Analytic singularity equation and analysis of six-DOF parallel manipulators using local structurization method

1999 ◽  
Vol 15 (4) ◽  
pp. 612-622 ◽  
Author(s):  
Doik Kim ◽  
Wankyun Chung
Keyword(s):  
Parallel Manipulators ◽  
Analytic Singularity ◽  
Six Dof

Forward Kinematics Solution Distribution and Analytic Singularity-Free Workspace of Linear-Actuated Symmetrical Spherical Parallel Manipulators

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Dongming Gan ◽  
Jian S. Dai ◽  
Jorge Dias ◽  
Lakmal Seneviratne
Keyword(s):  
Coordinate System ◽  
Optimization Design ◽  
Parallel Manipulators ◽  
Geometric Constraints ◽  
Forward Kinematics ◽  
Kinematics Model ◽  
Analytic Singularity ◽  
Dynamics And Control ◽  
Rotation Motion ◽  
Forward Kinematic

This paper presents a new kinematics model for linear-actuated symmetrical spherical parallel manipulators (LASSPMs) which are commonly used considering their symmetrical kinematics and dynamics properties. The model has significant advantages in solving the forward kinematic equations, and in analytically obtaining singularity loci and the singularity-free workspace. The Cayley formula, including the three Rodriguez–Hamilton parameters from a general rotation matrix, is provided and used in describing the rotation motion and geometric constraints of LASSPMs. Analytical solutions of the forward kinematic equations are obtained. Then singularity loci are derived, and represented in a new coordinate system with the three Rodriguez–Hamilton parameters assigned in three perpendicular directions. Limb-actuation singularity loci are illustrated and forward kinematics (FK) solution distribution in the singularity-free zones is discussed. Based on this analysis, unique forward kinematic solutions of LASSPMs can be determined. By using Cayley formula, analytical workspace boundaries are expressed, based on a given mechanism structure and input actuation limits. The singularity-free workspace is demonstrated in the proposed coordinate system. The work gives a systematic method in modeling kinematics, singularity and workspace analysis which provides new optimization design index and a simpler kinematics model for dynamics and control of LASSPMs.

A Class of Parallel Manipulators Based on Kinematically Simple Branches

1994 ◽  
Vol 116 (3) ◽  
pp. 908-914 ◽  
Author(s):  
R. P. Podhorodeski ◽  
K. H. Pittens
Keyword(s):  
Parallel Manipulators ◽  
Parallel Structure ◽  
End Effector ◽  
Forward Displacement ◽  
Parallel Class ◽  
Serial Chain ◽  
Order Polynomial ◽  
Six Dof ◽  
Actuated Joints ◽  
Chain Branch

Parallel manipulators consisting of serial branches acting in parallel on a common end effector are examined. All nonredundant, six DOF manipulators corresponding to this in-parallel class of structures are enumerated. A specific in-parallel structure, three branches with two actuated joints per branch (3–2,2,2), is chosen as most promising based upon performance considerations. A class of kimematically simple (KS) serial-chain branch joint layouts suitable for the chosen in-parallel structure is defined. Arguments based upon kinematic equivalency of the branches and mobility of the assembled in-parallel manipulator chain are used to show that there exist only five unique branch joint-layouts belonging to the KS class. It is demonstrated that the solution to the inverse displacement problem for in-parallel manipulators based on the KS branches can be expressed in a closed form. Furthermore, the 3–2,2,2 in-parallel manipulators are shown to belong to a family of manipulators whose forward displacement solutions can be resolved through roots of a 16th order polynomial.

New Indices for Optimal Design of Redundantly Actuated Parallel Manipulators

2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Qinchuan Li ◽  
Ningbin Zhang ◽  
Feibo Wang
Keyword(s):  
Optimal Design ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Mean Value ◽  
Transmission Performance ◽  
Transmission Index ◽  
Redundantly Actuated ◽  
Lower Mobility ◽  
Six Dof ◽  
Force Transmissibility

Redundantly actuated parallel manipulators (PMs) receive growing interest due to their reduced singularity and enlarged workspace. This paper proposes new indices for optimal design and analysis of redundantly actuated PMs by evaluating their motion/force transmissibility. First, we proposed a method to extract a multi-DOF (degrees-of-freedom) redundantly actuated PM into several subsidiary one-DOF PMs with two or more actuators by locking some actuators in an ergodic manner. Then, a new index of output transmission performance is proposed by investigating the mean value of the instantaneous power produced by the multiple actuation wrenches and one twist of the moving platform of one-DOF PMs. A local transmission index (LTI) is defined as the minimum value of the index of output and input transmission performance. A global transmission index (GTI) is then established based on the LTI. The proposed LTI and GTI are coordinate-free and have clear physical interpretation. Finally, the validity and universality of the new indices are demonstrated by optimization and analysis of redundantly actuated lower-mobility PMs with extra articulated six-DOF or limited-DOF limbs.

