scholarly journals Discussion: “A Four-Bar Linkage Adjustable for Variable Straight Line Motions” (Tao, D. C., and Amos, L. G., 1965, ASME J. Eng. Ind., 87, pp. 287–289)

1965 ◽  
Vol 87 (3) ◽  
pp. 289-289
Author(s):  
Kurt Hain
Keyword(s):  
Straight Line ◽  
Four Bar Linkage

scholarly journals Optimal synthesis of a four-bar linkage by method of controlled deviation

2004 ◽  
Vol 31 (3-4) ◽  
pp. 265-280 ◽  
Author(s):  
Radovan Bulatovic ◽  
Stevan Djordjevic
Keyword(s):  
Objective Function ◽  
Optimal Synthesis ◽  
Straight Line ◽  
Individual Comparison ◽  
Four Bar Linkage ◽  
The Given ◽  
Initial Selection ◽  
Selection Of ◽  
Process Calculation ◽  
Made In

This paper considers optimal synthesis of a four-bar linkage by method of controlled deviations. The advantage of this approximate method is that it allows control of motion of the coupler in the four-bar linkage so that the path of the coupler is in the prescribed environment around the given path on the segment observed. The Hooke-Jeeves?s optimization algorithm has been used in the optimization process. Calculation expressions are not used as the method of direct searching, i.e. individual comparison of the calculated value of the objective function is made in each iteration and the moving is done in the direction of decreasing the value of the objective function. This algorithm does not depend on the initial selection of the projected variables. All this is illustrated on an example of synthesis of a four-bar linkage whose coupler point traces a straight line, i.e. passes through sixteen prescribed points lying on one straight line. .

Synthesis of a Large Oscillation Four-Bar Mechanism

1997 ◽  
Author(s):  
Gloria K. Starns ◽  
Donald R. Flugrad
Keyword(s):  
Reduced Gradient Method ◽  
Large Oscillation ◽  
Oscillation Mechanism ◽  
Straight Line ◽  
Transmission Angle ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient ◽  
Angular Oscillations ◽  
Four Bar Linkage ◽  
Effective Transmission

Abstract This paper demonstrates procedures implemented for the synthesis of a four-bar mechanism that produces large angular oscillations of the output member while maintaining effective transmission angles. The mechanisms are modeled as being driven by a force applied at the coupler link. Additionally this force’s line of action is constrained to occur along an approximate straight line. This research was conducted out of the need for a device that is capable of retraction of the horizontal tool bar housed on the back of a tractor. The tool bars accommodate the implements required to accomplish the numerous tasks of the farmer, i.e. row markers, sprayer arms, planters, etc. Upon retraction of the tool bar so that it is parallel to ground, the appropriate tools are lowered to their working position. As the length of these bars increases, a savings of time and increased productivity is realized. Kurt Hain makes the following observation regarding large oscillation mechanisms in [1]: “It would be very difficult to solve this problem with one four-bar linkage, because it is difficult to design a four-bar linkage having such a large oscillation of a crank without running into problems of poor transmission angle characteristics; it might be possible to use linkages in combinations with gears, but this would make the mechanism more expensive, less efficient, and probably noisier.” In this study simulated annealing, a genetic algorithm and the generalized reduced gradient method are used to produce mechanisms with large angular oscillations of the output member and transmission angles that vary by as little as 20° from 90°. A comparative analysis of each of the optimization procedures is presented with observations regarding the efficacy of each method in the solution of the large oscillation mechanism.

Equations for Four-Bar Line-Envelopes

1981 ◽  
Vol 103 (4) ◽  
pp. 743-749 ◽  
Author(s):  
K. H. Hunt ◽  
E. F. Fichter
Keyword(s):  
The Other ◽  
Straight Line ◽  
Sliding Joint ◽  
Line Equation ◽  
Four Bar Linkage ◽  
Sliding Joints

A line-equation (in tangential coordinates) is derived for the envelope of a general straight line attached to the coupler of a planar hinged four-bar linkage. Since a line can be identified with an axis of relative translation parallel to a sliding joint, the study of how lines move in a mechanism has practical potential. Nevertheless the emphasis here is on the geometry of the line-envelopes, and some envelopes are plotted both as samples of what can be obtained and to exemplify some of the properties which they possess. Towards the end of the paper all the other forms of planar four-bar linkage, namely those in which one or two sliding joints replace hinges, are examined, and their envelope-equations are presented.

Synthesis and Analysis of a Chebyschev’s Straight Line Four-Bar Linkage for Generating a Minimum Jerk Velocity Profile

2014 ◽  
Author(s):  
Evagoras G. Xydas
Keyword(s):  
Velocity Profile ◽  
Kinematic Chain ◽  
Mechanical Constraints ◽  
Minimum Jerk ◽  
Straight Line ◽  
Wide Range ◽  
Spatio Temporal ◽  
Line Trajectory ◽  
Four Bar Linkage ◽  
Input Torque

The interaction between human and passive, constraint-based path generating mechanisms has been scarcely studied. When it comes to rehabilitation robots, output trajectories and/or forces are achieved mainly as a result of actuation on all joints, since they form an open kinematic chain. On the other end, there exists a wide range of mechanisms that can trace complex trajectories primarily due to mechanical constraints in their topology and structure. Probably the simplest example is the four bar linkage, a widely used 1-DOF mechanism. It consists of a driving link, a driven link, and a coupler which connects the two. As the input link rotates, each point on the coupler link traces a unique trajectory in space, called a coupler curve. Ideally, the linkage dimensions can be chosen so that a near-natural hand trajectory is generated for a specific task. As a first step, in this work a straight line generating four-bar mechanism, namely the Chebyshev’s linkage is considered for generating a natural bell-shaped velocity profile, as prescribed by the Minimum-Jerk-Model. Initially the mechanism is synthesized for producing a straight line trajectory of a desired length. Kinematic and kinetostatic analysis is performed in order to determine the required input torque necessary for achieving the desired spatio-temporal profile. The main objective is to determine whether this input torque can approximated by a series of linear torsional springs that can be installed on the pivoted side of the input link.

