" '<'-" ;*,.,.

CONTRACT NO. NAS 5-25182P.O. 167-HA 3463

9 JULY 1984TASK ASSIGNMENT NR 740-9

- FINAL REPORT -

SPACE STATION AUTOMATION STUDY

AUTOMATION REQUIREMENTS DERIVED FROMSPACE MANUFACTURING CONCEPTS

(NASA-CB-177862-Vcl-l) SPACE STATION N86-27399AUTOMATION STUDY:' AUTCMAIICN EEQUIBEMENTSDERIVED FEOM SPACE MANUFACTUEING CONCEPTS. ,VOLUME 1: EXECUTIVE SUMMABY Final Report Unclas

Co. ) 34 p_EC A03/MF A P I . 63/18 .4.3115

VOLUME IEXECUTIVE SUMMARY

SPACE SYSTEMS DIVISION

Valley Forge Space CenterP.O. Box 8555 Philadelphia, PA 19101

G E N E R A L ®ELECTRIC

CONTENTS

1.0 Introduction 1

2.0 Study Objectives, Guidelines and Approach 6

3.0 Study Results 8

3.1 GaAs Electroepitaxial Crystal Production 9

and Wafer Manufacturing Facility Description

3.2 Crystal Production and Wafer Manufacturing 13

Facility Automation Requirements

3.3 Microelectronics Chip Processing Facility 16

Description

3.4 GaAs Microelectronics Chip Processing 21

Facility Automation Requirements

4.0 Conclusions 24

5.0 Recommendations 29

1.0 INTRODUCTION

The purpose of the Space Station Automation Study is

to develop informed technical guidance to NASA in the use

of autonomy and autonomous systems to implement space

station functions.

The study organization is shown in Figure 1.0-1.

NASA headquarters formed and convened a panel of recognized

expert technologists in Automation, Space Science and

Aerospace Engineering. CAL SPACE was assigned the

responsibility for study management, and for convening and

directing a University/Industry Committee to produce the

Space Station Automation Plan. A Senior Technical

Committee, chaired by Dr. Robert Frosch, was appointed to

provide top level technical guidance.

STUDY DIRECTIONNASA HDQTRS

D. HERMANV. ANSELMO

1

STUDY MANAGEMENTCAL SPACE

J. ARNOLD

\

UNIVERSITY/INDUSTRYCOMMITTEE

SENIOR TECHNICAL^ COMMITTEE

DR. FROSCH,CHAIRMAN

NASA_^ AUTOMATION _ EVALUATION

PLAN GROUPA.COHEN

1

• » SUPPORTING STUDIES

TECHNOLOGY ?ffSDESIGN [ TRW - SERVICINGTEAM TEAM 1 HAC - CREW PRODUCTIVITYSRI , ._,.._, . < MMC- CONSTRUCTIONH LUM L.POWELL GE - MANUFACTURING

R. HOOK | BAC-MAN.MArHINP

T f

1 1

COMPARATIVEASSESSMENT

1

LEVELS_. SPACE

STATION. N. HUTCHINSON

Figure 1.0-1. Space Station Automation Study Organization

-1-

SRI International was assigned to produce quality

focused technology forecasts supporting panel analyses and

guiding system concept design.

A NASA Design Team was convened to study the automation

of remote space operations to produce innovative,

technologically advanced automation concepts and system

designs which will strengthen NASA understanding of

practical autonomy and autonomous systems. Five Aerospace

Contractors, TRW, GE, HAG, MMC and BAG, were assigned to

this team.

The General Electric Company was assigned to assess

automation technology required for remote operations,

including manufacturing applications. In carrying out this

assignment, GE assessed over one hundred potential Space

Station missions through an extensive review of proposed

Space Station experiments and manufacturing concepts.

