Coordination of Coupler-Point Positions and Crank Rotations in Connection With Roberts’ Configuration

1969 ◽  
Vol 91 (1) ◽  
pp. 55-65 ◽  
Author(s):  
E. A. Dijksman
Keyword(s):  
Point Position ◽  
Uniform Velocity ◽  
Center Point ◽  
Straight Line ◽  
Crank Angle ◽  
Straight Line Mechanism

In this paper a geometrical solution is given to the problem of finding four-bar linkages having 5 given coupler-point positions coordinated with 4 given crank angles. It may also be possible to find solutions if one given coupler-point position together with a given crank angle, corresponding to this position, is replaced by two given link lengths. It has been found thus far that four-bar linkages, satisfying the stated conditions, are easy to obtain if the problem is related to Roberts’ law. To get a view of the possibilities, the degenerations of cognate circle-point curves and cognate center-point curves, linked to each other by the configuration (CR) of Roberts, are investigated. As an example at the end of the paper a straight-line mechanism has been designed so that the coupler point moves along this line with an approximately uniform velocity.

Design and Development of a Novel Infant Surgical Table for 4-DOF Patient Manipulation

2007 ◽  
Author(s):  
Kimberly Ryland ◽  
Carl A. Nelson ◽  
Thomas Hejkal
Keyword(s):  
Premature Infants ◽  
Laser Photocoagulation ◽  
Occupational Injury ◽  
Quality Care ◽  
Blood Vessel Development ◽  
Locking Mechanism ◽  
Straight Line ◽  
Vessel Development ◽  
Straight Line Mechanism ◽  
Standard Table

Retinopathy of Prematurity, caused by abnormal blood vessel development in the retina of premature infants, is a leading cause of childhood blindness. It is treated using laser photocoagulation. Current methods require the surgeon to assume awkward standing positions, which can result in injury to the surgeon if repeated often. To assist surgeons in providing quality care and prevent occupational injury, a new infant surgical table was designed. The engineered solution is an attachment to a standard surgical table, saving cost and space. This takes advantage of the adjustable height and tilt provided by the standard table, while 360° rotation designed into the attachment allows the surgeon to sit during surgery. The critical cords and tubes are routed through the attachment to avoid pulling and kinking. A four-bar locking mechanism allows easy attachment to standard medical railing. Finally, a straight line mechanism provides positive locking of the rotation, allowing precise positioning of the infant.

Mathematical Model for Face-Hobbed Straight Bevel Gears

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Yi-Pei Shih
Keyword(s):  
Mathematical Model ◽  
Bevel Gear ◽  
Tooth Contact Analysis ◽  
Rolling Circle ◽  
High Productivity ◽  
Bevel Gears ◽  
Straight Line ◽  
Base Circle ◽  
Straight Line Mechanism ◽  
Straight Lines

Face hobbing, a continuous indexing and double-flank cutting process, has become the leading method for manufacturing spiral bevel gears and hypoid gears because of its ability to support high productivity and precision. The method is unsuitable for cutting straight bevel gears, however, because it generates extended epicycloidal flanks. Instead, this paper proposes a method for fabricating straight bevel gears using a virtual hypocycloidal straight-line mechanism in which setting the radius of the rolling circle to equal half the radius of the base circle yields straight lines. This property can then be exploited to cut straight flanks on bevel gears. The mathematical model of a straight bevel gear is developed based on a universal face-hobbing bevel gear generator comprising three parts: a cutter head, an imaginary generating gear, and the motion of the imaginary generating gear relative to the work gear. The proposed model is validated numerically using the generation of face-hobbed straight bevel gears without cutter tilt. The contact conditions of the designed gear pairs are confirmed using the ease-off topographic method and tooth contact analysis (TCA), whose results can then be used as a foundation for further flank modification.

