Numerical Analysis of the Grasp Configuration of a Planar 3-DOF Linkage-Driven Underactuated Finger

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Hamed Khakpour ◽  
Lionel Birglen
Keyword(s):  
Numerical Analysis ◽  
Dynamic Simulation ◽  
Degrees Of Freedom ◽  
Joint Angles ◽  
Final Configuration ◽  
Contact Points ◽  
Novel Method ◽  
Three Degrees Of Freedom ◽  
Underactuated Finger ◽  
Simulation Package

This paper proposes a novel method to investigate the grasp sequence of an underactuated (a.k.a. adaptive) finger with three degrees of freedom but only one actuator and find its final configuration. This method considers the magnitude and the sign of the torques generated on the phalanges of the finger through the contact points. By using these torques as indices, the algorithm calculates the values of the joint angles during the grasping sequence until the finger reaches its final configuration. To illustrate the effectiveness of this method a class of a 3-DOF adaptive finger is chosen and analyzed and then, using the proposed methodology, its grasp configuration is calculated when grasping different fixed objects. Finally, simulations are repeated using a dynamic simulation package and the obtained results are compared to the proposed method. The results show that the method can properly estimate the final configuration of the grasp.

A Model of the Human Spine: Forward and Inverse Kinematics

1992 ◽  
Author(s):  
Sunil Kumar Agrawal ◽  
Siyan Li ◽  
Glen Desmier
Keyword(s):  
Range Of Motion ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Joint Angles ◽  
Human Spine ◽  
Forward And Inverse Kinematics ◽  
Position And Orientation ◽  
Three Degrees Of Freedom ◽  
Adjacent Vertebra

Abstract The human spine is a sophisticated mechanism consisting of 24 vertebrae which are arranged in a series-chain between the pelvis and the skull. By careful articulation of these vertebrae, a human being achieves fine motion of the skull. The spine can be modeled as a series-chain with 24 rigid links, the vertebrae, where each vertebra has three degrees-of-freedom relative to an adjacent vertebra. From the studies in the literature, the vertebral geometry and the range of motion between adjacent vertebrae are well-known. The objectives of this paper are to present a kinematic model of the spine using the available data in the literature and an algorithm to compute the inter vertebral joint angles given the position and orientation of the skull. This algorithm is based on the observation that the backbone can be described analytically by a space curve which is used to find the joint solutions..

The Transverse Shear Effect of a New Plate Bending Finite Element Based on the Strain Approach

2018 ◽  
Vol 35 ◽  
pp. 1-10
Author(s):  
Sifeddine Abderrahmani ◽  
Toufik Maalem ◽  
Djamal Hamadi
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Transverse Shear ◽  
Degrees Of Freedom ◽  
Close Agreement ◽  
Plate Bending ◽  
Shear Effect ◽  
Thin Plate Bending ◽  
Kirchhoff Theory ◽  
Three Degrees Of Freedom

In this paper, we present a comparative study of the transverse shear effect on the plate bending. The element used is a rectangular finite element called SBRPK (Strain Based Rectangular Plate-Kirchhoff Theory-), it used for the numerical analysis of thin plate bending, and it based on the strain approach. This element has four nodes and three degrees of freedom per node (w, θx, θy). Through the numerical applications with different loading cases and boundary conditions; the numerical results obtained are in close agreement with the analytical solution.

Dynamic Simulation of Freight Car and Lading During Impact

1977 ◽  
Vol 99 (4) ◽  
pp. 859-866 ◽  
Author(s):  
P. V. Kasbekar ◽  
V. K. Garg ◽  
G. C. Martin
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Dynamic Analysis ◽  
Dynamic Simulation ◽  
Parametric Study ◽  
Degrees Of Freedom ◽  
Impact Damage ◽  
Packaging Materials ◽  
Freight Car ◽  
Three Degrees Of Freedom

A dynamic analysis is presented to explain damage to railroad cars and ladings resulting from impacts. In the analysis, a mathematical model consisting of the car body and freight in the car is presented. Each freight element assumes three degrees of freedom for the computer simulation. A parametric study is made to establish sensitivity of car parameters and impact conditions. The study should be useful to aid in finding means for controlling impact damage and in designing packaging materials.