Subsequent meetings of the NASA Design Team resulted in the

direction to proceed with in-depth development of

automation requirements for two manufacturing design

concepts:

(1) Gallium Arsenide Electroepitaxial Crystal

Production and Wafer Manufacturing Facility

(2) Gallium Arsenide VLSI Microelectronics Chip

Processing Facility

Figure 1.0-2 provides a functional overview of the

ultimate design concept incorporating the two manufacturing

facilities on space station. For the purpose of this

study, the concepts were studied separately. This

separation allowed conclusions and results to be determined

in independent time frames without dependent cross ties.

-2-

GaAs CRYSTAL PRODUCTION ANDWAFER MANUFACTURING

FACILITY

.LABORATORYMODULE

(PRESSURIZED)

I I I fPROCESSING SUBSYSTEMS

J ITELEOPERATORS/ROBOTIC:

J I

ORS/ROBOTICS

ESSING SUBSYSTEPROCESSING SUBS'

I I

MICROELECTRONICS CHIP PROCESSINGFACILITY

Figure 1.0-2 Overview Of The GaAs Manufacturing

Facilities Concepts

Each facility would be developed in an evolutionary

step-by-step process. As they are developed, more and more

automation would be incorporated, evolving towards a full

automation, including maintenance, repair and refurbishment

functions.

Ultimately, in the year 2000 + time frame, it would be

logical that both facilities could be mated to a common,

standard space station pressurized laboratory module. The

part time crew would tend the two facilities from the

laboratory module, where all computer functions of process

control and data display would be performed, and quality

control checks and management of the finished products

accomplished. Either or both facilities could be operated

remotely from the Space Station, however, on separately

powered, unmanned free-flying or tethered platforms, with

control and data flow accomplished by RF communications

with the Space Station or with ground facilities.

Both manufacturing facilities would be contained in

enclosed structures as shown to help manage waste products

and contamination, and to facilitate man-tended repairs and

equipment upgrades.

-3-

, The electroepitaxial process grows crystals in a low

temperature furnace into ingots. These ingots, typically

three to five inches in diameter, are then sliced into very

thin wafers. The process provides defect free Gallium

Arsenide (GaAs) wafers when accomplished in a gravity-free

environment. In the second concept, many Very Large Scale

Integrated (VLSI) circuits (chips) are typically processed

on each wafer at the same time.

The two concepts were chosen for the main reason that

they both require a very, high degree of automation, and

therefore involve extensive use of teleoperators, robotics,

process mechanization, and artificial intelligence. They

cover both a raw material process and a sophisticated

multi-step process and are therefore highly representative

of the kinds of difficult operation, maintenance, and

repair challenges which can be expected for any type of

space manufacturing facility. The automation techniques

which would be developed for these space missions will

provide . direct benefits in the design of future

ground-based automated factories to be used for a wide

variety of materials processing and manufacturing

applications.

Supporting reasons for selecting the two concepts are:

(1) There is a growing demand for faster, larger, and

radiation hardened Integrated Circuits for which

. Gallium Arsenide has superior characteristics over

silicon.

(2.) An ultra-clean environment is necessary for

efficient electroepitaxial crystal growth (EGG)

and manufacturing of GaAs products. Additionally

EGG requires a microgravity environment. Onearth, EGG can only grow crystals of small size

and value because of gray.ity-induced convection

currents.

-4-

(3) The two concepts are compatible with each" other.

Although the Crystal Production/Wafer Manufacturing

Facility could probably be flown five years before the

Microelectronics Chip Processing Facility, eventually

the product of one would provide the wafers- to be

processed into chips by the other.

The study results, although specifically addressing crystal

growth and chip production, identify generic areas which will

require significant further study for any planned future

manufacturing in space. While cost analysis is beyond the scope

of this report, the economics and benefits of any space

manufacturing facility must be closely analyzed. The success of

Space Station will be determined to a large extent by the

programs ability to stimulate development of advanced

technologies and fully develop the commercial potential of space.

