Performance Indices for Parallel Robots Considering Motion/Force Transmissibility

2014 ◽  
pp. 35-43 ◽  
Author(s):  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Jie Li
Keyword(s):  
Parallel Robots ◽  
Performance Indices ◽  
Force Transmissibility

Screw Theory-Based Motion/Force Transmissibility Analysis of High-Speed Parallel Robots With Articulated Platforms

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Qizhi Meng ◽  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Yukio Takeda
Keyword(s):  
High Speed ◽  
Screw Theory ◽  
Parallel Robots ◽  
Essential Property ◽  
Performance Indices ◽  
Transmission Index ◽  
Force Transmissibility ◽  
Kinematic Performance ◽  
Insight Into ◽  
Local Transmission

Abstract Motion/force transmissibility is an essential property reflecting the kinematic performance of parallel robots. Research on this performance of the single-platform parallel robots (SPPRs) has long been concerned and studied. In contrast, although many innovations and applications of the high-speed articulated-platform parallel robots (APPRs) have been presented, few studies on their motion/force transmissibility have been reported. This paper deals with the motion/force transmissibility analysis of high-speed parallel robots with articulated platforms. A modified output transmission index (MOTI) for the high-speed parallel robots with articulated platforms is proposed based on a newly defined concept of equivalent transmission wrench screw. Furthermore, by having an insight into the instantaneous relative motion inside the mobile platform, a medial transmission index (MTI) is proposed to evaluate its internal motion/force transmissibility. Based on these foundations, the local transmission index (LTI) is redefined as the minimum value of the input, modified output, and medial transmission indices. Under the framework of the above performance indices, motion/force transmissibility analysis of two typical high-speed articulated-platform parallel robots, i.e., Heli4 and Par4, are presented. The proposed indices are excepted to be applied to the optimal design of high-speed parallel robots with articulated platforms.

Design and Motion/Force Transmissibility Analysis of Two Motion-Decoupled 3T1R Parallel Robots with Full Rotational Capability

2021 ◽  
pp. 460-469
Author(s):  
Xin Yuan ◽  
Qizhi Meng ◽  
Fugui Xie ◽  
Zhenguo Nie ◽  
Xin-Jun Liu
Keyword(s):  
Parallel Robots ◽  
Force Transmissibility

scholarly journals Screw Theory Based Singularity Analysis of Lower-Mobility Parallel Robots considering the Motion/Force Transmissibility and Constrainability

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Xiang Chen ◽  
Xin-Jun Liu ◽  
Fugui Xie
Keyword(s):  
Screw Theory ◽  
Mathematical Problem ◽  
Engineering Application ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
Input And Output ◽  
Lower Mobility ◽  
Force Transmissibility ◽  
Output Constraint

Singularity is an inherent characteristic of parallel robots and is also a typical mathematical problem in engineering application. In general, to identify singularity configuration, the singular solution in mathematics should be derived. This work introduces an alternative approach to the singularity identification of lower-mobility parallel robots considering the motion/force transmissibility and constrainability. The theory of screws is used as the mathematic tool to define the transmission and constraint indices of parallel robots. The singularity is hereby classified into four types concerning both input and output members of a parallel robot, that is, input transmission singularity, output transmission singularity, input constraint singularity, and output constraint singularity. Furthermore, we take several typical parallel robots as examples to illustrate the process of singularity analysis. Particularly, the input and output constraint singularities which are firstly proposed in this work are depicted in detail. The results demonstrate that the method can not only identify all possible singular configurations, but also explain their physical meanings. Therefore, the proposed approach is proved to be comprehensible and effective in solving singularity problems in parallel mechanisms.

A New Approach for Singularity Analysis and Closeness Measurement to Singularities of Parallel Manipulators

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Xin-Jun Liu ◽  
Chao Wu ◽  
Jinsong Wang
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Challenging Problem ◽  
Performance Indices ◽  
New Approach ◽  
Singular Configurations ◽  
Different Types ◽  
Force Transmissibility ◽  
Singular Configuration

Singularity analysis is one of the most important issues in the field of parallel manipulators. An approach for singularity analysis should be able to not only identify all possible singularities but also explain their physical meanings. Since a parallel manipulator is always out of control at a singularity and its neighborhood, it should work far from singular configurations. However, how to measure the closeness between a pose and a singular configuration is still a challenging problem. This paper presents a new approach for singularity analysis of parallel manipulators by taking into account motion/force transmissibility. Several performance indices are introduced to measure the closeness to singularities. By using these indices, a uniform “metric” can be found to represent the closeness to singularities for different types of nonredundant parallel manipulators.