Numerical Analysis for Galloping of Iced Quad Bundle Conductors

2012 ◽  
Vol 226-228 ◽  
pp. 30-34
Author(s):  
Jun Yan Cai ◽  
Xi Jun Liu ◽  
Su Xia Zhang
Keyword(s):  
Numerical Analysis ◽  
Degrees Of Freedom ◽  
Damping Ratio ◽  
Simplified Model ◽  
Fluid Density ◽  
Spring Stiffness ◽  
Critical Wind Velocity ◽  
Line Path ◽  
Stiffness And Damping ◽  
Three Degrees Of Freedom

In order to attain the purpose of anti-galloping, a simplified model for iced quad bundle conductors of three degrees of freedom in vertical, horizontal and torsional directions is established by means of the Hamilton principle, in which the effect of spacers stiffness and damping is considered. Based on the model, the influence of related parameters such as fluid density, damping ratio on conductor galloping amplitude and critical wind velocity is analyzed. Simultaneously, the relation curve between elastic property of spacers and conductor galloping is obtained. The results indicate that the conductor galloping can be weakened to some degree with the proper enlargement of damping ratio, the reasonable setting of spring stiffness on spacers and the avoidance of areas such as the wind outlet and windward as much as possible when choosing the line path and so on.

Design method of planar three-degrees-of-freedom serial compliance device with desired compliance characteristics

2012 ◽  
Vol 226 (9) ◽  
pp. 2331-2344 ◽  
Author(s):  
Man Bok Hong ◽  
Yong Je Choi
Keyword(s):  
Degrees Of Freedom ◽  
Design Method ◽  
Synthesis Method ◽  
Normal Contact ◽  
Compact Size ◽  
Novel Method ◽  
Parallel Connections ◽  
Mechanical Elements ◽  
Method Analysis ◽  
Three Degrees Of Freedom

In this article, a novel method for the systematic design of a planar three-degrees-of-freedom compliance device with desired compliance characteristics is presented. For the realization of desired compliance, the synthesis method of stiffness of a planar mechanism is first derived. The compliance device may be directly realized by means of parallel connections of the synthesized springs. However, the use of several mechanical elements such as joints and guides for spring assemblies for the realization may cause significant complexity in manufacturing the compliance device with high precision and in compact size. In order to resolve the problem, the form of serial connections of three torsional springs which has the same compliance as the form of parallel connections of the synthesized line springs is proposed. The serial form of torsional springs can be physically realized by designing proper shape of the circular flexure hinge corresponding to each of the torsional springs. For the illustration of the proposed design method, a planar serial compliance device with high compliance to the normal contact force is designed and verified by finite element method analysis.

Numerical Analysis of Dynamic Coefficients for Gas Film Face Seals

2002 ◽  
Vol 124 (4) ◽  
pp. 743-754 ◽  
Author(s):  
Yuchuan Liu ◽  
Xinmin Shen ◽  
Wanfu Xu
Keyword(s):  
Numerical Analysis ◽  
Degrees Of Freedom ◽  
Axial Direction ◽  
Spiral Groove ◽  
Gas Bearings ◽  
Damping Coefficients ◽  
Face Seals ◽  
Stiffness And Damping ◽  
Three Degrees Of Freedom ◽  
Perturbation Approximation

A numerical analysis of stiffness and damping coefficients for gas film face seals in three degrees of freedom is presented in this paper. By applying small perturbation approximation, the steady and perturbed Reynolds equations, taking account of both hydrodynamic and hydrostatic effects, are obtained and solved by finite element method. Several numerical samples, including externally pressurized annular thrust gas bearings and spiral groove thrust gas bearings, validate the model and numerical algorithm. The results show that the interactions between axial and angular perturbation are negligible. Hence, in the dynamic analysis of gas film face seals, the perturbation in three degrees of freedom can be simplified as two independent ones, an axial movement and an angular wobble around two orthogonal axes perpendicular to axial direction.

