Analysis of the Conditions for the Contactless Movement of Eccentric Freewheel Mechanisms

2021 ◽  
pp. 3-9
Author(s):  
A.V. Kalinin
Keyword(s):  
Load Capacity ◽  
Kinematic Chain ◽  
Radial Clearance ◽  
Geometrical Parameters ◽  
Kinematic Chains ◽  
Geometric Conditions ◽  
Free Running ◽  
Technical Systems ◽  
Radial Gap ◽  
The Relationship

Freewheel mechanisms are used in kinematic chains of technical systems of a various functionality. When such mechanisms freewheeling, it is necessary to ensure that there is no contact of their working elements to reduce friction losses and wear. At the same time, it is necessary to ensure the minimum value of the idling angle affecting the accuracy and response time of the kinematic chain in which the mechanism is installed. The task of analyzing and determining the geometric conditions allowing ensuring a radial gap between the working elements of the eccentric freewheel mechanisms with free-running engagement has been set. To solve this problem, a design scheme is proposed and a mathematical model describing the relationship between the geometrical parameters of the mechanism is obtained. The nature of the influence of the basic geometric parameters (eccentricity, radial clearance, modulus, etc.) on the value of the idling angle is established. It is shown that when designing, the values of the module and the gap should be chosen as the minimum permissible, taking into account the load capacity and the assembly conditions. The eccentricity can be assigned based on the requirements of the manufacturing technology.

scholarly journals Influence of lower leg myofascial kinematic chains on flat feet development of children 7-14 years old

2019 ◽  
Vol 5 (2) ◽  
pp. 28 ◽  
Author(s):  
A. Danyschuk
Keyword(s):  
Experimental Studies ◽  
Kinematic Chain ◽  
Motor Units ◽  
Biomechanical Properties ◽  
Flat Foot ◽  
Kinematic Chains ◽  
Flat Feet ◽  
The Relationship ◽  
Possible Cause ◽  
Anthropometric Study

<p><strong>The aim of the work </strong>is to study the biomechanical properties of the myo-fascial kinematic chain "foot-shin" of children of 7-14 years old with non-fixed and clinically expressed flat-footedness.</p><p><strong>Material and methods</strong>. The study involved 14 children with flat-footedness of grades I-II and 6 children with flat-foot deformity of the foot and 20 children who only had functional disorders of the foot. An anthropometric study of the foot was carried out, electrophysiological indicators of the muscles of the leg were determined, and plantograms were analyzed.</p><p><strong>Results</strong>. The study found a correlation between the indicators of the anatomical and functional state of the foot and the imbalance of the frequency-amplitude indices of the ipsi and contralateral muscles within one link of the myofacial kinematic chain, may be important as one of the factors that contribute to the development of flatfoot. This is confirmed by other indicators and indicate a decrease in the height of the longitudinal arch, a decrease in the metatarsal and heel angles of the arch of the foot. Such changes have a pronounced relationship with age. The results of the work indicate that a possible cause of flattening of the vaulted apparatus of the foot is not only the weakness of its joint-ligament-muscular system, but also above the located kinematic segment - the tibia. The correlation analysis revealed the relationship between the indicators of the development of the anatomical and biomechanical components of the foot and the characteristics of the electromyographic indicators of the muscles of the leg in children 7-14 years old. As a result of a comprehensive study, it was found that during this period of ontogenesis in the formation of flatfoot such electromyographic indicators as frequency-amplitude characteristics of action potentials of motor units of the long and posterior tibial muscles, as well as their tone imbalance, take on major importance.</p><p><strong>Conclutions</strong>. Experimental studies have established that the registered changes in the articular components of the foot of children 7-14 years old lead to a change in the electromyographic parameters of the muscles of the leg, which are involved in the formation of the initial sections of myo-fascial kinematic chains.</p>

A Strategy for Geometric Error Characterization in Multi-Axis Machine Tool by Use of a Laser Tracker

2014 ◽  
Vol 615 ◽  
pp. 22-31 ◽  
Author(s):  
Sergio Aguado ◽  
Jorge Santolaria ◽  
David Samper ◽  
Juan Jose Aguilar Martín
Keyword(s):  
Machine Tool ◽  
Kinematic Model ◽  
Kinematic Chain ◽  
Geometric Error ◽  
Laser Tracker ◽  
Geometric Errors ◽  
Kinematic Chains ◽  
Error Characterization ◽  
Machine Tool Accuracy ◽  
The Relationship

This paper aims to present different methods of volumetric verification in long range machine toll with lineal and rotary axes using a commercial laser tracker as measurement system. This method allows characterizing machine tool geometric errors depending on the kinematic of the machine and the work space available during the measurement time. The kinematic of the machine toll is affected by their geometric errors, which are different depending on the number and type of movement axes. The relationship between the various geometrical errors is different from relationship obtained in machine tool whit only lineal axes. Therefore, the identification strategy should be different. In the same way, the kinematic chain of the machine tool determines determines the position of the laser tracker and available space for data capture. This paper presents the kinematic model of several machine tools with different kinematic chains use to improve the machine tool accuracy of each one by volumetric verification. Likewise, the paper thus presents a study of: the adequacy of different nonlinear optimization strategies depending on the type of axis and the usable space available.

