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Ananthasuresh, IISc, Dec. 2013

G.K. AnanthasureshandAll the current and past members of the M2D2 LaboratoryMechanical EngineeringIndian Institute of ScienceBangalore

Motion without Hinges and Sliders

1


G.K. AnanthasureshandAll the current and past members of the M2D2 LaboratoryMechanical EngineeringIndian Institute of ScienceBangalore

Mobility, Analysis, and Synthesis

2

Compliant mechanisms

Rigid-body mechanisms

Equivalent compliant mechanism

Int. J. Solids and Structures44(2007), pp. 6279-6298With Jiten Patel

CompliantMechanism.MOV


Smooth transition

Rigid closed chain

Rigid serial chain

Elastic chain

BRUcoffeeJar.wmv


Kinematic pairs

Rigid bodies

Elastic segments

Elastic pairs

rigid chains

elastic chains


Kinematic pairs

• Lower pairs with surface contact

– Revolute (hinge-1 dof)• Surface of revolution

– Prismatic (slider-1 dof)• Prismatic surface

– Helical (screw-1 dof)

– Cylindrical (2 dof)

– Toroidal (2 dof)

– Spherical (ball-socket-3 dof)

– Planar (3 dof)

• And there are many, many higher pairs with line or point contact

Specific shapes

for contact

surfaces


Elastic pairsNo specific

shape

Elastic 1-dof rotational pairs

Elastic 1-dof sliding pairs

Elastic 2-dof rotational pairs

WithAshwin RaoSantosh Bhargav


1-dof rotational

elastic pairs

More than a dozen shapes for 1-dof elastic rotational pairs!

Bendix elastic rotational pair

BendixElasticPair.wmv


Shapes of elastic pairs can be quite complicated.

You can even call them compliant mechanisms in their own right!

With Dinesh Mana

Awtar, 2003


Distinguishing pairs quantitatively

Kinematic

• Ideally…– Zero stiffness along

or about the intended axis.

– Infinite stiffness along or about all other five axes.

– Almost no cross-axis errors.

• Friction and backlash cause deviation from the ideal condition.

Elastic

• Ideally and realistically…– Finite but low stiffness along or

about the intended axis.

– Finitely large stiffness along or about all other five axes.

– Finite cross-axis errors

• Friction and backlash are absent.

• Viscoelastic behavior may cause deviations.

• Axis may drift.


Multi-axis stiffness of an elastic pair

xx xy xz x x x

yy yz y y y

zz z z z

xx

yy

zz

x

y

z

k k k k k k

k k k k k

k k k k

k k k

k

Fu

F

Fu

M

k

u

k

M

M

Ku f

Elastic deformation analysis, analytical or numerical, via the compliance matrix can be used to compute K.


Computing the multi-axis compliance matrix

1

xx xy xz x x x x x

y yyy

z z

x

y

yz y y y

zz z

z

z z

c c c c c c

c c c c c

c c c c

c c c

c c

F u

F u

F u

M

c

M

M

K C

Up to six analysis runs…Three finite element analysis runs in 2D.Six finite element analysis runs in 3D.


No joints (pairs) at all

AnchoredForce

Displacement

A compliant mechanism with elastic segments

Distributed complianceNo elastic pairs.Uniformly distributed deformation.Large displacement with small strain.Stronger than elastic pairs.Enhanced scope for design.

Elastic segments instead of elastic pairs.

GripperVideo.AVI


Compliant Mechanism: the definition

• A mechanism that uses elastic deformation to transmit or transform force, motion, and energy.

Replace many parts with one part.


Transmission is fine;transformation?

Change

• Amplify force or motion

• Change direction

• Change the dynamics

• Change state

Transduce

• Convert non-mechanical energy into mechanical energy and vice versa.

• Smart or active materials

With Moulton

WithAnupam Saxena and LuzhongYin

AmplifyMotion.AVI

ChangeDirection.AVI

ETCactuator.mpg


And then there is semantics!

