Supervisor

Dimiter Zlatanov, University of Genoa Sebastien Briot, Ecole Centrale de Nantes

By Vishal Ramadoss

Conceptual Design of 3-DOF

Deployable Mechanism

2

● Introduction

Motivation and Needs

Deployable Mechanism Units

Existing Models

● Proposed Mechanism

Statics Analysis

Singularity Analysis

• Simulation and Validation of Model

• Conclusion

• Bibliography

Index

3

● Deployable : To arrange in a position and to move

strategically.

● Mechanism : Rigid bodies connected by joints to

accomplish a motion.

● Degree of Freedom(DOF):number of independent

parameters that define its configuration.

● Conceptual Design: The very first phase of design in

which drawings and models are created.

Motivations

4

● Deployable structures can change shape so as to

significantly change its size

● Applications are for deploying solar panels/sails in

aircrafts , antennas , dome structures , portable shelters.

Deployable Mechanism Units

Example of Deployable Cube . Image courtesy : Universite Laval

5

● The basic linkages are Bennett (Four Bar), Myard

(Five bar) , Bricard (Six Bar) , Scissor , Sarrus,

Hoekens and few more .

● The degree of freedom of the deployable

mechanism must be greater than 1 and less than 4 ,

3-dof is a suitable choice .

● Modeling and simulations of various existing

linkages to familiarize the tools and mechanisms.

Existing Models

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● A set of deployable mechanisms, which have two

degrees of freedom obtained by linking multiple

deployable units, each of which is composed of four

scissor and two Sarrus linkages.

Existing Models

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Chain of Research Method to

Application

Deployable Mechanism

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Prototyping

Research Methodology

• My work is the first step in the development chain and conceptual design lays the foundation for an efficient

working mechanism .

Conceptual Design

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● The original effort goes into drawing and modeling the

mechanism using 3D software (Creo/Solidworks) with

different possibilities of linkages to design a new

mechanism.

● Tiling up several set of linkages in triangular/ rectangular or

different patterns .

● The mechanism should also be made to approximate

certain curves, e.g. an ellipse/a hyperbola or parabola. In

three dimensional surfaces , ellipsoid , hyperboloid and

paraboloid

Original Effort

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Development of Experiments and

Validation

CAD models of 2-dof and 3-dof deployable mechanism with elliptical And hyperbolic outline.

● Selection of basic unit for the mechanism . ● The unit mechanism can be assembled to form the desired shape while satisfying all geometric constraints ● Position , Velocity, Statics and Singularity analysis . ● Modeling in CAD software ● Addition of new unit will not increase the degree of freedom.

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● The tiling up of several units is a major challenge as we do

not know whether the triangular / parallelogram pattern is

efficient . So we have to try out different choices and with

different basic linkages.

● The Degree of freedom must be greater than1 for practical

applications as already extensive research has been done in

1-dof mechanisms and 2-dof mechanism.

● The deployed form must approximate a surface .

● Link interference poses a major challenge .

Challenges

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The 2-dof Model • The device, with two decoupled dof, is able to control its elliptical boundary by varying independently the two parameters in the standard ellipse equation

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The 2-dof Model

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● Tiling up 2-dof mechanism with set of links in z- direction to

form an ellipsoid mechanism which has 3-dof.

Proposed Model

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● Tiling up 2-dof mechanism with set of links in z- direction to

form an ellipsoid mechanism which has 3-dof.

Proposed Model

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● Four view viewport

Proposed Model

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● Four view viewport

Link interference

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● Interference when the mechanism contracts .

Link interference

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● Adding different layers of ellipses with different sizes such that it

approximates an ellipsoid surface .

● To be able to drive in 3

Decoupled directions.

● Link interference has to be

eliminated .

● Static analysis should be

performed.

Work to be done

19

● Chen, Y.: Design of structural mechanism. PhD Thesis,

University of Oxford, Oxofrd (2003).

● Lu, S. N., Zlatanov, D., Ding, X. L., Molifino, R., and Zoppi, M.,

2013. “A novel deployable mechanism with two decoupled

degrees of freedom”. ASME IDETC/CIE 2013,p. 13187.

● Lu, S. N., Zlatanov, D., Ding, X. L., Molifino, R., and Zoppi, M.,

2014. “Approximation and control of curvilinear shapes via

deployable mechanisms with two degrees of freedom”ASME

IDETC/CIE 2014,p. 35411.

● Lu, S. N., Zlatanov, D., Ding, X. L., Molifino, R., and Zoppi,

M.2014,”Mechanisms with decoupled freedoms assembled from

spatial deployable units”

Bibliography