Burmester Theory for Four-Bar-Band Mechanisms

1995 ◽  
Vol 117 (1) ◽  
pp. 129-133
Author(s):  
K. Luck ◽  
K.-H. Modler
Keyword(s):  
Analytical Methods ◽  
Path Generation ◽  
Complex Vector ◽  
Vector Algebra ◽  
Flexible Application ◽  
Four Bar Linkage ◽  
Special Case ◽  
Better Than

A band mechanism includes inter alia a flexible band and a disk profile. Such a mechanism can be used for path generation better than a four-bar linkage. Also several plane positions can be realized. This paper investigates the synthesis of four-bar-band mechanisms by using complex vector algebra. Several technical tasks demonstrate the flexible application of such mechanisms. These tasks are formulated according to the well-known Burmester Theory, but with higher claims and a solution achieved by analytical methods. Furthermore, this paper demonstrates that a four-bar linkage is a special case of a four-bar-band mechanism.

Burmester-Theory for Band-Mechanisms

1992 ◽  
Author(s):  
Kurt Luck ◽  
Karl-Heinz Modler
Keyword(s):  
Analytical Methods ◽  
Path Generation ◽  
Complex Vector ◽  
Vector Algebra ◽  
Flexible Application ◽  
Four Bar Linkage ◽  
Special Case ◽  
Better Than

Abstract A band-mechanism includes inter alia a flexible band and a disk-profile. Such a mechanism can excellent be used for path-generation, better than a four-bar-linkage. Also several plane-positions additionally can be realized. This paper investigates the synthesis of four-bar-band-mechanisms by using the complex vector-algebra. Several technical tasks demonstrate the flexible application of such mechanisms. This tasks are formulated analogous to the wellknown BURMESTER-THEORY, but with higher claims and the solution is done by analytical methods. Further it is demonstrated that a four-bar-linkage is a special case of a four-bar-band-mechanism.

Synthesis and Balancing of Cam-Modulated Linkages

1987 ◽  
Author(s):  
P. Pracht ◽  
P. Minotti ◽  
M. Dahan
Keyword(s):  
Systematic Approach ◽  
Kinematic Chain ◽  
Path Generation ◽  
Industrial Manipulator ◽  
High Speeds ◽  
Structural Error ◽  
Mass Balancing ◽  
Four Bar Linkage ◽  
Robotic Applications ◽  
Class Of Functions

Abstract Linkages are inherently light, inexpensive, strong, adaptable to high speeds and have little friction. Moreover the class of functions suitable for linkage representation is large. For all these reasons numerous recent works deal with the problem of design mechanisms for robotic applications, but very often in terms of components such as gripper, transmission, balancing. We investigate a new application for linkages, using them to design industrial manipulator. The selected mechanism for this application is a four bar linkage with an adjustable lengh for exact path generation. This adjustment is performed by a track or cam which is substituted to a bar. By this mean, we define a cam-modulated linkage which possess superior accuracy potential and is capable of accomodating of industrial design restrictions. Such a kinematic chain is free from structural error for path generation and the presence of the track introduces the flexibility and versality in the usefull four bar chain. The synthesis technique of cam modulated linkage utilizes loop closure equations, envelop theory to find the centerline and the profile of the track. These techniques provide a systematic approach to the design of mechanism for path generation when extreme accuracy is required. In order to complete an contribution, we take in consideration the static balancing of the synthesized manipulator. To achieve static mass balancing we use the potential energy storage capabilities of linear springs, and integrated it with the non-linear motion of mechanism to provide an exact value of the desired counter loading functions. Examples are worked to demonstrate applications of these procedures and to illustrate the industrial potential of spring balancing and cam-modulated linkage.