Compliant

Accommodating

Acquiescent

Agreeable

Amenable

Complaisant

Non-resistant

Obedient

Obliging

Yielding

…

Deformable

Elastic

Flexible

Lithe

Limber

Lissome

Pliable

Pliant

Supple

…

Two connotations and one concept


A picture is worth 1000 words!

Steven Vogel, Discover, May 1995

Tension leg platform

Compliant offshore structuresBar-Avi and Benaroya, 1998

Being compliant and strong is an equally, if not more, attractive alternative to beingstiff and strong.

Platform

Pontoon

Co

lum

n


The importance of being compliant

http://www.fao.org/docrep/006/x8234e/x8234e08.htm

How wheat plants avoid “lodging” by being compliant.

Struct Multidisc

Optm’n (2009)

39:327–336

WithP. Sivanagenrda

http://www.fao.org/docrep/006/x8234e/x8234e08.htm


Monolithic (uni-body; single-piece) construction

• Ease of manufacture – reduced or no assembly

Ananthasuresh and Saggere, 1994

Elastic pairElastic segment


Tune your stiffness as needed.

By adding intermittent contacts, stiffness can be changed.

We call them contact-aided compliant mechanisms.

WithNilesh Mankame


Tuning stiffness…

Gripper + bistable mechanism =>

Stiffness reduction + discerning specimen’s stiffness

F

uout

Soft gripper

with negative stiffness

WithSantosh Bhargav and Gaurav Singh

SoftGripper.avi


One inside the other…multi-scale graspers

WithNandan Maheswari


Stiffness matched to that of the biological cells

Force estimated to deform the zerbafish embryo by 150 µm is

1.2 mN. Thus the bulk stiffness is about 8 N/m

All dimensions are in mm

10

10

1.7

0.7

Pockets

Zebrafish egg squeezing

Zebrafish egg rolling

Too soft for drosophila embryoMCF-7 cell grasping

WithSantosh Bhargav

zebrafish_embryo.wmv

ZebrafishSqueeze.MPG

ZebrafishEggCell_rolling.avi

8_Grasping_Drosophila_embryo.wmv

10_Grasping_MCF7_cell.wmv


Tuning stiffness… by combining

Gripper + DaCM =>

Stiffness tuning + GA

Contact

points

Pulling

mechanism

Compliant

clamp

Suspension

beams

Stretch too…

WithSantosh Bhargav

StretchMechanism.wmv


Composite compliant mechanisms

FaCM + DaCM => MA + GA

Crush cement blocks and measure breaking force.

WithSantosh Bhargav

14_breaking_cement_sample.wmv


Don’t they break?

But flexibility does not imply the lack of strength.

And, rigidity does not imply strength either!


• Ability to withstand overloads –“I bend but I break not.”

Yes, they do…like all others that are not designed well.

It is a question of choosing the right material and having a suitable design.


Flexibility and shape

Cut a spiral in an acrylic sheet and pull up the centre. This shows that flexibility is a matter of design.


No more rubbing the wrong way

Input force

Output motion



• Less or no friction and wear

• No backlash problem – more precision

Prefer hinges to sliders,flexures to either.- M. J. French


Is compliant design difficult?

• Some people think so. It may be because…

– you need to deal with elastic deformation.

– you need to deal with elastic pairs and elastic segments as opposed to discrete rigid bodies.

• It is in fact easy once we pay attention to…

– what benefits we can achieve with deformation

– deformation mechanics in addition to kinematics


Is compliant design new? No, it isn’t.

We find them all around in simple products.

Nature has been using them for a long time!

An ancient compliant mechanism


One-piece clothes peg holds clothes in gales!

