nsf engineering research center for reconfigurable machining systems reconfigurable manufacturing...

NSF Engineering Research Center for

Reconfigurable MachiningSystems

Reconfigurable Manufacturing Systems

A. Galip Ulsoy, Center Deputy DirectorWilliam Clay Ford Professor of Manufacturing

University of Michigan, College of EngineeringApril 11, 2002

NSF Engineering Research Center for Reconfigurable Machining SystemsUniversity of Michigan College of Engineering

RMS Seminar # 2

Outline

• Reconfigurable Manufacturing Systems (RMS)– Basic concepts– ERC/RMS research plan

• Capacity Management Policies• Combined Design and Control• Concluding Remarks


RMS Seminar # 3

Develop Product A

Design & BuildManufacturing System

Product Ain-market

Ramp-Up

Concept

Produce A for 10 - 20 years

Economic Goal: Shorten System

Design & Reconfiguration Lead-TimeP

rese

nt

Product design timereduced by CAD

System Lead Time

Exactly the functionality needed… … Exactly when needed

Develop Product B

Develop Product C

Reconfiguration

Produce A & B

Produce B & C

RU RUProduce A

Develop Product A

Time

Design & BuildManufacturing

System

Product Ain-market

RampUp

GOAL


RMS Seminar # 4

Comparison of Three Types of Systems:

Capacity & Functionality

Functionality

Ca

pac

ity

ProductA

DedicatedMfg. Line

MultipleProducts

ProductB + C

Exactly the functionality and capacity needed . . .. . . Exactly when needed.

F M S

ProductA + B

R M S

R M S

R M S

A

A + B

B + C


RMS Seminar # 5

Reconfiguration Scenario400,000

300,000

0 3 6 8

Actual

Projection A

Product A

Year

Product B

Product A; 300,000 parts/year

Year 0

A A


B

Line 2

Line 1A & BYears 3&6

A

Product A or B; 200,000 parts/year

Line 2

Line 1Year 8A

B

LaserStn.

A & B


Product A or B; 250,000 parts/year


RMS Seminar # 6

Optical Measurement for Quick Ramp-Up


RMS Seminar # 7

Rapid ramp-up is critical for successful reconfiguration,but it’s also useful for traditional systems

6 [mm]

8.0without SoV

(Data from a real plant)

6.0

4.0

2.0

12 24 36

10.0

with SoV

Installation Time [weeks]48

Ramp-Up Methodology

New methodology for systematic ramp-up of large systems based on stream-of-variation theory (SoV)

• Utilizes state-space modeling combined with statistical analysis methods

• Needs high-speed high-accuracy measurement


RMS Seminar # 8

Reconfigurable?

DedicatedFlexible

Reconfigurable

• Reconfigurablity concept - wrenches

• RMS: reconfigure capacity and functionality

• Reconfigurable vs dedicated vs flexible is an economic decision


RMS Seminar # 9

RMS Science Base

A set of theories and laws that are applicable to the synthesis and analysis of RMSs

and share key characteristics

RMS Science Base

Controllerconfigurationmethodology

Reconfigurablemachine

design theory

Networked Control

Stream-of-variation theorySystem

configuration rules f(machine reliability,

quality,…)

Life-cycle economicModeling

RMT machine diagnosis &calibration

Convertibility

Customization

Integrability Diagnosability

Modularity Scalability


RMS Seminar # 10

Major Research Issues in RMS

Part Family

Market Demand:Volume & Mix

ReconfigurableSystemDesign

CoP 1System-Level

Design

Library ofMachine

Modules &MachinesReconfigurable

Machinesand Controls

CoP 2Machine / Control-Level Design

Ramp-Up Methodology

CoP 3Calibration and Ramp-Up


RMS Seminar # 11

Center Projects

RMSDesign

RMSRamp-Up

ReconfigurableMachines

Part FamilyMarket ChangesVolume & Mix

S2Scalability& MaterialHandling

S1System-LevelConfigurator

& Process Plan

M1ReconfigurableMachine Design

Methodology

M4Network-Based

Control

R2Reconfigurable

ProcessMonitoring

S3System

ConfigurationImpact

M3Modular Logic

Control

M2&M5SpindlesFor RMTs

R4Machine Vision

R1Stream-of-Variations

For SystemDiagnostics

S4Life-CycleEconomicModeling

R3Rapid OpticalMeasurement

of Parts

CoP 3CoP 2CoP 1

Exploratory Projects

Testbed Projects for proof-of-concept and integration


RMS Seminar # 12

Center Testbed Facility

A brief (1.5 minute) video presentation. Also an ERC Testbed web cam is available live at