The Systemic Research on Loop Characteristics of Planar Kinematic Chains and Its Applications

2005 ◽  
Author(s):  
H. F. Ding ◽  
Z. Huang ◽  
Y. Cao
Keyword(s):  
Degree Sequence ◽  
Kinematic Chain ◽  
Loop Analysis ◽  
Topological Graph ◽  
Type Analysis ◽  
Kinematic Chains ◽  
Relationship Of ◽  
The Relationship ◽  
Basic Loop ◽  
Isomorphism Identification

Based on the array representation of loop in topological graph of kinematic chains, this paper proposes two basic loop operations. Their existent conditions and properties of the two operations are also researched. In further loop analysis we discuss the important concepts including the independent loop, canonical degree-sequence and perimeter topological graph. Two Theorems deal with the relationship of loops. Based on above basic theory some important applications are given, such as the isomorphism identification based on the loop set concept, the detection of the rigid sub-chains in a kinematic chain and the type analysis of freedom of kinematic chains.

scholarly journals A joint–joint matrix representation of planar kinematic chains with multiple joints and isomorphism identification

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401877840 ◽  
Author(s):  
Wei Sun ◽  
Jianyi Kong ◽  
Liangbo Sun
Keyword(s):  
Matrix Representation ◽  
Kinematic Chain ◽  
Chain Structure ◽  
Kinematic Chains ◽  
Essential Step ◽  
Matrix Description ◽  
The Matrix ◽  
Chain Synthesis ◽  
The Relationship ◽  
Isomorphism Identification

The synthesis of the kinematic chain needs to obtain the information of the kinematic chain accurately and comprehensively. Isomorphism identification is an essential step in kinematic chain synthesis. In this article, a novel isomorphism determination method of planar kinematic chains with multiple joints based on joint–joint matrix description was proposed. First, a joint–joint matrix is presented to describe the kinematic chain, which can uniquely represent the kinematic chain structure. Then links and joints information were extracted from the matrix. And the link code and joint code were introduced to represent the link attributes and joint attributes, respectively. Furthermore, the standardization rules of joint–joint matrix are proposed. Isomorphism of kinematic chain is identified by comparing links, joints, and matrices. And the relationship between the links and the joints corresponding to the isomorphic kinematic chain is determined. Finally, the examples demonstrate that the method is novel and efficient.

Structure Based Grading of Kinematic Chains

2014 ◽  
Vol 575 ◽  
pp. 501-506 ◽  
Author(s):  
Shubhashis Sanyal ◽  
G.S. Bedi
Keyword(s):  
Structural Properties ◽  
Structural Property ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Kinematic Chains ◽  
Structural Differences ◽  
The Individual ◽  
Independent Loops

Kinematic chains differ due to the structural differences between them. The location of links, joints and loops differ in each kinematic chain to make it unique. Two similar kinematic chains will produce similar motion properties and hence are avoided. The performance of these kinematic chains also depends on the individual topology, i.e. the placement of its entities. In the present work an attempt has been made to compare a family of kinematic chains based on its structural properties. The method is based on identifying the chains structural property by using its JOINT LOOP connectivity table. Nomenclature J - Number of joints, F - Degree of freedom of the chain, N - Number of links, L - Number of basic loops (independent loops plus one peripheral loop).

scholarly journals Relations Between Safety and Security in Technical Systems

2007 ◽  
Vol 3 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Zbigniew Smalko
Keyword(s):  
Decision Maker ◽  
Machine System ◽  
System A ◽  
The Subject ◽  
Technical Systems ◽  
Machine Control ◽  
The Relationship

Relations Between Safety and Security in Technical Systems The subject of this paper deals with the relationship between safety and security of the man - machine system. In the above system a man can act both as a decision - maker and operator. His desired psychophysical efficiency lies in the undertaking the correct decisions as well as in the skilful machine control and operating.

