Singularity Analysis of a Parallel Hip Joint Simulator Based on Grassmann Line Geometry

2012 ◽  
Vol 48 (17) ◽  
pp. 29 ◽  
Author(s):  
Gang CHENG
Keyword(s):  
Hip Joint ◽  
Singularity Analysis ◽  
Line Geometry ◽  
Grassmann Line Geometry ◽  
Hip Joint Simulator

scholarly journals Configuration and singularity analysis of a parallel hip joint simulator based on the forward kinematics

2016 ◽  
Vol 40 (15-16) ◽  
pp. 7281-7292 ◽  
Author(s):  
Gang Cheng ◽  
Yang Li ◽  
Gabriel Lodewijks ◽  
Yusong Pang ◽  
Xianlei Shan
Keyword(s):  
Hip Joint ◽  
Singularity Analysis ◽  
Forward Kinematics ◽  
Hip Joint Simulator

Combinatorial Method for Characterizing Singular Configurations in Parallel Mechanisms

2015 ◽  
Author(s):  
Avshalom Sheffer ◽  
Offer Shai
Keyword(s):  
Singularity Analysis ◽  
Parallel Mechanisms ◽  
Line Geometry ◽  
Combinatorial Method ◽  
Combinatorial Characterization ◽  
Singular Configurations ◽  
Grassmann Line Geometry ◽  
2D And 3D ◽  
Grassmann Cayley Algebra

The paper presents a method for finding the different singular configurations of several types of parallel mechanisms/robots using the combinatorial method. The main topics of the combinatorial method being used are: equimomental line/screw, self-stresses, Dual Kennedy theorem and circle, and various types of 2D and 3D Assur Graphs such as: triad, tetrad and double triad. The paper introduces combinatorial characterization of 3/6 SP and compares it to singularity analysis of 3/6 SP using Grassmann Line Geometry and Grassmann-Cayley Algebra. Finally, the proposed method is applied for characterizing the singular configurations of more complex parallel mechanisms such as 3D tetrad and 3D double-triad.

Development of a novel two-limbed parallel mechanism having Schönflies motion

2014 ◽  
Vol 229 (1) ◽  
pp. 136-154 ◽  
Author(s):  
Sung Mok Kim ◽  
Kyoosik Shin ◽  
Byung-Ju Yi ◽  
Wheekuk Kim
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Model ◽  
Singularity Analysis ◽  
Short Description ◽  
High Potential ◽  
Haptic Device ◽  
Line Geometry ◽  
Grassmann Line Geometry ◽  
Schönflies Motion ◽  
Very High

This paper introduces a novel parallel mechanism having Schönflies motion. The mechanism consists of only two RRPaR-type limbs. After a short description of its structure, its position analysis is conducted and its screw-based kinematic model is derived. Next, its singularity analysis is performed via Grassmann line geometry and then its optimal kinematic characteristics are examined with respect to workspace size and isotropy property. The results show that the proposed parallel mechanism has a very high potential to be used as a manipulator or a haptic device. A prototype of this mechanism was developed and tested to corroborate its performance.

Singularity Analysis of 5-RPRRR Parallel Mechanisms via Grassmann Line Geometry

2009 ◽  
Author(s):  
Mehdi Tale Masouleh ◽  
Cle´ment Gosselin
Keyword(s):  
Jacobian Matrix ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
General Mechanism ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Line Geometry ◽  
Singular Configurations ◽  
Highly Nonlinear ◽  
Grassmann Line Geometry

This paper investigates the singular configurations of five-degree-of-freedom parallel mechanisms generating the 3T2R motion and comprising five identical legs of the RPUR type. The general mechanism was recently revealed by performing the type synthesis for symmetrical 5-DOF parallel mechanisms. In this study, some simplified designs are proposed for which the singular configurations can be predicted by means of the so-called Grassmann line geometry. This technique can be regarded as a powerful tool for analyzing the degeneration of the Plu¨cker screw set. The main focus of this contribution is to predict the actuation singularity, for a general and simplified design, without expanding the determinant of the inverse Jacobian matrix (actuated constraints system) which is highly nonlinear and difficult to analyze.