Trajectory planning of redundant robots by maximizing the moving acceleration radius

Robotica ◽  
1992 ◽  
Vol 10 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Ki-Kap Kim ◽  
Yong-San Yoon
Keyword(s):  
Degrees Of Freedom ◽  
Null Space ◽  
Angular Acceleration ◽  
Sequential Algorithm ◽  
Space Operator ◽  
Joint Angles ◽  
Joint Torques ◽  
Redundant Robots ◽  
Planar Robot ◽  
Three Degrees Of Freedom

SUMMARYThe moving acceleration radius (MAR) is proposed as a local performance index quantifying the dynamic uniformity of a redundant robot. MAR can be calculated by a simple sequential algorithm, and the resolution of the redundant joint angles is obtained by maximizing MAR locally. In addition, the reduction of the joint torques is achieved by maximizing the acceleration bound in the direction of work path, while MAR is being kept at a maximum. Also a new differentiation algorithm for angular acceleration is suggested for numerical efficiency as well as accuracy, using a null space operator.A three degrees of freedom planar robot with one degree of redundancy, simulated using these algorithms for various situations, showed a marked improvement in dynamic characteristics.

scholarly journals Kinematic-Model-Free Orientation Control for Robot Manipulation Using Locally Weighted Dual Quaternions

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 76
Author(s):  
Ahmad AlAttar ◽  
Petar Kormushev
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Kinematic Model ◽  
Model Learning ◽  
Orientation Control ◽  
Dual Quaternions ◽  
Model Free ◽  
Novel Method ◽  
Model Free Controller ◽  
Three Degrees Of Freedom

Conventional control of robotic manipulators requires prior knowledge of their kinematic structure. Model-learning controllers have the advantage of being able to control robots without requiring a complete kinematic model and work well in less structured environments. Our recently proposed Encoderless controller has shown promising ability to control a manipulator without requiring any prior kinematic model whatsoever. However, this controller is only limited to position control, leaving orientation control unsolved. The research presented in this paper extends the state-of-the-art kinematic-model-free controller to handle orientation control to manipulate a robotic arm without requiring any prior model of the robot or any joint angle information during control. This paper presents a novel method to simultaneously control the position and orientation of a robot’s end effector using locally weighted dual quaternions. The proposed novel controller is also scaled up to control three-degrees-of-freedom robots.

A New Strain Based Sector Finite Element for Plate Bending Problems

2017 ◽  
Vol 31 ◽  
pp. 1-13 ◽  
Author(s):  
Sifeddine Abderrahmani ◽  
Toufik Maalem ◽  
Abdallah Zatar ◽  
Djamal Hamadi
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Plate Bending ◽  
Numerical Examples ◽  
Bending Problems ◽  
Thin Plate Bending ◽  
Three Degrees Of Freedom

The purpose of this paper is to present the formulation of a new sector finite element based on the strain approach for the numerical analysis of circular thin plate bending. The element is named SBSPK and has four nodes and three degrees of freedom per node (3 d.o.f./node). From several numerical examples, it is shown that convergence can be achieved with the use of only a small number of finite elements. The results obtained are compared with analytical and available numerical solutions.

Numerical analysis of flow-induced nonlinear vibrations of an airfoil with three degrees of freedom

2011 ◽  
Vol 49 (1) ◽  
pp. 110-127 ◽  
Author(s):  
Miloslav Feistauer ◽  
Jaromír Horáček ◽  
Martin Růžička ◽  
Petr Sváček
Keyword(s):  
Numerical Analysis ◽  
Degrees Of Freedom ◽  
Nonlinear Vibrations ◽  
Three Degrees Of Freedom
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