Kinematic Analysis and Simulation of the Tri-Prism Deployable Structure

2015 ◽  
Vol 799-800 ◽  
pp. 1183-1187
Author(s):  
Huai Dong Zhou ◽  
Peng Zhen ◽  
Wu Sheng Chou
Keyword(s):  
Kinematic Analysis ◽  
Screw Theory ◽  
Mechanical Design ◽  
Complex Mechanism ◽  
Drive Mode ◽  
Kinematic Equation ◽  
Deployable Structure ◽  
In Series ◽  
The Relationship ◽  
Theoretical Results

The Tri-prism deployable structure is a complex mechanism which consists of six deployable structure units in series. All deployable structure units have the similar movements; the screw theory is used to establish the kinematic equation of each unit and the entire tri-prism deployable structure. Meanwhile, the motion stability, drive mode and mechanical design of the tri-prism deployable structure have been comprehensively researched. Finally, extensive simulations in ADAMS have been conducted to obtain the relationship between the motions of ends and inputs, which are further compared with theoretical results.

Design and Kinematic Analysis of a 3RRlS Metamorphic Parallel Mechanism for Large-Scale Reconfigurable Space Multifingered Hand

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Chong Zhao ◽  
Hongwei Guo ◽  
Rongqiang Liu ◽  
Zongquan Deng ◽  
Bing Li
Keyword(s):  
Shape Memory Alloy ◽  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Large Scale ◽  
Screw Theory ◽  
Kinematic Equation ◽  
Aerospace Application ◽  
Parasitic Motion ◽  
Geometric Conditions ◽  
In Series

Capturing noncooperative targets in space has great prospects for aerospace application. In this work, the knuckle unit of a large-scale reconfigurable space multifingered hand (LSRSMFH) for multitask requirements is studied. A plurality of knuckle units is connected in series to form a finger of the LSRSMFH. First, the lockable spherical (lS) joint, a new metamorphic joint that can function as a Hooke (lS1) or spherical (lS2) joint and is driven by shape memory alloy (SMA) material, is proposed. Based on the lS joint, this paper presents a new metamorphic parallel mechanism (MPM) (i.e., 3RRlS MPM), which has four configurations, namely, 3RRlS1, 3RRlS2, 2RRlS1-RRlS2, and 2RRlS2-RRlS1 configuration. The degree-of-freedom (DOF), overconstraint, and parasitic motion of the 3RRlS MPM are analyzed using screw theory, of which the DOF can be changed from 1 to 3. The 3RRlS1 configuration has a virtual constraint, and the 3RRlS2 configuration has parasitic motions. The results indicate that the mechanism motion screws can qualitatively represent the mechanism parasitic motions, and it is verified by deriving the kinematic equation of the 3RRlS MPM based on its spatial geometric conditions, the workspace of the 3RRlS MPM is further solved. The kinematic analysis indicates that the 3RRlS MPM can realize the folding, capturing, and reconfiguring conditions of the LSRSMFH.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

The Roles of Features and Abstraction in Mechanical Design

1994 ◽  
Author(s):  
LeRoy E. Taylor ◽  
Mark R. Henderson
Keyword(s):  
Life Cycle ◽  
Engineering Design ◽  
Design Process ◽  
Design Research ◽  
Mechanical Design ◽  
Product Modeling ◽  
Product Models ◽  
Mechanical Products ◽  
Unique Framework ◽  
The Relationship

Abstract This paper describes the roles of features and abstraction mechanisms in the mechanical design process, mechanical designs, and product models of mechanical designs. It also describes the relationship between functions and features in mechanical design. It is our experience that many research efforts exist in the areas of design and product modeling and, further, that these efforts must be cataloged and compared. To this end, this paper culminates with the presentation of a multi-dimensional abstraction space which provides a unique framework for (a) comparing mechanical engineering design research efforts, (b) relating conceptual objects used in the life cycle of mechanical products, and (c) defining a product modeling space.

scholarly journals Wicksell's Problem in Local Stereology

2013 ◽  
Vol 45 (4) ◽  
pp. 925-944
Author(s):  
Ó. Thórisdóttir ◽  
M. Kiderlen
Keyword(s):  
Reference Point ◽  
Simulated Data ◽  
Domain Of Attraction ◽  
Spherical Particles ◽  
Section Profile ◽  
Particle Parameters ◽  
The Individual ◽  
The Relationship ◽  
Theoretical Results ◽  
Isotropic Random

Wicksell's classical corpuscle problem deals with the retrieval of the size distribution of spherical particles from planar sections. We discuss the problem in a local stereology framework. Each particle is assumed to contain a reference point and the individual particle is sampled with an isotropic random plane through this reference point. Both the size of the section profile and the position of the reference point inside the profile are recorded and used to recover the distribution of the corresponding particle parameters. Theoretical results concerning the relationship between the profile and particle parameters are discussed. We also discuss the unfolding of the arising integral equations, uniqueness issues, and the domain of attraction relations. We illustrate the approach by providing reconstructions from simulated data using numerical unfolding algorithms.

scholarly journals The Transport of Salt and Water across Isolated Rat Ileum

1967 ◽  
Vol 50 (3) ◽  
pp. 695-727 ◽  
Author(s):  
T. W. Clarkson
Keyword(s):  
Active Transport ◽  
Transport Processes ◽  
Irreversible Processes ◽  
Pressure Gradients ◽  
Ion Flow ◽  
Chemical Gradients ◽  
In Series ◽  
Frictional Coefficients ◽  
The Relationship ◽  
Active Channel

