Workspace formulation of planar wire-actuated parallel manipulators

Robotica ◽  
2010 ◽  
Vol 29 (4) ◽  
pp. 607-617 ◽  
Author(s):  
Derek McColl ◽  
Leila Notash
Keyword(s):  
External Force ◽  
Parallel Manipulators ◽  
Applied Force ◽  
Mobile Platform ◽  
Static Force ◽  
Force Analysis ◽  
Wide Range

SUMMARYIn this paper, a generalized form of the antipodal method from multi-finger grasping is presented and implemented for investigating the workspace of a wide range of planar wire-actuated parallel manipulators. Manipulators with distinct wire attachment points on the base and mobile platform are considered, in the absence and presence of external force. The examined workspaces are verified with the corresponding workspaces developed using static force analysis. By applying an external force, modeled as a wire for the antipodal method, the characteristics of the manipulator could be altered by enlarging its workspace in the direction of the applied force.

Workspace Investigation of Wire-Actuated Parallel Manipulators With Uncertainties in Wire Connections

2010 ◽  
Author(s):  
Leila Notash ◽  
Derek McColl
Keyword(s):  
Parallel Manipulators ◽  
Mobile Platform ◽  
Static Force ◽  
Force Moment ◽  
Geometric Representations ◽  
The Wire

In this article, the effect of uncertainties in wire connections on the workspace generation of wire-actuated parallel manipulators is investigated. The geometric representations of uncertainties in the attachments points of wires to the base and to the mobile platform are developed. Two methods for workspace generation with uncertainty are presented. The first method is based on the calculation of positive wire tensions derived from the static force/moment balance. The second method is based on the direction of the wire forces applied to the mobile platform, and does not take into account the wire tensions. The proposed methods are applied for the workspace generation of two planar wire-actuated parallel manipulators.

Direct Differential Kinematics of Hybrid-Chain Manipulators Including Singularity and Stability Analyses

1994 ◽  
Vol 116 (2) ◽  
pp. 614-621 ◽  
Author(s):  
Yong-Xian Xu ◽  
D. Kohli ◽  
Tzu-Chen Weng
Keyword(s):  
Stability Index ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Static Force ◽  
Force Analysis ◽  
Kinematic Singularity ◽  
Numerical Examples ◽  
Transformation Matrices ◽  
Unstable Configuration ◽  
Direct Kinematics

A general formulation for the differential kinematics of hybrid-chain manipulators is developed based on transformation matrices. This formulation leads to velocity and acceleration analyses, as well as to the formation of Jacobians for singularity and unstable configuration analyses. A manipulator consisting of n nonsymmetrical subchains with an arbitrary arrangement of actuators in the subchain is called a hybrid-chain manipulator in this paper. The Jacobian of the manipulator (called here the system Jacobian) is a product of two matrices, namely the Jacobian of a leg and a matrix M containing the inverse of a matrix Dk, called the Jacobian of direct kinematics. The system Jacobian is singular when a leg Jacobian is singular; the resulting singularity is called the inverse kinematic singularity and it occurs at the boundary of inverse kinematic solutions. When the Dk matrix is singular, the M matrix and the system Jacobian do not exist. The singularity due to the singularity of the Dk matrix is the direct kinematic singularity and it provides positions where the manipulator as a whole loses at least one degree of freedom. Here the inputs to the manipulator become dependent on each other and are locked. While at these positions, the platform gains at least one degree of freedom, and becomes statically unstable. The system Jacobian may be used in the static force analysis. A stability index, defined in terms of the condition number of the Dk matrix, is proposed for evaluating the proximity of the configuration to the unstable configuration. Several illustrative numerical examples are presented.

Structure Strength Analysis on a Steel Chimney Outer Wall with Three Spiral Guide Plates

2014 ◽  
Vol 513-517 ◽  
pp. 2625-2628
Author(s):  
Xu Lei Deng ◽  
Jia Ning He ◽  
Chao Zhang
Keyword(s):  
Flexural Strength ◽  
Fluid Mechanics ◽  
Outer Wall ◽  
Wind Loads ◽  
Strength Analysis ◽  
Structure Stability ◽  
Static Force ◽  
Force Analysis ◽  
Structure Strength ◽  
Ansys Workbench

Study on a steel chimney outer wall with three spiral guide plates in this paper. Research the steel chimney structure stability and static force analysis under wind loads by using ANSYS Workbench and CFX fluid mechanics modular. To prove the steel chimney with three spiral guide plates structure is more safe and stable than the old steel chimney. Provides a new transformation basis of the steel chimney as the ratio of height to diameter is large and low flexural strength.

Comparative Static Force Analysis of Molar Distalization by a Novel Sliding Rod Microscrew Implantation Jig and Direct Traction

2015 ◽  
Vol 5 (6) ◽  
pp. 493-498
Author(s):  
Yanfeng Li ◽  
Ning Wang ◽  
Yongjin Lu ◽  
Pan Zeng ◽  
Xianglong Zeng ◽  
...  
Keyword(s):  
Static Force ◽  
Force Analysis ◽  
Molar Distalization

Investigation of Wire Failure Effect on Stiffness Maps of Planar Wire-Actuated Parallel Manipulators

2010 ◽  
Author(s):  
Amir Moradi ◽  
Leila Notash
Keyword(s):  
Differential Form ◽  
Stiffness Matrix ◽  
Parallel Manipulators ◽  
Static Force ◽  
Moment Equations ◽  
Complete Form ◽  
The Wire

In the work presented, the complete form of stiffness of planar wire-actuated parallel manipulators is formulated. The differential form of the static force and moment equations is used to formulate the symmetric stiffness matrix of the manipulator. Stiffness maps over the workspace of manipulators about and along different directions are developed and the effect of wire failure on the stiffness maps is investigated. Some strategies for retrieving the lost stiffness after the wire failure are discussed. The effects of the presented strategies on stiffness maps over the workspace of example planar wire-actuated manipulators are presented.

Study of three-dimensional unsteady Oseen flow

1978 ◽  
Vol 86 (4) ◽  
pp. 609-622 ◽  
Author(s):  
S. Murata ◽  
Y. Miyake ◽  
Y. Tsujimoto ◽  
F. Yamamoto
Keyword(s):  
Flow Field ◽  
External Force ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Applied Force ◽  
Two Dimensional ◽  
Uniform Velocity ◽  
Pressure Fields ◽  
Oseen Flow ◽  
Impulsive Pressure

In the present paper, it is intended to give the elementary solutions of three-dimensional unsteady Oseen flow when unsteady concentrated lift and/or drag is applied in the flow field. It is shown that the pressure fields due to concentrated impulsive lift and/or drag can be represented by an impulsive pressure doublet in the direction of the applied force and the corresponding velocity fields by diffusing free doublets in the direction of the external force that are shed from the location of the force application and convected downstream with otherwise uniform velocity. It is also confirmed that combination of the elementary solutions given in the present paper yields the two-dimensional ones.

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