Advanced technologies for the automation of maintenance, repair,

and refurbishment activities, as well as contamination control

and waste removal represent major technological challenges to 'any

space based manufacturing facility. Advanced designs of space

manufacturing facilities will employ a high degree of automation,

however the initial designs will be based on state-of-the-art

hard automation such as terrestrial factories are employing and

will grow and evolve as space and terrestrial technologies

mature. > • '

The unique aspects of a space manufacturing facility compared

to a similar terrestrial factory, include the inability to bring

in technicians and specialists for maintenance and malfunction

repair. Therefore the advanced automation technology

requirements identified by the study are those systems required

to remotely monitor, diagnose, and automatically reconfigure,

maint'ain and repair in the event of malfunction. These

requirements embrace a broad spectrum of enabling technologies

ranging from ultimate expert systems for monitoring, diagnosis

and reconfiguration to teleoperation and robotic manipulative

systems to perform manufacturing, servicing and repair under

remote control from either the Space Station or ground.

-5-

c 2.0 STUDY OBJECTIVES, GUIDELINES AND APPROACH

The GE portion of the study was led by the Space

Systems Division, but also utilized the corporate

experience in manufacturing and automation in other GE

divisions. The GE work plan is shown in Figure 2.0-1.

TASKJ

REVIEW PREVIOUS STUDIES

TASK;

TASK REQUIREMENT SUMMARY

1

TASK 3

ADVANCED AUTOMATION ASSESSMENT

TASK 4

AUTOMATION PLAN

REVIEW SPACESTATIONMISSIONS

REVIEW AUTOMATIONLITERATURE. SPACE RELATED. TERRESTRIAL

-»•ASSESS ANDPRIORITIZEMISSIONS"

SELECTVIABLEMISSIONS FORFURTHER STUDY

'DEFINEGENERIC SPACEAUTOMATIONCONCEPTS

~^~*

DEFINE GENERICSUBTASKS

DETERMIN• BILITYOF

MATION C(FOR SUBT>

-»FOCUS ONTWO -HMANUFACTURINGMISSIONS

_ J

E AWL 1C AAUTO-JNCEPTSkSKS

DEVELOP BASELINE„ CONCEPT

• AUTOMATION• ROBOTICS• SENSORS• Al

*

DEVELOP AUTO-MATIONREQUIREMENTSFOR BASELINECONCEPT

GE CORPORATE.SUBCONTRACTOR. AVENDOR SUPPORT

SRI. GE CORPORATESUBCONTRACTOR &/ENDOR SUPPORT

REDIRECTEDORldlTOpr

ASSESSAUTOMATIONCONCEPTS CONCEPTS

&Ui~

DEVELOPAUTOMATIONPLAN ANDRECOMMENDATIOI

DEVELOPAUTOMATIONPLAN

Figure 2.0-1 GE Space Station Automation Study Work Plan

One hundred candidate missions published in the NASA

May 1984 Space Station Mission Requirements Report were

evaluated on the basis of automation potential and

availability of meaningful knowledge. Numerous reports

and technical papers presented in symposia and workshops

and as an outgrowth of funded studies were also reviewed.

As a result of this review the two concepts defined on page

2 were chosen for further development. In order to define

automation requirements for these concepts extensive

-6-

knowledge of the current manufacturing processes and

development of space based designs was necessary.

Data was provided by Microgravity Research Associates

(MRA) on the GaAs Electroepitaxial Crystal Growth (ECG)

experiment production unit planned for seven STS missions.

MRA assisted GE in developing a baseline concept for the

GaAs Crystal Production/Wafer Manufacturing Facility for

Space Station.

An in-depth analysis of GaAs microelectronics chip

production requirements was developed through evaluation of

GE Microelectronics Processing Facilities and work with Dr.

Keith Russell at the GE Microelectronics Center. The GE

Electronics Laboratory in Syracuse, NY was also evaluated

and provided data and background information on the GaAs

VLSI manufacturing process and the Molecular Beam Epitaxy

experimental laboratory.