http://erc.engin.umich.edu/webcam.htm


RMS Seminar # 13

Delphi study involving experts from around the world:

•Reconfigurable Manufacturing Systems identified as one of six grand challenges

•Adaptable and reconfigurable systems - priority technology number 1

•http://www.nap.edu/readingroom/books/visionary/

National Research Council: Visionary Manufacturing Challenges for 2020

The impact of the ERC/RMS, in just 5 years, has been worldwide

RMS featured in CIRP 99 keynote paper, JUSFA 00 and JIMTOF 00 keynote papers, ASME conferences/publications, 1st CIRP RMS conference 01 and Feb. 02 issue of ASME ME magazine.


RMS Seminar # 14

Outline

• Reconfigurable Manufacturing Systems (RMS)• Capacity Management Policies

– Capacity management via feedback

• Combined Design and Control• Concluding Remarks


RMS Seminar # 15

How much?How much?

Capacity Management:

Motivation

Time

• A Reconfiguration Decision Consists of Two Parts:– When?– How Much?

Capacity

Market Demand

When?


RMS Seminar # 16

Capacity Management ProblemOptimize Cost Function Wi(Ci, Di, yi) w.r.t:

Time

X][

},min{

1 XTiii

iii

XCC

DCy

−+ +==


RMS Seminar # 17

Capacity Management Problem

Time

Capacity &

Market Demand Demand

(Slope=d)

• What has been done?– Capacity Management Policy– Uniform capacity expansion [Manne, 1961 & 1967]

Expansion Size (x)

€

x ≈2Ad

Br

Δt ≈2A

Bdr

Optimal Solutions:


RMS Seminar # 18

Capacity Management - Background

Cost Function:

∑∞

=

−+=

0

)(n

d

nxr

eBxAW

Fixed Cost Variable CostExpansion Size

Discount Rate

Demand Slope

Expansion Size (x)

Cost (W) Optimum Value


RMS Seminar # 19

Manne’s Example: Optimal Results


RMS Seminar # 20

Manne’s Example: Results• What are the issues?

– Slope might change– Discount factor might change

• In addition to minimum cost, we need to consider sensitivity and robustness


RMS Seminar # 21

Capacity Management via Feedback

i i


RMS Seminar # 22

Manne’s Example: Feedback Approach

i i

Controller Design

C(t)

€

[D(t) −C(t)]dt = iα0

ti∫

α =A

Br⇒ Δt =

2A

Bdr


RMS Seminar # 23

Manne’s Example: Results w/ Feedback


RMS Seminar # 24

Manne’s Example: Results w/ Feedback


RMS Seminar # 25

Stochastic Demand Example

Stochastic Market Demand [Freidenfelds, 1980 & 1981]


RMS Seminar # 26

Stochastic Demand Example: ResultsStochastic Market Demand [Freidenfelds, 1980 & 1981]

Mean and variance of cost are both reduced using the feedback approach


RMS Seminar # 27

Capacity Management: Optimal Policies

• Numerical Example and Results (A=R=0)


RMS Seminar # 28

1. New Design 2. Change3. Respond4. Quick5. Time Delay

Introduce Dynamics In The Problem

Time

Capacity &

Market Demand


Effect of Delay


RMS Seminar # 29


Problems Due to Delay


RMS Seminar # 30


Optimal Policy Which Accounts for Delay


RMS Seminar # 31

Outline

• Reconfigurable Manufacturing Systems (RMS)• Capacity Management Policies• Combined Design and Control

– Combined optimality conditions and coupling

• Concluding Remarks


RMS Seminar # 32

Plant/Controller Optimization Strategies

Optimize the plant

Optimize the controller

Optimize the system by varying both plant & control

Optimize the plant without compromising control

performance


Optimize the system by varying the plant

Sequential

Iterative

Simultaneous

Nested



RMS Seminar # 33

Sequential vs. Simultaneous Strategies• Definitions

• Theorem 1: The plant and controller optimization problems are coupled in the sense that their sequential solution does not necessarily give a combined optimum.

