Design of Compliant Mechanism Microgripper Utilizing the Hoekens Straight Line Mechanism

2019 ◽  
Vol 49 (3) ◽  
pp. 20190091
Author(s):  
V. Gopal ◽  
M. S. Alphin ◽  
R. Bharanidaran
Keyword(s):  
Compliant Mechanism ◽  
Straight Line ◽  
Straight Line Mechanism

A Variable-Stiffness Straight-Line Compliant Mechanism

2015 ◽  
Author(s):  
Jeffrey C. Hawks ◽  
Mark B. Colton ◽  
Larry L. Howell
Keyword(s):  
Force Feedback ◽  
Compliant Mechanism ◽  
Variable Stiffness ◽  
Effective Length ◽  
Haptic Interface ◽  
Element Analysis ◽  
Straight Line ◽  
Rigid Body Model ◽  
Straight Line Mechanism ◽  
Force Displacement

In this research a variable-stiffness compliant mechanism was developed to generate variable force-displacement profiles at the mechanism’s coupler point. The mechanism is based on a compliant Robert’s straight-line mechanism, and the stiffness is varied by changing the effective length of the compliant links with an actuated slider. The force-deflection behavior of the mechanism was analyzed using the Pseudo-Rigid Body Model (PRBM), and two key parameters, KΘ and γ, were optimized using finite element analysis (FEA) to match the model with the measured behavior of the mechanism. The variable-stiffness mechanism was used in a one-degree-of-freedom haptic interface (force-feedback device) to demonstrate the effectiveness of varying the stiffness of a compliant mechanism. Unlike traditional haptic interfaces, in which the force is controlled using motors and rigid links, the haptic interface developed in this work displays haptic stiffness via the variable-stiffness compliant mechanism. One of the key features of the mechanism is that the inherent return-to-zero behavior of the compliant mechanism was used to provide the stiffness feedback felt by the user. A prototype haptic interface was developed capable of simulating the force-displacement profile of Lachman’s Test performed on an injured ACL knee. The compliant haptic interface was capable of displaying stiffnesses between 4200 N/m and 7200 N/m.

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.

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.

Design of a Continuum Mechanism that Matches the Movement of an Eight-bar Linkage

2020 ◽  
pp. 1-11
Author(s):  
Xueao Liu ◽  
J. Michael McCarthy
Keyword(s):  
Finite Element Analysis ◽  
Rigid Body ◽  
Design Methodology ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Initial Structure ◽  
Element Analysis ◽  
Kinematic Synthesis ◽  
Generic Structure ◽  
Straight Line

Abstract This paper presents a design methodology for mechanisms consisting of a single continuous structure, continuum mechanisms, that blends the kinematic synthesis of rigid-body mechanisms with topology optimization for compliant mechanisms. Rather than start with a generic structure that is shaped to achieve a required force deflection task for a compliant mechanism, our approach shapes the initial structure based on kinematic synthesis of a rigid body mechanism for the required movement, then the structure is shaped using Finite Element Analysis to achieve the required force deflection relationship. The result of this approach is a continuum mechanism with the same workpiece movement as the rigid link mechanism when actuated. An example illustrates the design process to obtain an eight-bar linkage that guides its workpiece in straight-line rectilinear movement. We show that the resulting continuum mechanism provides the desired rectilinear movement. A 210 mm physical model machined from Nylon-6 is shown to achieve 21.5mm rectilinear movement with no perceived deviation from a straight-line.

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.

Large Deformation Analysis and Experiments With Double Parallelogram Compliant Mechanisms

2018 ◽  
Author(s):  
Abhijit A. Tanksale ◽  
Prasanna S. Gandhi
Keyword(s):  
Large Deformation ◽  
High Precision ◽  
Large Deformations ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Vertical Plane ◽  
Coupled Analysis ◽  
Deformation Analysis ◽  
Flexible Beams ◽  
Straight Line

Compliant mechanisms are highly preferred in applications demanding motion with high precision. These mechanisms provide friction-less, backlash-free precise motion obtained through deformation of flexible members. The double parallelogram compliant mechanism (DPCM) is one the most important compliant mechanisms to obtain highly precise straight-line motion. DPCM when operated in horizontal plane yield high precision straight-line motion (even with large deformations) useful in several engineering applications. However, constraints such as space, dead loads, etc. may demand DPCMs to be used in the vertical plane. For DPCMs operating in a vertical plane, the axial load due to gravity causes tension and compression in flexible beams which get coupled to bending under large deformations. This ultimately affects the parasitic error of straight-line motion. This paper presents a coupled analysis, along with experimental validation, of DPCM operating in vertical plane considering gravity effects with large deformation.

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