An Algorithm for a Near Optimal NC Path Generation in Staircase (Lase) Traversal of Convex Polygonal Surfaces

1999 ◽  
Vol 122 (1) ◽  
pp. 182-190 ◽  
Author(s):  
S. V. Kamarthi ◽  
S. T. S. Bukkapatnam ◽  
S. Hsieh
Keyword(s):  
Rapid Prototyping ◽  
Path Length ◽  
Tool Path ◽  
Path Generation ◽  
Convex Polygons ◽  
Sweep Angle ◽  
Pocket Milling ◽  
Different Shapes ◽  
Path Lengths ◽  
Better Than

This paper presents an analytical model of the tool path for staircase traversal of convex polygonal surfaces, and an algorithm—referred to as OPTPATH—developed based on the model to find the sweep angle that gives a near optimal tool path length. The OPTPATH algorithm can be used for staircase traversal with or without (i) overlaps between successive sweep passes, and (ii) rapid traversal along edge passes. This flexibility of OPTPATH renders it applicable not only to conventional operations such as face and pocket milling, but also to other processes such as robotic deburring, rapid prototyping, and robotic spray painting. The effective tool path lengths provided by OPTPATH are compared with those given by the following two algorithms: (i) a common industrial heuristic—referred to as the IH algorithm—and (ii) an algorithm proposed by Prabhu et al. (Prabhu, P. V., Gramopadhye, A. K., and Wang, H. P., 1990, Int. J. Prod. Res., 28, No. 1, pp. 101–130) referred to as PGW algorithm. This comparison is conducted using 100 randomly generated convex polygons of different shapes and a set of seven different tool diameters. It is found that OPTPATH performs better than both the IH as well as PGW algorithms. The superiority of OPTPATH over the two algorithms becomes more pronounced for large tool diameters. [S1087-1357(00)71501-2]

Modeling of Nonlinear Viscoelastic Creep of Polycarbonate

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Wenbo Luo ◽  
Said Jazouli ◽  
Toan Vu-Khanh
Keyword(s):  
Creep Behavior ◽  
Room Temperature ◽  
Multiple Integral ◽  
Model Fit ◽  
Viscoelastic Creep ◽  
Commercial Grade ◽  
Nonlinear Viscoelastic ◽  
Schapery Model ◽  
Special Case ◽  
Better Than

AbstractThe creep behavior of a commercial grade polycarbonate was investigated in this study. 10 different constant stresses ranging from 8 MPa to 50 MPa were applied to the specimen, and the resultant creep strains were measured at room temperature. It was found that the creep could be modeled linearly below 15 MPa, and nonlinearly above 15 MPa. Different nonlinear viscoelastic models have been briefly reviewed and used to fit the test data. It is shown that the Findley model is a special case of the Schapery model, and both the Findley model and the simplified multiple integral representation are suitable for properly describing the creep behavior of the polycarbonate investigated in this paper; however, the Findley model fit the data better than the simplified multiple integral with three terms.

Eliminating Structural Error in Real-Time Adjustable Four-Bar Path Generators Using Iterative Learning Control

2004 ◽  
Author(s):  
Hong-Jen Chen ◽  
Richard W. Longman ◽  
Meng-Sang Chew
Keyword(s):  
Control Systems ◽  
Real Time ◽  
Iterative Learning Control ◽  
Learning Control ◽  
Iterative Learning ◽  
Path Generation ◽  
Structural Error ◽  
Four Bar Linkage

Fundamental concepts of Iterative Learning Control (ILC) are applied to path generating problems in mechanisms. As an illustration to such class of problems, an adjustable four-bar linkage is used. The coupler point of a four-bar traces a coupler curve that will in general deviate from the desired coupler path. Except at the precision points, the coupler curve will exhibit some structural error, which is the deviation from the specified curve. The structural error will repeat itself every cycle at exactly the same points over the range of interest. Since ILC is a methodology that was developed to handle similar repetitive errors in control systems, it is believed that it will be well served to apply it to this class of problems. Results show that ILC can be simple to implement, and it is found to be very well suited for such path generation problems.