The flows of sodium, potassium, and chloride under electrical and chemical gradients and of salt and water in the presence of osmotic pressure gradients are described by phenomenological equations based on the thermodynamics of irreversible processes. The aim was to give the simplest possible description, that is to postulate the least number of active transport processes and the least number of separate pathways across the intestine. On this basis, the results were consistent with the following picture of the intestine: Two channels exist across this tissue, one allowing only passive transport of ions and the other only active. In the passive channel, the predominant resistance to ion flow is friction with the water in the channel. The electroosmotic flow indicates that the passive channel is lined with negative fixed charged groups having a surface charge density of 3000 esu cm-2. The values of the ion-water frictional coefficients, and the relationship between ionic concentrations and flows indicate that the passive channel is extracellular. The active channel behaves as two membranes in series, the first membrane being semipermeable but allowing active transport of sodium, and the second membrane being similar to the passive channel. Friction with the ions in the second "membrane" is the predominant resistance to water flow.

scholarly journals Conflict-Directed Backjumping Revisited

2001 ◽  
Vol 14 ◽  
pp. 53-81 ◽  
Author(s):  
X. Chen ◽  
P. Van Beek
Keyword(s):  
Constraint Satisfaction Problems ◽  
Local Consistency ◽  
Backtracking Search ◽  
Arc Consistency ◽  
Look Ahead ◽  
Variable Ordering ◽  
Look Back ◽  
The Look ◽  
The Relationship ◽  
Theoretical Results

In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classified as look-ahead schemes and look-back schemes. Unfortunately, look-ahead and look-back schemes are not entirely orthogonal as it has been observed empirically that the enhancement of look-ahead techniques is sometimes counterproductive to the effects of look-back techniques. In this paper, we focus on the relationship between the two most important look-ahead techniques---using a variable ordering heuristic and maintaining a level of local consistency during the backtracking search---and the look-back technique of conflict-directed backjumping (CBJ). We show that there exists a ``perfect'' dynamic variable ordering such that CBJ becomes redundant. We also show theoretically that as the level of local consistency that is maintained in the backtracking search is increased, the less that backjumping will be an improvement. Our theoretical results partially explain why a backtracking algorithm doing more in the look-ahead phase cannot benefit more from the backjumping look-back scheme. Finally, we show empirically that adding CBJ to a backtracking algorithm that maintains generalized arc consistency (GAC), an algorithm that we refer to as GAC-CBJ, can still provide orders of magnitude speedups. Our empirical results contrast with Bessiere and Regin's conclusion (1996) that CBJ is useless to an algorithm that maintains arc consistency.

scholarly journals The relationship between the sovereignty of member states and the supernationality of international organizations

2020 ◽  
pp. 349-353
Author(s):  
Olga Shpakovych ◽  
Sofia Penkovska
Keyword(s):  
International Organizations ◽  
The State ◽  
International Organization ◽  
State Sovereignty ◽  
Member States ◽  
The Relationship ◽  
Theoretical Results ◽  
The Eu

The article presents the result of theoretical and practical study of the relationship between state sovereignty and supranationalityof international organizations. In particular, it is determined that the phenomenon of supranationality of international organizations isderived from state sovereignty and acts as its external law. It has been shown that, in view of this, supranationality is limited becauseit arises through the exercise of sovereignty by states, and, accordingly, is limited by the amount of state sovereignty exercised by states.The relevant mechanism has also been studied on the example of the functioning of the European Union.Regarding the theoretical results, the following should be noted. First, it was proved that despite the different approaches of scho -lars to the understanding of supranationality, definitions of this concept and the separation of its features (properties), in each case,supranationality is a direct realization of state sovereignty. At the same time, the realization of state sovereignty in relation to such pro -perties of international organizations as supranational is primary, and supranationality in this case is derivative. In addition, the phenomenonof supranationality of international organizations due to the fact that it is derived is limited, because supranationality arisesthrough the exercise of sovereignty by states, and, accordingly, is limited by the amount of state sovereignty exercised by states. Thatis why when analyzing the relationship between the supranationality of international organizations and state sovereignty, one cannotconsider the priority of one of the two, because supranationality is in essence a manifestation of state sovereignty.Regarding the practical results, the author considers it appropriate to emphasize that both the regional international organization –the EU was studied, and, at the same time, it was proved that all theoretical provisions were reflected in practice, in particular, envisagedfunctions, goals and the tasks of the studied international organizations are limited in scope by the manifestation of sovereignty shownby states, similar to the regulations issued by organizations. Another indication that the state can exercise its sovereignty in any case isthat there is an effective and transparent procedure for leaving these organizations

The Vibration Isolation Effect Research of the Floating Raft Isolation System Based on the Adjustable Flexibility of Foundation

2013 ◽  
Vol 819 ◽  
pp. 115-119 ◽  
Author(s):  
Hui Wang ◽  
Ze Yu Weng ◽  
Gan Xiang ◽  
Bo Lu ◽  
Hong Gang Ding ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Test System ◽  
Isolation Effect ◽  
Isolation System ◽  
Elastic Beams ◽  
Floating Raft ◽  
Marine Engineering ◽  
Flexible Foundation ◽  
The Relationship ◽  
Theoretical Results

The floating raft isolation system is widely used in the field of marine engineering for its vibration isolation effect. Along with the application of light thinning structure of the ship, the flexibility of foundation of floating raft isolation system makes the vibration isolation effect vary widely between the practical floating raft isolation system and its theoretical results. In order to research the vibration isolation effect of the floating raft isolation system on different flexibility of foundation, the floating raft isolation system with flexible foundation is designed in this paper, and the adjustable flexibility of foundation is achieved by using elastic beams. With simulation and analysis of test system in ADAMS, the results of the relationship between flexibility and vibration isolation effect are obtained.

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