Slider-Cranks as Compatibility Linkages for Parametrizing Center-Point Curves

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
David H. Myszka ◽  
Andrew P. Murray
Keyword(s):  
Direct Method ◽  
Center Point ◽  
Crank Angle ◽  
Point Curve ◽  
A Direct Method

In synthesizing a planar 4R linkage that can achieve four positions, the fixed pivots are constrained to lie on a center-point curve. It is widely known that the curve can be parametrized by a 4R compatibility linkage. In this paper, a slider-crank is presented as a suitable compatibility linkage to generate the center-point curve. Furthermore, the center-point curve can be parametrized by the crank angle of a slider-crank linkage. It is observed that the center-point curve is dependent on the classification of the slider-crank. Lastly, a direct method to calculate the focus of the center-point curve is revealed.

Straight-Line Mechanisms as One Building Element of Small Precise Robotic Devices

2014 ◽  
Vol 613 ◽  
pp. 96-101 ◽  
Author(s):  
Jaroslav Hricko
Keyword(s):  
Compliant Mechanisms ◽  
Building Blocks ◽  
Linear Motion ◽  
Kinematics Analysis ◽  
Positioning Accuracy ◽  
Building Element ◽  
Revolute Joints ◽  
Straight Line ◽  
Robotic Devices ◽  
Straight Line Mechanism

Small precise robotic devices, working on principle of compact compliant mechanisms, must meet the conditions to high positioning accuracy what mean moving in straight-line too. But, compliant mechanisms are usually produced by equivalent of revolute joints, therefore in design of small robotic devices is necessary apply knowledge from design of one type of specialized mechanisms – straight-line mechanisms. This paper presents some straight-line mechanism and its applications to design of some small precise robotic devices. According to kinematics analysis most known straight-line mechanisms are evaluated for their application in compliant mechanisms. Such devices are transformed to flexure structures. Consequently, these devices are important building blocks to design some linear-motion stages and/or micro-grippers.

Slider Cranks as Compatibility Linkages for Parameterizing Center Point Curves

2009 ◽  
Author(s):  
David H. Myszka ◽  
Andrew P. Murray
Keyword(s):  
Direct Method ◽  
Center Point ◽  
Crank Angle ◽  
Point Curve ◽  
A Direct Method

In synthesizing a planar 4R linkage that can achieve four positions, the fixed pivots are constrained to lie on a center-point curve. It is widely known that the curve can be parameterized by a 4R compatibility linkage. In this paper, a slider crank is presented as a suitable compatibility linkage to generate the centerpoint curve. Further, the center-point curve can be parametrized by the crank angle of a slider crank linkage. It is observed that the center-point curve is dependent on the classification of the slider crank. Lastly, a direct method to calculate the focus of the center-point curve is revealed.

On Dimension Synthesis of Hart’s Inversor III Straight-Line Mechanism As a Precision Robotic End-of-Arm Tool

2019 ◽  
Author(s):  
Ming Z. Huang
Keyword(s):  
Flexible Manufacturing ◽  
Flexible Manufacturing Systems ◽  
High Performance ◽  
Manufacturing Systems ◽  
Analytical Approach ◽  
Industrial Robot ◽  
Mechanical Advantage ◽  
Design Considerations ◽  
Straight Line ◽  
Straight Line Mechanism

Abstract In flexible manufacturing systems, straight line motions are often required in part handling, assembly, cutting, sealing, or welding operations. Rather than using a high performance industrial robot to execute the path directly, employment of a less precise robot outfitted with an end-of-arm tool comprising an exact straight line mechanism could be more effective in both performance and in cost. Exact straight line mechanisms with pin connections are easy to manufacture and assemble, in comparison to those realized by translational joints where alignment of linear axes or surface could be problematic. Such an issue becomes even more difficult when relatively large stroke and/or high precision of straight line motion is required. In this paper, a study of the kinematic characteristics of a special class of exact straight line mechanisms, Hart’s Inversor Type III, with emphasis toward dimension synthesis, is presented. An analytical approach for sizing the link lengths with respect to a desirable straight line stroke constraint is developed and illustrated with examples. Also presented are stiffness and mechanical advantage characteristics for additional design considerations.

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