Vector analysis of spatial mechanism — (IV) dynamics of spatial mechanisms

1983 ◽  
Vol 4 (6) ◽  
pp. 875-884
Author(s):  
Yu Xin
Keyword(s):  
Vector Analysis ◽  
Spatial Mechanism ◽  
Spatial Mechanisms

On the shaft locations of two contra-rotating counterweights for balancing spatial mechanisms

1997 ◽  
Vol 211 (8) ◽  
pp. 567-578 ◽  
Author(s):  
S-T Chiou ◽  
J-C Tzou
Keyword(s):  
Root Mean Square ◽  
Mean Square ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
Crank Mechanism ◽  
Frequency Term ◽  
Shaking Moment

It has been shown in a previous work that a frequency term of the shaking force of spatial mechanisms, whose hodograph is proved to be an ellipse, can be eliminated by a pair of contrarotating counterweights. In this work, it is found that the relevant frequency term of the shaking moment is minimized if the balancing shafts are coaxial at the centre of a family of ellipsoids, called isomomental ellipsoids, with respect to (w.r.t.) any point on an ellipsoid, as is also the root mean square (r.m.s.) of the relevant frequency term of the shaking moment. It can also be minimized even though the location of either shaft, but not both, is chosen arbitrarily on a plane. The location of the second shaft is then determinate. In order to locate the centre, a derivation for the theory of isomomental ellipsoids of a frequency term of the shaking moment of spatial mechanisms is given. It is shown that the r.m.s. of a frequency term shaking moment of a spatial mechanism w.r.t. the concentric centre of the isomomental ellipsoids is the minimum. Examples of a seven-link 7-R spatial linkage and a spatial slider-crank mechanism are included.

Kinematic Analysis of Spatial Mechanisms by Means of Screw Coordinates. Part 2—Analysis of Spatial Mechanisms

1971 ◽  
Vol 93 (1) ◽  
pp. 67-73 ◽  
Author(s):  
M. S. C. Yuan ◽  
F. Freudenstein ◽  
L. S. Woo
Keyword(s):  
Computer Program ◽  
Kinematic Analysis ◽  
Static Force ◽  
Single Degree Of Freedom ◽  
Numerical Examples ◽  
Spatial Mechanism ◽  
Single Degree ◽  
Spatial Mechanisms ◽  
Torque Analysis ◽  
Basic Concepts

The basic concepts of screw coordinates described in Part I are applied to the numerical kinematic analysis of spatial mechanisms. The techniques are illustrated with reference to the displacement, velocity, and static-force-and-torque analysis of a general, single-degree-of-freedom spatial mechanism: a seven-link mechanism with screw pairs (H)7. By specialization the associated computer program is capable of analyzing many other single-loop spatial mechanisms. Numerical examples illustrate the results.

Integrated Kinematic and Dynamic Optimal Synthesis of Spatial Mechanisms

1987 ◽  
Author(s):  
A. J. Kakatsios ◽  
S. J. Tricamo
Keyword(s):  
Nonlinear Programming ◽  
Simultaneous Optimization ◽  
Programming Formulation ◽  
Joint Torques ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
Structural Error ◽  
Integrated Technique ◽  
Driving Torque ◽  
Shaking Moment

Abstract A novel integrated technique permitting the simultaneous optimization of kinematic and dynamic characteristics in the synthesis of spatial mechanisms is shown. The nonlinear programming formulation determines mechanism variables which simultaneously minimize the maximum values of bearing reactions, joint torques, driving torque, shaking moment, and shaking force while constraining the maximum kinematic structural error to a prescribed bound. The method is applied to the design of a path generating RRSS spatial mechanism with prescribed input link timing. Dynamic reactions in the mechanisms synthesized using the integrated technique were substantially reduced when compared to those of a mechanism synthesized to satisfy only the specified kinematic conditions.

A PHIGS-Based Graphics Input Interface for Spatial Mechanism Design

1987 ◽  
Author(s):  
B. R. Thatch ◽  
A. Myklebust
Keyword(s):  
Data Entry ◽  
Interactive Graphics ◽  
Mechanism Synthesis ◽  
Spatial Mechanism ◽  
Input Interface ◽  
New Methods ◽  
Spatial Mechanisms ◽  
Six Dof ◽  
Device Independence ◽  
Definition Of

Abstract Creation of input specifications for synthesis or analysis of spatial mechanisms can be a significant problem. A graphics preprocessor which interactively assists in the definition of spatial mechanism problems is described. New methods of depth cucing and six DOF data entry are presented. To achieve graphics device-independence, the proposed graphics standard PHIGS (Programmer’s Hierarchical Interactive Graphics System) is used. Examples of application are presented including generation of input commands for Integrated Mechanisms Program (IMP) and generation of input for spatial mechanism synthesis routines.