Manufacturers of microelectronics processing equipment

were contacted and asked for support. VARIAN, APPLIED

MATERIALS, PERKIN-ELMER, EATON, GCA, ELECTROTECH and HARRIS

all provided valuable literature and information on the

design and operation of commercial processing equipment and

future products. VARIAN visited GE and assisted in the

conceptualization of space based processing equipment

designs. GE engineers visited three manufacturers, VARIAN,

PERKIN-ELMER, APPLIED MATERIALS, to obtain further insight

into process equipment technology for space application.

Design requirements and unconstrained design concepts

were developed for the two missions which consisted of

defined subsystems, facility layouts, and automation

schemes. These were presented at NASA Design Team meetings

and with helpful comments and direction from NASA, SRI, and

the CAL SPACE Automation and Robotics Panel members, a

finalization of the design concepts was undertaken.

— 7 —

3.0 STUDY RESULTS

The GaAs Crystal Production/Wafer Manufacturing

Facility concept requires a special furnace to provide for

crystal growth into ingots, and equipment for slicing and

polishing the wafers and placing them into cassettes within

containers. Extensive use of robotics and other automation

and mechanization techniques is required for handling of

the raw materials and waste, processing and handling of the

products, and test and servicing functions. The facility

would be highly automated, but man-tended for the purpose

of managing the processes and for maintenance; both ofs

these functions would evolve into nearly totally autonomous

operations through the use of automated servicing and

maintenance functions and control by use of artificial

intelligence concepts once they are fully developed and

proven in space.

The Microelectronics Chip Processing Facility consists

of seven subsystems which are based on latest

state-of-the-art and conceptualized commercial equipment

used for earth-based microelectronics processing. The

terrestrial versions of these subsystems are typically

stand-alone, separate pieces of equipment, sold by various

vendors. Current designs each provide their own computer,

software and handling devices. Wafer loading is usually

accomplished by people in clean rooms using standardized

cassettes each containing about 25 wafers. A vacuum

environment must be accomplished individually by each

subsystem during most steps of microelectronics processing.

Functions of each subsystem were studied and an

evolution into a space version developed. The vacuum

provided by space allows a major simplification of all

subsystems because the vacuum equipment associated with

each subsystem can be eliminated. The resulting ease of

equipment access also permits a very high degree of

-8-

automation. Instead of individual computers, a distributed

but integrated data management system is hypothesized, with

control and monitoring accomplished from the laboratory

module. Each facility could be either replaced entirely

with newer designs over the years, or be upgraded in space.

3.1 GaAs ELECTROEPITAXIAL CRYSTAL PRODUCTION AND WAFER

MANUFACTURING FACILITY DESCRIPTION

The conceptual design of this facility conforms to

design requirements which were developed as follows:

The projected demand for GaAs microelectronics of the

quality attainable in the space environment was defined.

The results are presented in Figure 3.1-1. Microgravity

Research Associates (MRA) provided the reference data for

this figure based on their own conservative marketing

research study. Because of the possibility for development

of other materials and/or processes, a saturation of demand

is conjectured. If, as MRA predicts, demand increases, a

second, upgraded system can be added.

MRAPREDICTION "

2.000

£ 1.000

100.000

50.000 F' 5

ti

20,000

90 92 94 96YEAR

2.000

ASSUMPTION

INITIAL AUTOMATEDFACILITY SHOULDPRODUCE 20.000WAFERSPER YEAR WITH GROWTHPOTENTIAL TO 80.000 W/YR

Figure 3.1-1. GaAs Projected Demand

-9-

The size of the furnace and size of the ingots to be

produced were determined by integrated analyses. An ingot

diameter of 3 inches was chosen primarily because furnace

power is proportional to area. Five inch diameter ingots

are expected to be the earth-based industry norm in the

near future, but require nearly three times the power

required for producing three inch ingots for the size

facility projected. This would be prohibitively high for

the IOC space station. Also, because GaAs is extremely

fragile, automated handling of three inch wafers will be

less risky.