Mechanisms of the Ancient Greek Theater

1992 ◽  
Author(s):  
Andrew D. Dimarogonas
Keyword(s):  
The Political ◽  
Path Generation ◽  
Space Travel ◽  
Ancient Greek ◽  
Machine Element ◽  
Four Bar Linkage ◽  
Indirect Information ◽  
First Time ◽  
Latin Term

Abstract The word Mechanism is a derivative of the Greek word mechane (which meant machine, more precisely, machine element) meaning an assemblage of machines. While it was used for the first time by Homer in the Iliad to describe the political manipulation, it was used with its modern meaning first in Aeschylos times to describe the stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term Deus ex machina. At the same time, the word mechanopoios, meaning the machine maker or engineer, was introduced for the man who designed, built and operated the mechane. None of these machines, made of perishable materials, is extant. However, there are numerous references to such machines in extant tragedies or comedies and vase paintings from which they can be reconstructed: They were large mechanisms consisting of beams, wheels and ropes which could raise weights up-to one ton and, in some cases, move them back-and-forth violently to depict space travel, when the play demanded it. The vertical dimensions were over 4 m while the horizontal travel could be more than 8 m. They were well-balanced and they could be operated, with some exaggeration perhaps, by the finger of the engineer. There is indirect information about the timing of these mechanisms. During the loading and the motion there were specific lines of the chorus, from which we can infer the duration of the respective operation. The reconstructed mechane is a spatial three- or four-bar linkage designed for path generation.

Synthesis of the four-bar linkage as path generation by choosing the shape of the connecting rod

2020 ◽  
Vol 234 (13) ◽  
pp. 2643-2652 ◽  
Author(s):  
SM Varedi-Koulaei ◽  
H Rezagholizadeh
Keyword(s):  
Analytical Solution ◽  
Nonlinear Equations ◽  
Linear Equations ◽  
Solution Process ◽  
Current Method ◽  
Path Generation ◽  
Connecting Rod ◽  
Complicated Process ◽  
Four Bar Linkage ◽  
Analytical Synthesis

This paper presents a method for path generation synthesis of a four-bar linkage that includes both graphical and analytical synthesis and both cases of with and without prescribed timing. The advantage of the proposed method over available techniques is that it is easier and does not need the complicated process (especially in graphical case). In an analytical solution, this method needs the solution of the linear equations, unlike the previous methods, in that they have required the solution of the nonlinear equations. Moreover, in the current method, one can choose the shape of the coupler, while, in other methods, the shape of the coupler is the result of the solution process. The proposed algorithm can be used for path generation synthesizing of a four-bar linkage for three precision points.

Analytical systems ranked by freedom from interferences.

1987 ◽  
Vol 33 (8) ◽  
pp. 1453-1458 ◽  
Author(s):  
M R Glick ◽  
K W Ryder
Keyword(s):  
Thin Film ◽  
Analytical Methods ◽  
Protein Separation ◽  
Clinical Chemical ◽  
Physical Barriers ◽  
Dialysis Membranes ◽  
Quantitative Rating ◽  
Analytical System ◽  
Rating Scheme ◽  
Better Than

Abstract We determined the effect of hemolysis, lipemia, and bilirubinemia on clinical-chemical analytical results under standardized conditions, for serum specimens prepared by us. Our purpose was to assess results obtained with 22 commonly available analytical systems. The quantitative rating scheme described is derived from the observed interference(s) divided by the number of analytical methods evaluated. The combined ranking reveals which chemistry analyzers are least affected and which are most affected by the added substances. Generally, systems that incorporate physical barriers or protein-separation steps perform better than those without thin-film layers, glass-fiber barriers, or dialysis membranes. Among the "direct" analyzers, fewer interferences are seen if appropriate "blanking" wavelengths are used, especially if a "specimen blank" absorbance is used appropriately in the analytical system. Centrifugal analyzers tended to perform poorly, according to the criteria presented here.

On the dependence structure of hitting times of univariate processes

1988 ◽  
Vol 25 (02) ◽  
pp. 355-362 ◽  
Author(s):  
Nader Ebrahimi ◽  
T. Ramalingam
Keyword(s):  
Brownian Motion ◽  
Structural Properties ◽  
Hitting Times ◽  
Dependence Structure ◽  
Special Case ◽  
New Better Than Used ◽  
Better Than

Some concepts of dependence have recently been introduced by Ebrahimi (1987) to explore the structural properties of the hitting times of bivariate processes. In this framework, the special case of univariate processes has curious features. New properties are derived for this case. Some applications to sequential inference and inequalities for Brownian motion and new better than used (NBU) processes are also provided.

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