Solution of Topology Embryonic Graph and Topology Graph for Unified Planar-Spatial Mechanisms

2003 ◽  
Author(s):  
Lu Yi ◽  
Tatu Leinonen
Keyword(s):  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Matrix Approach ◽  
Group Approach ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
And Topology ◽  
Topology Graph ◽  
Relative Theory

An analysis matrix approach for solving an isomeric topology embryonic graph and a digital group approach for solving an isomeric topology graph of a unified planar-spatial mechanism are presented and the relative theory is discussed. Firstly, all binary links are removed from each acceptable linkage system with different degrees of freedom, many analysis matrixes are constructed, and many topology embryonic graphs of the mechanism are derived. Secondly, from an acceptable multi-element link combination of planar or spatial mechanisms, a rule for determining the isomeric topology embryonic graphs and an unreasonable topology embryonic graph is obtained. Thirdly, by considering the degree of freedom of the mechanism and the configuration of a planar or spatial mechanism, the number of binary links is determined. Finally, all removed binary links are rearranged systematically back into an isomeric topology embryonic graph, and the acceptable topology graphs of the mechanism are derived by using a digital group approach. Some illustrations show that the two approaches are simple and effective tools and can be employed to synthesize both planar and spatial mechanisms.

Numerical Phenomena of a Spatial Mechanism With Clearances

1994 ◽  
Author(s):  
Zhang Jianling ◽  
Li Zhe ◽  
Bai Shixian
Keyword(s):  
Differential Equation ◽  
Mechanical Model ◽  
Equation Of Motion ◽  
Numerical Results ◽  
Dynamic Responses ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
Steady State Responses ◽  
Set Up ◽  
State Responses

Abstract The general mechanical model of C pair with clearances is set up and used to derive the differential equation of motion of a RSCR mechanism with clearance at C pair in this paper. The numerical results are analysed and compared with the dynamic responses of the nominal RSCR mechanism. Chaotic phenomena can be seen in the numerical results, which indicate that the steady state responses may not be achievable for spatial mechanisms with clearance connections.

A PHIGS+ Model Rendering System for Simulation of Spatial Mechanisms

1991 ◽  
Author(s):  
David E. Montgomery ◽  
Mitchel J. Keil ◽  
Arvid Myklebust
Keyword(s):  
Open Loop ◽  
Interference Detection ◽  
Graphic System ◽  
Independent System ◽  
Iso Standard ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
New Ideas ◽  
Mechanism Modeling ◽  
New Algorithms

Abstract A device independent system is described for the visualization, modeling, and animation of spatial mechanisms and robots. New ideas and methods are presented to simplify the interactive specification of scene rendering and color parameters using the ISO standard for 3-D graphics, the Programmer’s Hierarchical Interactive Graphic System (PHIGS) and its extensions PHIGS+. The parallels between the PHIGS hierarchical structure and spatial mechanism modeling are described from the level of mechanism through links, joints, geometry primitives to PHIGS graphics primitives. Perception and evaluation of spatial mechanism designs are significantly improved by the use of shaded, lighted, depth cued models under animation. The method is coupled to new algorithms for automatic interference detection and reshaping of mechanism links to avoid collisions. The suitability of PHIGS+ for the modeling and simulation of open loop mechanisms is also described. Examples are presented for rendering and animation of spatial mechanisms on a Raster Technologies (Alliant) GX4000 workstation with a hardware based PHIGS+ graphics subsystem, UNIX, NeWS, and C.

Stereoscopic Drawings Made by Analog Computer of Three-Dimensional Surfaces Generated by Spatial Mechanism

1971 ◽  
Vol 93 (1) ◽  
pp. 239-250
Author(s):  
L. E. Torfason ◽  
F. R. E. Crossley
Keyword(s):  
Three Dimensional ◽  
Analog Computer ◽  
Ball Joint ◽  
Spatial Mechanism ◽  
Transmission Properties ◽  
Spatial Mechanisms ◽  
As If

Spatial mechanisms with up to five links and containing at least one ball joint can be solved by considering the intersection of the three dimensional surfaces which can be generated by portions of the mechanism. This paper presents a method whereby stereoscopic pairs of the surfaces can be drawn using an electronic analog computer and the figures viewed as if they were three dimensional. This results in a far better visualization of the surfaces. In many cases it can be seen what the type of intersection between surfaces is. This determines the gross motion of the mechanism, the limits of its motion, and an estimate of its transmission properties.

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