Based on the 3 inch size ingot and the projected demand

curve, the furnace was sized to meet a startup capacity in

the 1995 time frame of 20,000 wafers/year at 26%

utilization, and require one third of available space

station power currently planned for the Initial Operational

Capability (IOC). Eventual growth to 95% capacity (near

continuous operation) would produce 80,000 wafers per

year: this would require roughly one third of the

projected space station power available by the year 2000,

and an optimization of the automation system into one which

is almost fully autonomous, including servicing and

maintenance functions.

A power recovery system for the furnace is incorporated

in the conceptual design. Further study would determine

more precisely how much net power would be required.

Analyses should also be accomplished to determine if a

separate power source would be warranted for each facility,

and to determine if other power reducing techniques (i.e.,

pulsed power) can be effectively employed.

A timeline study determined that each ingot should be

grown to a thickness which would yield three wafers per

-10-

ingot. This is because energy required increases with

ingot thickness, the source crystal can be better utilized

for this size growth, and adequate time is allowed for tray

refurbishment.

Figure 3.1-2 is a block diagram of the facility. It

defines the elements and automation processes required. A

conceptual design was ' accomplished for each element and

automation process, and packaged into a standard fourteen

foot diameter module, as shown in Figure 3.1-3.

FURNACESUBSYSTEM

Q»^ f ^+ 1

ENERGYRECOVERYSUBSYSTEM

nUNPRESSURIZED

PRESSURIZED

T =TRAYR = RECEIVERI = INGOT (=S+P)S "SEEDP =PRODUCTCj" CARRIER 1C2= CARRIER 2D = DOLLY

h-0-

Figure 3.1-2, Crystal Production And Wafer Manufacturing

Facility Block Diagram

-11-

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3.2 CRYSTAL PRODUCTION AND WAFER MANUFACTURING FACILITY

AUTOMATION REQUIREMENTS'-•• -• *'•" MtlZtoi• •••• --'-JO &003 ?,

The details of each element and automation process are

contained in Volume II. Automation requirements are

summarized in Figure 3.2-1.

Much of the automation is in the form of process

mechanization schemes similar to those used in factories

today for materials handling and manufacturing. However and

robots are conceptualized for servicing and maintenance

functions, primarily because of their flexibility. Their

operating profiles and timelines can be easily altered or

upgraded by software, and the configuration of end

effectors and their functions can be easily changed for the

required applications. In the concepts presented herein,

these teleoperators and robots are assigned the added task

of materials handling. if it were not for the challenges

of maintenance and repair presented by the limitations of

the space configuration, the materials handling could be

accomplished by straight-forward process mechanization as

in earth-based factories.

Artificial Intelligence (AI) will play an increasing

role in the operation of this facility, primarily in the

areas of process planning and control, and maintenance.

The complexities of electroepitaxial crystal growth, and

the sophistication of the furnace and slicing equipment

warrant an integrated "expert" . Expert process and

maintenance controllers offer an expanded knowledge-base to

aid Space Station crew members in identifying,

troubleshooting and handling anomalies in the crystal

growth process and associated equipment performance. As

conceptualized, the expert controllers would perform the

following functions:

-13-

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(1) Process Control - The expert process controller

interprets assimilated data from process sensors.

This information is evaluated against the

knowledge base with subsequent diagnosis, and

corrective action derived for identified process

anomalies. As an example, the disruption of power

to ' the furnace during the growth cycle will

require a process planning decision to determine:

o Which furnace cells, if any, should be

cleared, and plan for the recycling of

source crystals, and discarding of waste.

o Optimum schedule to provide ingots which

can yield one or two wafers, instead of

three, and complete, the wafer processing.

(2) Maintenance Control - The expert maintenance

controller receives inputs from the furnace and

slicing/polishing equipment monitors. As

equipment anomalies are interpreted, the

controller then flags abnormal operation before

hard failure occurs. As the expert system evolves

it will ultimately isolate the equipment fault,

diagnose the cause, and indicate methods of

handling the function.