Size optimization of the moving platform for cable-driven parallel manipulators based on stiffness characteristics

2017 ◽  
Vol 232 (11) ◽  
pp. 2057-2066 ◽  
Author(s):  
Bin Zhang ◽  
Wei-Wei Shang ◽  
Shuang Cong ◽  
Yi Liu
Keyword(s):  
Parallel Manipulators ◽  
Descent Method ◽  
Static Stiffness ◽  
Simulation Experiments ◽  
Six Dof ◽  
Different Shapes ◽  
Moving Platform ◽  
Stiffness Characteristics ◽  
The Stability ◽  
The Relationship

To improve the mechanical structure of cable-driven parallel manipulators (CDPMs), the size of the moving platform is optimized based on the stiffness characteristics. First, the relationship between the stability and the static stiffness of CDPMs is analyzed, and a way of judging whether CDPMs are stable at a given pose is proposed. Therefore, the space formed by all stable poses is defined as the stable workspace. Second, the effects of two different shapes of the moving platform in different sizes on the stable workspace are investigated numerically. Furthermore, by maximizing the stable workspace, the size of the moving platform is optimized using the grouped coordinate descent method. Finally, the simulation experiments are implemented on a six-DOF spatial CDPM with eight cables. The simulation results indicate that the shape and size of the moving platform both have effects on the stable workspace, and the volume of the stable workspace can be enlarged by optimizing the size of the moving platform in the two different shapes.

Type Synthesis of Six-DOF Wrist-Partitioned Parallel Manipulators

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Xianwen Kong ◽  
Clément M. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
General Structure ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Type Synthesis ◽  
Forward Displacement ◽  
Serial Manipulators ◽  
Six Dof ◽  
Moving Platform ◽  
Actuated Joints

A six-DOF wrist-partitioned parallel manipulator is a parallel manipulator in which three of the six actuated joints are used to control the position of a point on the moving platform while the other three are further used to control the orientation of the moving platform. Such parallel manipulators are, in fact, the parallel counterparts of the wrist-partitioned serial manipulators, which are widely used in industry. Unlike parallel manipulators of a general structure, a six-DOF wrist-partitioned parallel manipulator usually has simple kinematic characteristics such as its forward displacement analysis and singularity analysis are easy to solve. This paper deals with the type synthesis of six-DOF wrist-partitioned parallel manipulators. An approach is first proposed for the type synthesis of this class of parallel manipulators. Using the proposed approach, six-DOF wrist-partitioned parallel manipulators can be constructed from the types of three-DOF nonoverconstrained spherical parallel manipulators. A large number of six-DOF wrist-partitioned parallel manipulators are then obtained, and several types of practical relevance are also identified.

Type Synthesis of Six-DOF Wrist-Partitioned Fully Parallel Manipulators

2007 ◽  
Author(s):  
Xianwen Kong ◽  
Cle´ment M. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
General Structure ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Type Synthesis ◽  
Forward Displacement ◽  
Serial Manipulators ◽  
Six Dof ◽  
Moving Platform ◽  
Actuated Joints

A six-DOF wrist-partitioned fully parallel manipulator is a parallel manipulator in which three of the six actuated joints are used to control the position of a point on the moving platform while the other three are further used to control the orientation of the moving platform. Such parallel manipulators are in fact the parallel counterparts of the wrist-partitioned serial manipulators, which are widely used in industry. Unlike parallel manipulators of a general structure, a six-DOF wrist-partitioned fully parallel manipulator usually has simple kinematic characteristics such as its forward displacement analysis and singularity analysis are easy to solve. This paper deals with the type synthesis of six-DOF wrist-partitioned fully parallel manipulators. An approach is first proposed for the type synthesis of this class of parallel manipulators. Using the proposed approach, six-DOF wrist-partitioned fully parallel manipulators can be constructed from the types of three-DOF non-overconstrained spherical parallel manipulators. A large number of six-DOF wrist-partitioned fully parallel manipulators are then obtained, and several types of practical relevance are also identified.

scholarly journals A Dexterity Comparison for 6 DOF Hybrid Robots

2020 ◽  
Author(s):  
MohammadAli Mohammadkhani ◽  
Ahmad Reza Haghighi
Keyword(s):  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Hybrid Mechanisms ◽  
Six Dof ◽  
Position And Orientation

Abstract In this paper, new hybrid robots are suggested which divided the task into a position and orientation tasks. The position mechanism controls the position whereas the orientation one manipulates the orientation of the end effector. These robots consist of a translational parallel manipulator and a rotational serial or parallel mechanism. The 3UPU or Tricept parallel manipulator and a three-axis gimbaled system or parallel shoulder manipulator are chosen for translational and rotational movements, respectively. The main goal of this paper is analyzing the development and combination of serial and parallel manipulators in order to increase their features. According to this purpose, serial and parallel mechanisms with three DOF are combined in a way to encompass six DOF space. It is shown hybrid mechanisms with less coupling between their subsystems are capable of increasing robot characteristics.

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