Vector of plant design variablesVector of controller design variables

Combined objective functionSet of feasible plant/controller designs


RMS Seminar # 34

Combined Plant/LQR Control Optimization

⎪⎭

⎪⎬

⎫

⎪⎩

⎪⎨

⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛+

+

∫T

tc

p

t

o

dttttLTTw

ew

)),(),(()),((

)(

min)(, uxx

d

ud φ

:.tos 0dh =)(

0dg ≤)(

),),(),(()( duxfx tttt =•

0du ≤),),(( ttη

0x =)),(( TTψoot xx =)(


RMS Seminar # 35

Combined Optimality Conditions

0dh =)(0dg ≤)(

0d =Tβ

0≥β

βα TTe ddd gh0 ++= ( )T

T

tp

c

o

dtw

w⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+− ∫ μηλ ddf

0du ≤),),(( ttη),),(),(()( duxfx tttt =

•oot xx =)(

0x =)),(( TTψ

( )( ) 0

xxx

=⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

−++

−++

)(Td

dTfL

T

T

T

TTtt

λνψφ

λνψφ

0=ημT

0H uu =− μηT

0≥μ

⎪⎭

⎪⎬

⎫

⎪⎩

⎪⎨

⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛+

+

∫T

tc

p

t

o

dttttLTTw

ew

)),(),(()),((

)(

min)(, uxx

d

ud φ

:.tos 0dh =)(0dg ≤)(

),),(),(()( duxfx tttt =•

0du ≤),),(( ttη

0x =)),(( TTψoot xx =)(


RMS Seminar # 36

The Coupling Term/Decoupling Cond.s

• The coupling term:

• Sufficient decoupling conditions:– Pareto limit condition (special case of boundary decoupling).– Zero coupling term condition (interior decoupling).

• Necessary decoupling condition (interior & boundary decoupling):– When the contribution of the optimal attainable control

performance to the system objective cannot be enhanced without violating active plant design constraints, the two problems decouple.

( )T

T

tp

c

o

dtw

w⎟⎟

⎠

⎞

⎜⎜

⎝

⎛+− ∫ μηλ ddf


RMS Seminar # 37

Summary and Conclusions• Reconfigurable Machining Systems (RMS)

– Can be (re)configured in response to market– Reduce lead time, including ramp up– Center research organization

• Capacity Management Policies– Capacity management problem– Optimal robust capacity reconfiguration policy based on feedback– Results (deterministic & stochastic) and effect of delay

• Combined Design of Plant and Controller– Sequential, iterative, nested and simultaneous strategies– Coupled problem formulated and existence of coupling proven– Optimality conditions and coupling


RMS Seminar # 38

Acknowledgements and References• Acknowledgements

– Collaborators: Farshid Asl, Hosam Fathy, Yoram Koren, Panos Papalambros

– Sponsor: NSF Grant EEC 9529125

• References– RMS:

• Koren et al, CIRP Keynote Paper 1999

– Dynamic Modeling of RMS: • Asl, Ulsoy and Koren, JUSFA 2000

• Asl, Ulsoy, ACC 2000, JUSFA 2002 & IMECE 2002

– Combined Design and Control:• Fathy, Papalambros and Ulsoy, ACC 2001 & DET 2001

nsf engineering research center for reconfigurable machining systems reconfigurable manufacturing...

Documents

b product

partsyear product

b b c slide

product c reconfiguration

partsyear b line

types of systems

large systems

traditional systems