Nevertheless, the choice of optimal dimensions that provide the best performances remains a difficult task, since performances strongly depend on dimensions. On the other hand, there are many criteria of performance that must be taken into account for dimensional synthesis, and which are sometimes antagonist. This paper presents an approach of multiobjective optimization for PKMs that takes into account several criteria of performance simultaneously that have a direct impact on the dimensional synthesis of PKMs. We first present some criteria of performance such as the workspace, transmission speeds, stiffness, dexterity, precision, as well as dynamic dexterity. Secondly, we present the problem of dimensional synthesis, which will be defined as a multiobjective optimization problem. The method of genetic algorithms is used to solve this type of multiobjective optimization problem by means of NSGA-II and SPEA-II algorithms. Finally, based on a linear Delta architecture, we present an illustrative application of this methodology to a 3-axis machine tool in the context of manufacturing of automotive parts.

Study of Redundantly Actuated DELTA-Type Parallel Kinematic Mechanisms

2017 ◽  
pp. 291-298 ◽  
Author(s):  
Burkhard Corves ◽  
Seyed Amirreza Shahidi ◽  
Michael Lorenz ◽  
Sami Charaf Eddine ◽  
Mathias Hüsing
Keyword(s):  
Delta Type ◽  
Redundantly Actuated ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Kinematic Mechanisms

Comparative Analysis of a Redundant Pentapod Parallel Kinematic Machine

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Arta Alagheband ◽  
Masih Mahmoodi ◽  
James K. Mills ◽  
Beno Benhabib
Keyword(s):  
Comparative Analysis ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Parallel Kinematic Machine ◽  
High Stiffness ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Stiffness Characteristics ◽  
Kinematic Mechanisms ◽  
Platform Tilt

Parallel kinematic mechanisms (PKMs) provide high stiffness and compact structures that are suitable for a large number of applications, including 5-axis milling. This paper presents a new pentapod-based PKM with an additional redundant degree-of-freedom (DOF) capable of reaching platform tilt angles of at least 90 deg over a large workspace. The proposed new PKM has a 6DOF 4 × SPRR + 1 × PSPR architecture. It is compared herein to Metrom® Pentapod as well as to several other pertinent PKMs in terms of workspace and dynamic stiffness. It is shown that the proposed mechanism can yield a tangibly larger workspace volume, when compared to those PKMs, while maintaining its high stiffness characteristics.

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