Kinematic Geometry of Wheeled Vehicle Systems

1996 ◽  
Author(s):  
S. V. Sreenivasan ◽  
P. Nanua
Keyword(s):  
Geometric Approach ◽  
Companion Paper ◽  
Kinematic Chains ◽  
Uneven Terrain ◽  
Geometric Conditions ◽  
Kinematic Study ◽  
Vehicle Systems ◽  
Motion Characteristics ◽  
The One ◽  
Wheeled Vehicles

Abstract This paper addresses instantaneous motion characteristics of wheeled vehicles systems on even and uneven terrain. A thorough kinematic geometric approach which utilizes screw system theory is used to investigate vehicle-terrain combinations as spatial mechanisms that possess multiple closed kinematic chains. It is shown that if the vehicle-terrain combination satisfies certain geometric conditions, for instance when the vehicle operates on even terrain, the system becomes singular or non-Kutzbachian — it possesses finite range mobility that is different from the one obtained using Kutzbach criterion. An application of this geometric approach to the study of rate kinematics of various classes of wheeled vehicles is also included. This approach provides an integrated framework to study the kinematic effects of varying the vehicle and/or terrain geometric parameters from their nominal values. In addition, design enhancements of existing vehicles are suggested using this approach. This kinematic study is closely related to the force distribution characteristics of wheeled vehicles which is the subject of the companion paper [SN96].

Design of a Variable-Mobility Linkage Using the Bohemian Dome

2018 ◽  
Author(s):  
P. C. López-Custodio ◽  
J. S. Dai
Keyword(s):  
Configuration Space ◽  
Kinematic Chains ◽  
Paper Folding ◽  
First Time ◽  
The Relationship

The properties of the Bohemian dome are studied and it is found that for a particular type of Bohemian dome two different parameterizations based on the translation of circles can be obtained for the same surface, therefore, two different hybrid kinematic chains can be designed to generate the same Bohemian dome. These surface generators are reconfigurable and can generate two different surfaces each. Parameterizations for the secondary surfaces are obtained and studied. These hybrid kinematic chains are used to design a kinematotropic linkage with a total of 27 motion branches in its configuration space. The singularities in the configuration space are also determined using the properties of the surfaces. The resultant linkage offers an explanation of Wholhart’s queer-square linkage other than paper folding. The relationship between the properties of self-intersections in generated surfaces and the configuration space of the generator linkage is studied for the first time leading to the description of motion branches related to self-intersections of generated surfaces.

Combined Graph Layout Algorithms for Automated Sketching of Kinematic Chains

2012 ◽  
Author(s):  
Martín A. Pucheta ◽  
Nicolás E. Ulrich ◽  
Alberto Cardona
Keyword(s):  
Computational Cost ◽  
Kinematic Chain ◽  
Initial Position ◽  
Graph Representation ◽  
Combinatorial Algorithms ◽  
Graph Layout ◽  
Kinematic Chains ◽  
Aesthetic Characteristics ◽  
Edge Crossings ◽  
Independent Loops

The graph layout problem arises frequently in the conceptual stage of mechanism design, specially in the enumeration process where a large number of topological solutions must be analyzed. Two main objectives of graph layout are the avoidance or minimization of edge crossings and the aesthetics. Edge crossings cannot be always avoided by force-directed algorithms since they reach a minimum of the energy in dependence with the initial position of the vertices, often randomly generated. Combinatorial algorithms based on the properties of the graph representation of the kinematic chain can be used to find an adequate initial position of the vertices with minimal edge crossings. To select an initial layout, the minimal independent loops of the graph can be drawn as circles followed by arcs, in all forms. The computational cost of this algorithm grows as factorial with the number of independent loops. This paper presents a combination of two algorithms: a combinatorial algorithm followed by a force-directed algorithm based on spring repulsion and electrical attraction, including a new concept of vertex-to-edge repulsion to improve aesthetics and minimize crossings. Atlases of graphs of complex kinematic chains are used to validate the results. The layouts obtained have good quality in terms of minimization of edge crossings and maximization of aesthetic characteristics.

A Novel Method for Constructing Multi-Mode Deployable Polyhedron Mechanisms Using Symmetric Spatial RRR Compositional Units

2018 ◽  
Author(s):  
Jieyu Wang ◽  
Xianwen Kong
Keyword(s):  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Single Loop ◽  
Kinematic Chains ◽  
The Third ◽  
Motion Modes ◽  
3D Printed ◽  
Novel Method ◽  
Multi Mode ◽  
Motion Mode

A novel construction method is proposed to construct multimode deployable polyhedron mechanisms (DPMs) using symmetric spatial RRR compositional units, a serial kinematic chain in which the axes of the first and the third revolute (R) joints are perpendicular to the axis of the second R joint. Single-loop deployable linkages are first constructed using RRR units and are further assembled into polyhedron mechanisms by connecting single-loop kinematic chains using RRR units. The proposed mechanisms are over-constrained and can be deployed through two approaches. The prism mechanism constructed using two Bricard linkages and six RRR limbs has one degree-of-freedom (DOF). When removing three of the RRR limbs, the mechanism obtains one additional 1-DOF motion mode. The DPMs based on 8R and 10R linkages also have multiple modes, and several mechanisms are variable-DOF mechanisms. The DPMs can switch among different motion modes through transition positions. Prototypes are 3D-printed to verify the feasibility of the mechanisms.

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