Computerized Synthesis of Straight-Line Four-Bar Linkages From Inflection Circle Properties

1977 ◽  
Vol 99 (3) ◽  
pp. 610-614
Author(s):  
J. M. Simo´n
Keyword(s):  
Digital Computer ◽  
Selection Method ◽  
Interest Points ◽  
Straight Line ◽  
Four Bar Linkage

The instantaneous property of the inflection circle corresponding to a four-bar linkage is used in the present paper to obtain points of the coupler with significant straight-line paths. These points are the interest points (IP) of the coupler, the existence and properties of which are demonstrated here using a digital computer to solve the developed equations that define the IP’s. This led us to propose a computerized trial and selection method of synthesizing straight-line four-bar linkages with new steps—the determination of IP’s and their paths—which will, we hope, shorten considerably the time it used to take to obtain the desired results of a particular problem.

A Four-Bar Linkage Adjustable for Variable Straight Line Motions

1965 ◽  
Vol 87 (3) ◽  
pp. 287-289 ◽  
Author(s):  
D. C. Tao ◽  
L. G. Amos
Keyword(s):  
Line Segments ◽  
Straight Line ◽  
Graphical Technique ◽  
Four Bar Linkage

A flexible graphical technique is presented to synthesize a four-bar linkage with an adjustable fixed pivot to satisfy a specified angle between two straight line segments traced by a coupler point.

Generic Models for Designing Dwell Mechanisms: A Novel Kinematic Design of Stirling Engines as an Example

1991 ◽  
Vol 113 (4) ◽  
pp. 446-450 ◽  
Author(s):  
S. Kota
Keyword(s):  
Design Models ◽  
Circular Arc ◽  
Generic Models ◽  
Straight Line ◽  
Stirling Engines ◽  
Finite Set ◽  
Single Input ◽  
Motion Characteristics ◽  
Generic Design ◽  
Four Bar Linkage

The desirable motion characteristics of mechanisms are so implicit that they are difficult to express analytically. Our design methodology involves development of generic design models through abstractions of entire emotion characteristics. We have developed a finite set of generic models (for straight-line, circular-arc, and dwell mechanisms) that represents the entire design space in the sense that a given design specification falls under at least one of the generic design models. This paper presents the generic design models for four-bar straight-line, circular arc, and six-bar dwell linkage mechanisms. The models presented here provide ready-made designs for many dwell applications. We have also presented a new concept in mechanisms design in which multiple coupler points on a four-bar linkage are used to drive different output dyads resulting in multiple dwell outputs. Finally, a new mechanism for the opposed piston stirling engine is presented to illustrate the use of generic design models and the application of a single-input controlling dual output motions with dwells.

Design of the Deployable Mechanisms Based on the Cardanic Motion of Planar Four-Bar Linkage

2014 ◽  
Author(s):  
Win-Bin Shieh
Keyword(s):  
Boundary Conditions ◽  
Planar Model ◽  
Building Unit ◽  
The Past ◽  
Straight Line ◽  
Systematic Methodology ◽  
Deployable Mechanism ◽  
Four Bar Linkage

A deployable mechanism is a mechanism that is designed to be repeatedly expanded and contracted without failure. Most deployable mechanisms are over-constrained mechanisms with a mobility of one. Although many deployable mechanisms had been proposed and employed in application in the past decades, few generalized methodologies for the synthesis of both planar and spatial deployable mechanisms are available. In this paper, a systematic methodology, based on the Cardanic motion of planar linkage, for the synthesis of both the spatial and planar deployable mechanisms is presented. By using the characteristics that some of the coupler points of Cardanic linkages are able to move along a straight line, a building unit mechanism that utilizes such a linkage can be extended or retracted as desired. Once the boundary conditions of the building unit mechanisms are obtained, design of an entire deployable mechanism, planar or spatial, can be fulfilled. After the design is achieved, motion of the synthesized mechanism is simulated in Pro/Engineer, and the prototype of a planar model is manufactured for the justification of this method.

The Displacement Synthesis of Four-Bar Straight-Line Mechanisms

1975 ◽  
Vol 97 (1) ◽  
pp. 322-326 ◽  
Author(s):  
R. G. Mitchiner ◽  
H. H. Mabie
Keyword(s):  
Analytical Method ◽  
Functional Relationship ◽  
Straight Line ◽  
Crank Angle ◽  
Four Bar Linkage ◽  
Crank Mechanism

This paper presents an analytical method for synthesizing a four-bar linkage from a slider-crank mechanism using the cubic of stationary curvature of the slider crank. A coupler point on the resulting linkage will generate an approximate straight line, and the functional relationship between the displacement of the coupler point and the crank angle will be the same as the relation of slider displacement to crank angle of the original slider crank.

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