-15-

3.3 MICROELECTRONICS CHIP PROCESSING FACILITY DESCRIPTION

Design requirements for this facility are based on the

seven mask process for GaAs Very Large Scale Integrated

microelectronics manufacturing developed by General

Electric. This is a multi-step process which starts with a

polished wafer and ends with one which requires only

packaging functions which are more cost-effectively

performed back on earth, as shown in Figure 3.3-1.

1 1 1

f-MAHOMfcrmin 1 I 1

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ITruAHoiRinviin

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, kMTLAMTII-l I MnAtnVUUnt 11. ALLOT CWTACT1 IKSUUTO* II. VOTTIR1

Figure 3.3-1. GaAs VLSI Fabrication Schematic 7 Mask

Process

This process is similar to that currently used for

silicon chip manufacturing, but requires fewer steps. The

current trend is toward totally dry processes, which is by

far the easiest way for implementing such a facility in

space, because any process involving management of fluids

would prove very difficult in the microgravity and high

vacuum environment.

-16-

Seven subsystems are required to manufacture GaAs

chips. These subsystems are diagrammed in Figure 3.3-2,

which also defines the individual steps of the process flow

in sequence and an estimate of the time required by each

subsystem for each step. Note that many passes are

required through the E-Beam Direct Writer, while only two

or three passes are required for other subsystems.

Presuming that only one of each of the subsystems is

utilized in the facility design, the automated handling of

wafers requires versatile teleoperators and/or robotics,

and complex scheduling to accomplish an efficient

processing rate.

21

PLASMADEPOSITIONSUBSYSTEM

1.2 MIN

(A)

10

22

IONIMPLANTSUBSYSTEM

(E)

.2 MIN

(B)

PHOTORESISTSUBSYSTEM

1.2 MIN

11 15 18

RAPIDANNEALSUBSYSTEM

(F)

.3 MIN

14

26

1216192327

.. 5 (D)REACTIVEION ETCHSUBSYSTEM

1.2 MIN

20 24 28

(0E'BEAMDIRECT WRITESUBSYSTEM

2.0 MIN

13

(G)SPUTTERSUBSYSTEM

.7 MIN

17

I(H)

INSPECTIONSTATION

1.0 MIN

I

29

25

Figure 3.3-2. Microelectronics Chip Processing Flow

-17-

All subsystems used in the conceptual design existtoday or are in;an advanced state of development, but they

are in earth-based configurations. Each is made by several

manufacturers and usually are delivered and incorporated

into microelectronics assembly lines as separate units.

Each has their own command and control hardware and

software, vacuum chambers, and raw material and waste

material handling equipment.

Wafers are generally passed manually in cassettes

between the subsystems in clean rooms designed to filter

air to the Class 100 to 10 level. Even with this level of

cleanliness, contamination is a problem with silicon based

chips: GaAs chips will be even more vulnerable, especially

if chip density increases tenfold or more as expected.

Several manufacturers, including VARIAN, are developing

more fully automated assembly lines incorporating robots

and conveyer systems to replace people in the transfer of

cassettes from, one subsystem to another in an earth based

environment, but the vacuum management is still a major

hurdle in achieving full automation. This problem would be

overcome in the space environment, where a full vacuum

facility is possible.

The GE concept for this facility is therefore one which

is based on the state-of-the-art subsystems, each without

complex vacuum equipment and individualized control

hardware and software. Working meetings with each vendor

resulted in a repackaging of each subsystem and integration

into a fully automated space facility as shown in Figure

3.3-3.

-18-

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-19-

Robotics are used to transport wafers in cassettes to

each subsystem in the desired sequence. Control is highly

automated, but supervised and occasionally monitored on the

ground and in a pressurized laboratory module by a space

station crewman. A distributed, fault-tolerant data system

is required to manage each subsystem and the robotics and

other material handling mechanization.