Imagine a clothes peg which:. Is a single moulded item. Has no metal parts to rust. No wood to stain clothes. Will not break, made of polypropylene. Grips your clothes even in gales

This BRITISH product which is UNIQUE in design has a POWERFUL integral spring action. Being made in 100% PLASTIC they are totally RUST FREE

Up to 3 times stronger than metal sprung pegs.From the product description…

ClothesPinVideo.AVI


Aesthetics made easier.

From www.compliersinc.com

Prof. Ashok MidhaMissouri University of Science and Technology

Compliers, a fish-hook remover





• Aesthetics made easier


Which one will you buy?

Audrey

Preo

Tweezerman

Beautyimpex


Real applications• Ease of manufacture – reduced or

no assembly





• Economy of material and less cost for better performance

Prof. Larry HowellBrigham Young University

Over-running and one-way clutches

Gahring and Ananthasuresh


Mission-adaptive compliant wings

Prof. Sridhar Kota, University of Michigan


Currently under further development by Endovalve, Inc., USA

Patent

“Percutaneous Heart Valve,” Patent application #.

PCT/US2004/023211 dated 20th July, 2004 (H.C. Hermann and

N. Mankame, G.K. Ananthasuresh)

An artificial heart valve

EndoValve 09-16-08.wmv


Improved micromachined accelerometers

WithSambuddha Khan


External pipe-crawler

A compact ring-actuator

Inchworm concept

WithPuneet Singh et al.

RingActuatorCrawler.MPG

CrawlerConcept.avi


Micron: a force sensor

Output

Input

Deformation analysis

Evaluation: effective stiffness of 26.N/m or

2.6uN /um

~2 mN resolution~ 1 mN range

Baichapur, Bhargav, Gulati, Maheswari, and Ananthasureh, 2012

GauthamMicroN_WMV V9.wmv


These are good wheels!

Tweel from Michelin.Non-pneumatic tire from IISc.

ME project report, G. Bhargav, 2008.


Almost any type of motion

• Displacement amplification

• Curved paths

• Non-smooth paths

• Frequency tuning

• Constant-force

• Actuator characteristic modification

• Etc.







• Any type of motion


Non-smooth curved pathsMankame, N. and Ananthasuresh,

G.K., Journal of Mechanical Design. 126(4), 2004, pp. 667-672.

Mankame, N. D. and Ananthasuresh, G. K., International Journal of Numerical Methods in Engineering, 69 (12), 2007, pp. 2564-2605.

Movie

ccm1trim.mpg


Actuator characteristic modification

Pedersen, C. B. W., Fleck, N. A. and Ananthasuresh, G. K., Journal of Mechanical Design, 128(5), 2006, pp. 1101-1112.


Signal processing−band-pass filter


Micromechaical signal processors

• Band-pass filters

• Switches and relays

• Amplifiers

• Frequency-translators

• Clocks

Output side

input side

WithSambuddha Khan and Nirmit Dave


Size no bar!• Ease of manufacture – reduced or

no assembly







• Suitable for any size

Micromachined accelerometer

MicroDaCMaccelerometer.avi


Miniature grippers

Proteins are deformable structures.

They are nano-compliant mechanisms found in biological matter.

Flexible motions—conformational changes—endow functionality to most proteins.

Myosin (1DFL)

Hemoglobin

Lactoferrin (1LFG)

http://www.andrew.cmu.edu/user/jl2p/Hb_html/dimers.html

G. Chirikjian, Johns Hopkins University


3D too…


Small CMs with steel

Shishira Nagesh, summer intern from NIT-Surathkal


Miniature metal gripper

Fourth stage on spark erosionTop view

of the punch

Punched out of spring steel sheet.

Journal of Manufacturing Processes 15 (2013) 108–114With Rakesh Pathk and Ravi Kumar

MetalGripper.wmv


Meta-materials• Ease of manufacture – reduced or

no assembly







• Suitable for any size

• Amenable for non-mechanical actuation

• Material microstructure design

(Almgren, 1982)

(Made by Hsu using MIT’s wafer bonding, 1996)


Negative thermal expansion coefficient

(Sigmund, Denmark Technical University)


Are there any disadvantages to compliant mechanisms?


