Dynamic Characteristics of Spatial Mechanisms

1969 ◽  
Vol 91 (1) ◽  
pp. 228-233 ◽  
Author(s):  
E. J. Givens ◽  
J. C. Wolford
Keyword(s):  
Linkage Analysis ◽  
Dynamic Characteristics ◽  
Energy Method ◽  
Planar Mechanisms ◽  
Matrix Methods ◽  
Digital Computation ◽  
Spatial Mechanisms ◽  
Spatial Linkages

An energy method given by Quinnfor determining the dynamic characteristics of planar mechanisms under the action of displacement-related forces is extended to spatial linkages. These linkages may, in addition, be subjected to time-related forces or to velocity-related damping forces. Recently developed matrix methods are used in the linkage analysis resulting in a method well suited to digital computation.

A Method for Type Synthesis of Mechanisms Using Phase Diagrams

1994 ◽  
Author(s):  
Sio-Hou Lei ◽  
Ying-Chien Tsai
Keyword(s):  
Phase Diagram ◽  
Degrees Of Freedom ◽  
Practical Application ◽  
Type Synthesis ◽  
Planar Mechanisms ◽  
Simple Loop ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Spatial Mechanisms ◽  
Synthesis Of Mechanisms

Abstract A method for synthesizing the types of spatial as well as planar mechanisms is expressed in this paper by using the concept of phase diagram in metallurgy. The concept represented as a type synthesis technique is applied to (a) planar mechanisms with n degrees of freedom and simple loop, (b) spatial mechanisms with single degree of freedom and simple loop, to enumerate all the possible mechanisms with physically realizable kinematic pairs. Based on the technique described, a set of new reciprocating mechanisms is generated as a practical application.

Energy Method for Determining Dynamic Characteristics of Mechanisms

1949 ◽  
Vol 16 (3) ◽  
pp. 283-288
Author(s):  
B. E. Quinn
Keyword(s):  
Dynamic Characteristics ◽  
Energy Method ◽  
Mechanical Systems ◽  
Direct Approach ◽  
Graphical Methods ◽  
Applied Forces ◽  
Complex Mechanical Systems

Abstract Two types of problems are dealt with in the paper which are involved in the design of mechanisms required to have specified dynamic characteristics: (1) Determination of applied forces required to produce specified dynamic characteristics. (2) Determination of the dynamic characteristics which will result from the application of known forces. While graphical methods may be used in the solution of type (1) problems involving more or less complex mechanical systems, they do not afford a direct approach to type (2) problems. The energy method which will be outlined can be applied in either case, although this paper will be primarily concerned with the determination of the dynamic characteristics which result when a known force is applied to a given mechanism.

A New Method and Automatic Generation for Dynamic Analysis of Complex Planar Mechanisms Based on the Ordered Single-Opened-Chains

1994 ◽  
Author(s):  
Jian-Qing Zhang ◽  
Ting-Li Yang
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Equation ◽  
Automatic Generation ◽  
The Other ◽  
New Method ◽  
Complex Mechanism ◽  
Planar Mechanisms ◽  
Spatial Mechanisms ◽  
General Dynamic

Abstract This work presents a new method for kinetostatic analysis and dynamic analysis of complex planar mechanisms, i.e. the ordered single-opened-chains method. This method makes use of the ordered single-opened chains (in short, SOC,) along with the properties of SOC, and the network constraints relationship between SOC,. By this method, any planar complex mechanism can be automatically decomposed into a series of the ordered single-opened chains and the optimal structural decomposition route (s) can be automatically selected for dynamic analysis, the paper present the dynamic equation which can be used to solve both the kinetostatic problem and the general dynamic problem. The main advantage of the proposed approach is the possibility to reduce the number of equations to be solved simultaneously to the minimum, and its high automation as well. The other advantage is the simplification of the determination of the coefficients in the equations, and thus it maybe result in a much less time-consuming algorthem. The proposed approach is illustrated with three examples. The presented method can be easily extended to the dynamic analysis of spatial mechanisms.

A Transmission Index for Spatial Mechanisms

1973 ◽  
Vol 95 (2) ◽  
pp. 589-597 ◽  
Author(s):  
G. Sutherland ◽  
B. Roth
Keyword(s):  
Error Characteristics ◽  
General Index ◽  
Spatial Mechanisms ◽  
Transmission Index ◽  
Quality Of Motion ◽  
Spatial Linkages

A general index of the quality of motion transmission for spatial mechanisms is developed using the theory of screws. This index is shown to be related to the mechanical error possible in a linkage. A method for synthesizing spatial linkages with desirable motion transmission and mechanical error characteristics is developed and examples are shown for the RGGR linkage.