Crew access is provided for repairs and maintenance as

a starting point for this concept. After use in space, the

facility should mature, where nearly all repairs, servicing

and maintenance would be accomplished through teleoperators

and robotics remotely controlled by the software executive

controller and the on-board crew.

-20-

.3.4 GaAs MICROELECTRONICS CHIP PROCESSING .FACILITY

_.-,... AUTOMATION REQUIREMENTS . .. - .,. ; , - ; I . . , • , . , ; . „ ; : ,,

' • • _ • " ' .-' . • , • • ' ! •-.'•'• * * ": -^ '".. ' •• , ' ' ' • ' " . • ' ' .'.'•) V-! '; '• ' .'

...., ? Automation. requirements, are summarized :.In Figure

.3...4-1. Details are contained, in Volume II. , ; _ ,

In addition to ...the . state-of-the-art mechanizatipn

required for each subsystem process, robots are

conceptualized - for transfer' of : wafer, cassettes .between

subsystems.. These robots, would . be programmed, to-work

together, to move the wafers from, sub system,-.-to subsystem

quickly and efficiently, ;.and to perform cert.ain servicing

and maintenance functions as well. This requires automatic... - . • • 'V -• .^ . . -. .-• i ' •' • • J. , . . .•- - . .

change out of end-effectors, and reprogramming of. operating

profiles.

Software and sensors will be used to control the

process most efficiently by optimizing robot movements to

prevent interference between robots. For example, the

executive controller must know where all arms of each robot

are located, its motion, and its current task, and

coordinate activities between them.

Each robot is equipped with both vision systems and

tactile sensors to precisely locate input and output

devices for the subsystems, to retrieve stray containers or

fragile wafers, and to perform maintenance functions while

the other accomplishes routine processing.

Artificial Intelligence (AI) will be used to identify,

troubleshoot, and handle anomalies associated with

subsystem processing and maintenance. The complexities of

chip fabrication, coupled with the uncertainties associated

with space manufacture give rise to the need for an

integrated "expert" system. Expert process and maintenance

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controllers offer a knowledge-base from which the SpaceStation operator can draw detailed explanations to

implement timely process adjustments and equipment repair.

As envisioned, the expert controllers would perform the

following functions:

(1) Process Control - The process controller

assimilates specific online data from subsystem

process sensors and inspection probers, and in

turn interprets process anomalies and generates

appropriate responses. Often the generation of

appropriate responses requires simulation of the

potential effects of suggested corrective

actions. This differs from conventional computer

controlled feed back systems in that it can

respond to complex situations by applying domain

expertise to diagnose and correct deficiencies.

The process controller will also make planning and

scheduling decisions as process adjustments are

implemented.

(2) Maintenance Control - The maintenance controller

assimilates real time data from subsystem

equipment and consumable monitors to interpret

equipment anomalies. As anomalies are identified

the expert controller can implement maintenance

tests, note possible deviancies and flag abnormal

transient operation prior to hard failure. The

expert system can isolate a fault, diagnose the

cause, and suggest or implement corrective repair.

Periodically, an electrical probe test will be

performed on selected finished wafers. This consists of

performing up to 73 electrical measurements at various

points on a selected wafer to determine quality and process

accuracy. The process will be accomplished automatically

as it is now, however artificial intelligence techniques

need to be applied to efficiently determine the cause of

any anomalies and appropriate corrective actions.

-23-

4.0 CONCLUSIONS

The two manufacturing concepts developed in this study

represent innovative, technologically advanced

manufacturing schemes. The concepts were selected to

facilitate an in-depth analysis of manufacturing automation

requirements in the form of process mechanization,

teleoperation and robotics, and artificial intelligence.

While the cost-effectiveness of these facilities has not

been analyzed as part of this study^ both appear entirely

feasible for the year 2000 timeframe. The growing demand

for high quality gallium arsenide microelectronics may

warrant the ventures.