Motion/Force Transmissibility Based Performance Evaluation of a 6-DOF Parallel Robot With 2-DOF Active Joints

2018 ◽  
Author(s):  
Bin Mei ◽  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Xuan Luo
Keyword(s):  
Performance Evaluation ◽  
Degrees Of Freedom ◽  
Evaluation Method ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Six Degrees Of Freedom ◽  
Transmission Index ◽  
Force Transmissibility ◽  
Local Transmission ◽  
Active Joints

3-PP(Pa)S robot is a six degrees of freedom (DOFs) parallel mechanism with 2-DOF active planar joint. For the design and application of the 3-PP(Pa)S robot, it is essential to investigate the motion/force transmissibility of the robot. But previous studies of the motion/force transmissibility have mainly focused on the parallel robots with 1-DOF active joints and thus cannot be directly applied to the 3-PP(Pa)S robot. In this paper, input twist subspace, transmission wrench subspace and output twist subspace are investigated to build mathematical models of the twists and wrenches corresponding to the 2-DOF active planar joint. Afterwards, based on the previous established frame of the local transmission index, some extended performance evaluation indices are defined to describe the motion/force transmissibility of the 3-PP(Pa)S robot. On this basis, the singularity and motion/force transmissibility of this mechanism are investigated. The motion/force transmissibility evaluation method is meaningful and applicable for the 3-PP(Pa)S parallel robot with 2-DOF active joints and can be further applied to other mechanisms with multi-DOF active joints.

Determination of the Workspace of Parallel Manipulators Using a CAD Software and the Concept of Virtual Chains

2013 ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
Performance Indices ◽  
Workspace Analysis ◽  
Static Calculation

Development of a new parallel manipulator can be very time consuming due to the traditional method of producing kinematic, dynamic and static calculation models and then evaluating them to determine aspects of the manipulator’s performance indices such as the mechanism’s workspace and singularity analysis. By extending the virtual chain approach to the type synthesis of parallel manipulators, this paper proposes a virtual-chain approach to the workspace analysis of parallel manipulators. This method is illustrated by producing and evaluating the workspace of several parallel robots including the well known DELTA robot by utilising the three-dimensional CAD software SolidWorks to produce a virtual prototype of a manipulator with an embedded virtual chain. The virtual chain represents the motion pattern of a manipulator’s end-effector and is very useful in the production of a graphical representation of the workspace of the manipulator. Using this approach, the link interferences and transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

Optimizing Stiffness and Dexterity of Planar Adaptive Cable-Driven Parallel Robots

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Saeed Abdolshah ◽  
Damiano Zanotto ◽  
Giulio Rosati ◽  
Sunil K. Agrawal
Keyword(s):  
Trajectory Planning ◽  
Performance Index ◽  
Elastic Stiffness ◽  
Parallel Robots ◽  
Kinematic Redundancy ◽  
Performance Indices ◽  
Systematic Method ◽  
End Effector ◽  
Driven Systems ◽  
Optimal Values

Adaptive cable-driven parallel robots are a special subclass of cable-driven systems in which the locations of the pulley blocks are modified as a function of the end-effector pose to obtain optimal values of given performance indices within a target workspace. Due to their augmented kinematic redundancy, such systems enable larger workspace volume and higher performance compared to traditional designs featuring the same number of cables. Previous studies have introduced a systematic method to optimize design and trajectory planning of the moving pulley-blocks for a given performance index. In this paper, we study the motions of the pulley blocks that optimize two performance indices simultaneously: stiffness and dexterity. Specifically, we present a method to determine the pulley blocks motions that guarantee ideal dexterity with the best feasible elastic stiffness, as well as those that guarantee isotropic elastic stiffness with the best feasible dexterity. We demonstrate the proposed approach on some practical cases of planar adaptive cable-driven parallel robots.

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