Stiffness characterization of a 3-PPR planar parallel manipulator with actuation compliance

2014 ◽  
Vol 229 (12) ◽  
pp. 2291-2302 ◽  
Author(s):  
Guanglei Wu ◽  
Shaoping Bai ◽  
Jørgen Kepler
Keyword(s):  
Eigenvalue Problem ◽  
Stiffness Matrix ◽  
Parallel Manipulator ◽  
Rotational Stiffness ◽  
Planar Mechanisms ◽  
Spatial Mechanisms ◽  
Generalized Eigenvalue ◽  
Stiffness Model ◽  
Planar Parallel Manipulator

This paper investigates the stiffness of a compliant planar parallel manipulator. Instead of establishing stiffness matrix directly for planar mechanisms, we adopt the modeling approach for spatial mechanisms, which allows us to derive two decoupled homogeneous matrices, corresponding to the translational and rotational stiffness. This is achieved by resorting to the generalized eigenvalue problem, through which the eigenscrew decomposition is implemented to yield six screw springs. The principal stiffnesses and their directions are then identified from the eigenvalue problem of the two separated submatrices. In addition, the influence of the nonlinear actuation compliance to the manipulator stiffness is investigated, and the established stiffness model is experimentally verified.

Microvibration Model Development and Validation of a Cantilevered Reaction Wheel Assembly

2012 ◽  
Vol 226-228 ◽  
pp. 133-137 ◽  
Author(s):  
Zhe Zhang ◽  
Guglielmo S. Aglietti ◽  
Wei Jia Ren
Keyword(s):  
Dynamic Characteristics ◽  
Energy Method ◽  
Model Development ◽  
Broadband Noise ◽  
Empirical Modeling ◽  
Model Parameters ◽  
Test Results ◽  
Reaction Wheel ◽  
Disturbance Model ◽  
Development And Validation

Reaction wheel assemblies are one of the most important microvibration sources on typical modern satellites. In this paper microvibrations induced by a cantilevered reaction wheel assembly are modelled and validated against microvibration test results. The disturbance model is developed using energy method. A microvibration measurement platform is designed to measure its disturbances. Disturbance test results are analyzed in detail. The peculiar dynamic characteristics such as nonlinearity and high damping of harmonic responses in the test results are discussed. Estimations of damping values used in the disturbance model are introduced. A new method developed to model harmonic excitations is discussed. Furthermore, novel methods to identify harmonics and extract model parameters from test results are presented. The empirical modeling method developed for broadband noise excitations are also introduced and validated.

scholarly journals Dynamic Characteristics of Planar Mechanisms with Clearances

1978 ◽  
Vol 21 (152) ◽  
pp. 303-308 ◽  
Author(s):  
Hiroshi SHIMOJIMA ◽  
Kiyoshi OGAWA ◽  
Kazutoshi MATSUMOTO
Keyword(s):  
Dynamic Characteristics ◽  
Planar Mechanisms

Experimental and Finite Element Modal Analyses of Planar Mechanisms With Three-Dimensional Geometries

1998 ◽  
Vol 120 (3) ◽  
pp. 401-403 ◽  
Author(s):  
A. Smaili ◽  
I. Bagci
Keyword(s):  
Finite Element ◽  
Dynamic Modeling ◽  
Dynamic Characteristics ◽  
Three Dimensional ◽  
Modal Testing ◽  
Element Solution ◽  
Considerable Influence ◽  
Planar Mechanisms ◽  
Isoparametric Finite Element ◽  
Testing Techniques

This article presents the results of numerical and experimental modal analyses of a planar four-bar (4R) mechanism having three dimensional geometry due to the offsets between its links. An experimental mechanism is built and modern modal testing techniques are used. A five-node isoparametric finite element is developed and used to model the mass and flexibility of the links and joints, link offsets, and drive and load shafts. The results obtained from the finite element solution matched closely the experimental results, a testimony to the accuracy of the proposed element. The results indicated that link offsets have considerable influence on the dynamic characteristics of a mechanism system and should be considered in dynamic modeling of planar mechanisms.

New Complex-Number Form of the Cubic of Stationary Curvature in a Computer-Oriented Treatment of Planar Path-Curvature Theory for Higher-Pair Rolling Contact

1982 ◽  
Vol 104 (1) ◽  
pp. 233-238 ◽  
Author(s):  
G. N. Sandor ◽  
A. G. Erdman ◽  
L. Hunt ◽  
E. Raghavacharyulu
Keyword(s):  
Complex Number ◽  
Rate Of Change ◽  
Rolling Contact ◽  
Planar Mechanisms ◽  
Digital Computation ◽  
Complex Arithmetic ◽  
Moving Plane ◽  
Curvature Theory ◽  
Path Curvature ◽  
Number Form

New complex number forms of the Euler-Savary Equation (ESE) for higher-pair rolling contact planar mechanisms were derived in a former paper by the authors. The present work, based on the former, deals with the derivation of the cubic of stationary curvature (CSC) in complex-vector form, suitable for digital computation. The CSC or Burmester’s circlepoint curve and its conjugate, the centerpoint curve for four infinitesimally close positions of the moving plane requires taking into account not only the curvature but also the rate of change of curvature of the rolling centrodes in the immediate vicinity of the position considered. The analytical procedure based on the theory developed in the present paper, when programmed for digital computation using complex arithmetic, takes care of the algebraic signs automatically, without the need for observing traditional sign conventions. The analysis is applicable to both higher-pair and lower-pair planar mechanisms. An example using the complex-number approach illustrates this.

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