Efficiency and mechanical advantage compromised!

2 2

in outin in out out

in in out out

out out in in

out in

in out in out

r c

F FW F F

F F

SE

F F SE

F SE

F F

MA MA MA

More about it in a paper

(Salamon and Midha, 1998)


Static balancing: why?

Professor Just Herder, Delft University, The Netherlands


Static balancing of a compliant mechanism

With Amrit Hansogi and Sanagemsh Deepak


High speed motion

• Too many cycles

• Too low a frequency

• Nonlinear inertial effects

• Parametric resonance

• Viscoelastic effects


Optimum design for distributedcompliance is still elusive… somewhat

Discrete compliance Distributed compliance

Synthesized topologies

With Luzhong Yin


Prefer hinges to sliders,flexures to either.

Prefer hinges to sliders,flexures to either,distributed compliance to all.

M. J. French


Compliant utopia

• Distributed compliance

– Geometry Uniform geometry.

– Kinematics Equal deformation.

– Stress Evenly stressed.

• Helical spring is a good candidate.


Multi-disciplinary and Multi-scale Device and Design Lab


Look, Sci-Walker with compliant legs!

Pulkit Kapur, summer intern in IISc.


PhD studentsA Narayana Reddy

Sourav Rakshit Sudarshan Hegde

Sangamesh Deepak RSambuddha KhanSantosh Bhargav

Sudhanshu SekharKiran AkellaBiplab Sarkar

T. J. Ramnath BabuNandhini Nehru

Shantanu ChakravarthyAnasuya DigheG. vasundhara

Sreenath BalakrishnanM. S. Suma

Administrative AssistantsT. S. DeepaT. Bharath K. Bindhu

Faculty CollaboratorsAshitava Goshal (ME)H.S.Jamdagni (CEDT)Navakanta Bhat (ECE)

Saraswathi Vishveshwara(MBU)

K.J.Vinoy (ECE)Saumitra Das (MRDG)

G. Mohan Rao (ISU)C. S. Jog (ME)

Utpal Nath (MCB)

Multi-disciplinary and Multi-scale Device and Design Lab

SponsorsDST, BRNS,

NPOL, ADA,

NPSM, DRDO, ISRO, SBMT,

NPMASS, and

industries.

Thank you!

Project staffG. Balaji, Shantanu

Chakravarthy, B. Manjunath, M. S. .

Deepika, B. K. Deepthi, P. Dinesh, B. Pradeep, A.

Singh, A. Alwan, M. Kulkarni, R. Ganesh, K. Girish, Siddharth Sanan,

K. Manjunath, Vinod Kumar, Vedanandan, A. Ravi Kumar, Manoj Raj,

Chetan Kumar, G. Ramu, Duely Rakshit, Vijay Prakash, G. Ramu, A. Sajeesh Kumar, M. S.

Suma, Meenakshi Sundaram, Vishwaman Malaviya, R. Genesh,

Krishna Pavan, B. Varun, Mukund Madhav Nath,

Puneet Singh, Shilpa, Ashwin Rao, Gaurah

Singh, Gautham Kumar, Gautham Baichapur,

Nikhil Jorapur, Avinash Kumar, Kunal Patil.

Masters studentsGirish KrishnanV. S. S. Srinivas

M. DineshShyam Madhavan

Harish VarmaJagdish SinghSaurabh Mitta

Saurav RakshitP. Sivanagendra

Manish AgrawalM. Rajesh

Deepak SahuG. Bhargav

P. Mallikarjuna RaoPadmanabh Limaye

Meenakshi SundaramPakeeruraju Podugu

Subhajit BenerjeeNirmit DaveGaurav Nair

Rakesh PathakNavaneet Krishna

P. SandeepMohit Mathur

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