On the Design of Singularity-Free Cable-Driven Parallel Mechanism Based on Grassmann Geometry

2012 ◽  
Author(s):  
Yu Zou ◽  
Yuru Zhang ◽  
Yaojun Zhang
Keyword(s):  
Parallel Mechanism ◽  
Jacobian Matrix ◽  
Singularity Analysis ◽  
Geometric Meaning ◽  
Parallel Mechanisms ◽  
Line Geometry ◽  
Singular Configurations ◽  
Negative Effect ◽  
Grassmann Line Geometry ◽  
Grassmann Geometry

This paper deals with the design of singularity-free cable-driven parallel mechanism. Due to the negative effect on the performance, singularities should be avoided in the design. The singular configurations of mechanisms can be numerically determined by calculating the rank of its Jacobian matrix. However, this method is inefficient and non-intuitive. In this paper, we investigate the singularities of planar and spatial cable-driven parallel mechanisms using Grassmann line geometry. Considering cables as line vectors in projective space, the singularity conditions are identified with clear geometric meaning which results in useful method for singularity analysis of the cable-driven parallel mechanisms. The method is applied to 3-DOF planar and 6-DOF spatial cable-driven mechanisms to determine their singular configurations. The results show that the singularities of both mechanisms can be eliminated by changing the dimensions of the mechanisms or adding extra cables.

Biotribological behaviour of Vitamin E-blended highly cross-linked UHMWPE in a hip joint simulator

2016 ◽  
Vol 68 (5) ◽  
pp. 548-553 ◽  
Author(s):  
Guomei Chen ◽  
Zifeng Ni ◽  
Shanhua Qian ◽  
Yongwu Zhao
Keyword(s):  
Wear Resistance ◽  
Vitamin E ◽  
Hip Joint ◽  
Oxidative Degradation ◽  
Test Environment ◽  
Content Type ◽  
Artificial Hip Joint ◽  
Hip Simulator ◽  
Directional Motion ◽  
Hip Joint Simulator

Purpose The purposes of this paper are to investigate the biotribological behaviour of Vitamin E-blended highly cross-linked ultra-high molecular weight polyethylene (HXL-UHMWPE) under multi-directional motion by using a CUMT II artificial joint hip simulator and compare it with HXL-UHMWPE and conventional UHMWPE. Design/methodology/approach The biotribological behaviour of conventional, highly cross-linked and Vitamin E-blended highly cross-linked UHMWPE acetabular cups counterfaced with CoCrMo alloy femoral head under multi-directional motion were investigated by using CUMT-II artificial hip joint simulator for one-million walking cycles. The test environment was at 36.5 ± 0.5°C and 25 per cent bovine serum was used as lubricant. A Paul cycle load with a peak of 784 N was applied; the motion and loading were synchronized at 1 Hz. Findings The wear resistance of Vitamin E-blended highly cross-linked UHMWPE was significantly higher than that of highly cross-linked and conventional UHMWPE. The wear marks observed from the worn surface of UHMWPE were multi-directional, with no dominant wear direction. Only abrasion occurred on the surface of Vitamin E-blended highly cross-linked UHMWPE, while yielding and accumulated plastic flow processes occurred on the surface of conventional UHMWPE and flaking-like facture and abrasion occurred on the surface of highly cross-linked UHMWPE. Originality/value Besides the prevention of oxidative degradation, blending with Vitamin E can also reduce the incidence of fatigue crack occurred in the surface layer of HXL-UHMWPE samples. Therefore, the wear resistance of HXL-UHMWPE under multi-directional motion can be further enhanced by blending with Vitamin E.

Sign in / Sign up

Export Citation Format

Share Document