Stiffness Analysis of 3-RPR Planar Parallel Mechanism to the Stiffness Control

2009 ◽  
Vol 16-19 ◽  
pp. 786-790 ◽  
Author(s):  
Shu Jun Li ◽  
Clément Gosselin
Keyword(s):  
Stiffness Matrix ◽  
Parallel Mechanism ◽  
Stiffness Analysis ◽  
Numerical Examples ◽  
Stiffness Control ◽  
Conservative Congruence Transformation ◽  
Stiffness Characteristics ◽  
External Forces ◽  
Congruence Transformation

The analytical stiffness equations of the 3-RPR planar parallel mechanism are derived in this paper based on the Conservative Congruence Transformation (CCT) stiffness matrix proposed in [1-3]. Stiffness maps of the 3-RPR mechanism are plotted in order to show the behaviour of the stiffness with and without external forces. The stiffness characteristics of the mechanism are analyzed and discussed in details. Numerical examples show that the stiffness in x and in y are well balanced, while the stiffness in tends to be lower.

Stiffness Analysis of 6-SPS Parallel Manipulator

2012 ◽  
Vol 468-471 ◽  
pp. 1220-1223
Author(s):  
Shu Jun Li ◽  
Qiao Ling Meng
Keyword(s):  
External Force ◽  
Stiffness Matrix ◽  
Parallel Manipulator ◽  
Joint Stiffness ◽  
Stiffness Analysis ◽  
Conservative Congruence Transformation ◽  
External Forces ◽  
And Behavior ◽  
Congruence Transformation

The analytical stiffness equations of 6-SPS spatial parallel manipulator were deduced based on the Conservative Congruence Transformation (CCT) stiffness matrix. The stiffness mappings of the 6-SPS manipulator were given to show the change and behavior of the stiffness with external forces acted on the manipulator. The results show that the stiffness of the 6-SPS manipulator is configuration dependent, and proportional to the actuating forces and joint stiffness. The stiffness is correlates not only to the magnitude of external forces but also the direction of the external force acted upon.

A stiffness analysis for a hybrid parallel-serial manipulator

Robotica ◽  
2004 ◽  
Vol 22 (5) ◽  
pp. 567-576 ◽  
Author(s):  
Giuseppe Carbone ◽  
Marco Ceccarelli
Keyword(s):  
Numerical Investigation ◽  
Performance Index ◽  
Stiffness Matrix ◽  
Mechanical Design ◽  
General Procedure ◽  
Design Parameters ◽  
Serial Manipulators ◽  
Stiffness Analysis ◽  
Hybrid Manipulator ◽  
Stiffness Characteristics

In this paper a hybrid parallel-serial manipulator, named as CaHyMan (Cassino Hybrid Manipulator), is analyzed in term of stiffness characteristics as a specific example of a general procedure for analyzing stiffness of parallel-serial manipulators. A formulation is presented to deduce the stiffness matrix as a function of the most important stiffness and design parameters of the mechanical design. A formulation is proposed for a stiffness performance index by using the obtained stiffness matrix. A numerical investigation has been carried out on the effects of design parameters and fundamental results are discussed in the paper.

Stiffness Modeling of the Soft-Finger Contact in Robotic Grasping

2004 ◽  
Vol 126 (4) ◽  
pp. 646-656 ◽  
Author(s):  
Abdul Ghafoor ◽  
Jian S. Dai ◽  
Joseph Duffy
Keyword(s):  
Stiffness Matrix ◽  
Screw Theory ◽  
Contact Stiffness ◽  
Point Contact ◽  
Elastic Model ◽  
Point Contacts ◽  
Stiffness Analysis ◽  
Stiffness Properties ◽  
Congruence Transformation ◽  
Soft Finger

This paper investigates the soft-finger contact by presenting the contact with a set of line springs based on screw theory, reveals the rotational effects, and identifies the stiffness properties of the contact. An elastic model of a soft-finger contact is proposed and a generalized contact stiffness matrix is developed by applying the congruence transformation and by introducing stiffness mapping of the line springs in translational directions and rotational axes. The effective stiffnesses along these directions and axes are hence obtained and the rotational stiffnesses are revealed. This helps create a screw representation of a six-dimensional soft-finger contact and produce an approach of analyzing and synthesizing a robotic grasp without resorting to the point contact representation. The correlation between the rotational stiffness, the number of equivalent point contacts and the number of equivalent contours is given and the stiffness synthesis is presented with both modular and direct approaches. The grasp thus achieved from the stiffness analysis contributes to both translational and rotational restraint and the stiffness matrix so developed is proven to be symmetric and positive definite. Case studies are presented with a two-soft-finger grasp and a three-soft-finger grasp. The grasps are analyzed with a general stiffness matrix which is used to control the fine displacements of a grasped object by changing the preload on the contact.

Constraint Stiffness Construction and Decomposition of a SPS Orthogonal Parallel Mechanism

2015 ◽  
Author(s):  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Stiffness Matrix ◽  
Parallel Mechanism ◽  
Reciprocal Relationship ◽  
Stiffness Analysis ◽  
Matrix Partition ◽  
Comparison Results ◽  
Analysis And Synthesis ◽  
Physical Prototype ◽  
Type Constraint ◽  
Line Type

This paper investigates both stiffness analysis and synthesis problems using a physical prototype of one SPS orthogonal parallel mechanism. This parallel mechanism is supported with line-type constraint limbs. In the stiffness analysis, a reciprocal relationship between motions and wrenches is used to design layouts of constraint limbs and construct the corresponding stiffness matrix. In the stiffness synthesis, the developed stiffness matrix is decomposed to obtain configurations of constraint limbs based on existing synthesis algorithms, including direct-recursion and matrix-partition approaches. It is revealed the line-vector based matrix-partition approach can establish an one-to-one correspondence between synthesized results and constraint limbs of the parallel mechanism. Subsequently both types of synthesis approaches are applied to decomposing the developed constraint stiffness matrix. The comparison results suggest the modified matrix-partition approach can obtain decomposed constraint limbs exactly the same as those used to construct the stiffness matrix.

Stiffness Analysis and Experimental Validation for the 6-Dof Jaw Opening-Closing Training Parallel Robot WY-5 (Waseda Yamanashi 5)

2004 ◽  
Vol 16 (6) ◽  
pp. 570-578
Author(s):  
Giuseppe Carbone ◽  
◽  
Hideaki Takanobu ◽  
Marco Ceccarelli ◽  
Atsuo Takanishi ◽  
...  
Keyword(s):  
Stiffness Matrix ◽  
Experimental Validation ◽  
Mouth Opening ◽  
Experimental Tests ◽  
Parallel Robot ◽  
Stiffness Analysis ◽  
Jaw Opening ◽  
Proposed Model ◽  
Stiffness Characteristics ◽  
Opening And Closing

In this paper a mouth opening and closing training robot named as WY-5 (Waseda Yamanashi version 5) is analyzed in terms of stiffness characteristics. Basic models and a formulation are proposed in order to deduce the stiffness matrix as a function of the most important stiffness parameters of the WY-5 architecture. A numerical simulation is carried out as based on the proposed formulation. Experimental tests are carried out in order to validate the proposed model that can be used for design/control purposes in order to improve the performance of WY-5.

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