The evolution of enabling technologies for space

manufacturing will require detailed planning, and

coordination with the design team. To facilitate the

generation of a responsive automation plan, a list of

Generic Space Manufacturing Activities was developed from

the McDonnell Douglas Generic Space Activities list (see

THURIS Report for activity definitions). This list, as it

appears in Figure 4.0-1, was further developed to reflect

the degree of automation and associated technology

requirements necessary to perform each of the activities

over four time phased periods. The figure accurately

represents the intimate involvement of man in the process

loop at IOC, and the subsequent scaling down of man's role

with time to accommodate the ultimate autonomous concept.

Figure 4.0-2 depicts the evolution of automation

technologies for space manufacturing from initial

development studies, through IOC, to the ultimate

autonomous manufacturing facility. This technological

progression enhances the stated Space Station technology

goals of "maintainability, autonomy, long life, human

productivity, evolution, and low life-cycle costs".

-24-

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Additional work must be accomplished to develop highly

automated facilities such as those described beyond the

conceptual stage. Such automated equipment is essential

for cost-effective space manufacturing.

Very versatile industrial robots are in extensive use

today. Those conceptualized for use in space will be of a

very different design. They must be able to operate in a

hostile environment of hard vacuum with potentially high

thermal gradients and radiation. While micr.ogravity allows

their design to be lightweight, different kinematics and

dynamics will exist. Different approaches to actuation

devices and end-effectors must therefore be developed.

While the lack of gravity reduces grip and wrist forces,

gravity can no longer be used as a helper to catch things

or hold them in place. Since the robots must be versatile

enough to handle different materials and various repair and

maintenance functions, a quick change end-effector

replacement system will be required. Many of the complex

maintenance and repair functions will be initially done by

teleoperators; therefore, feedback devices, including

visual and tactile sensors, must be developed well beyond

todays' designs.

As more autonomy is developed, the more reliable,

serviceable, easily repairable, and accurate the equipment

must be. It will be difficult to provide the space station

crew the kind of access, information and resources needed

to adjust or repair highly automated systems in the

confines of a space facility to the degree possible in an

earth-base factory.

The major challenge of space manufacturing is

maintenance and repairs. Without the automation

capabilities to accomplish these functions, manufacturing

in space will be unattainable.

-27-

Artificial Intelligence can be developed for

manufacturing facilities which will provide efficient

control of troubleshooting, maintenance and corrective

action options. Development of "expert systems" to do the

job even better must await expertise to be gained in

operating the system during development and in space. This

means any program must walk before running by initially

providing crew access where possible. As experience isdeveloped, more hardware and software automation can be

accomplished, thus making space factories more productive

by trading access space for more equipment and materials

storage. The space crew will contribute much to this

evolution, and will supply much of the expertise needed to

develop expert systems for maintenance and repair

automation.

Expert systems are very difficult to develop. A data

base must be developed and expanded as a facility matures.

Therefore more human involvement will be required early in

the evolution of each facility. Elements of an expert

system can be developed individually, but need to be

structured to fit effectively into the total system as it

evolves.

-28-

5.0 RECOMMENDATIONS

We must "get on with the show": to do so means that

research and development must be accomplished in many areas

and certain space hardware developed and proven.

The following five specific programs are recommended as

a result of this study; they are believed to be essential

for many other space manufacturing applications as well.

(1) Space Manufacturing Concepts Development Study

Several manufacturing design concepts, including those

described in this report, would be more fully developed

to define system requirements, preliminary facility and

automation designs, maintenance and repair scenarios,

space station interfaces, cost-effectiveness, and

evolutionary growth of each through a twenty year

period. The concepts would be chosen to assure maximum

applicability for automation of manufacturing processes

and associated maintenance and repair for all potential

space manufacturing applications.

(2) Space Robotics System Experiment

A general purpose, hybrid robot would be designed for

experimental evaluation in space. A hybrid robot

normally operates under program control with sensory

feedback, but for certain applications can be remotely

controlled as a teleoperator. A modular design will

be considered, so that combinations of different

configurations can be evaluated. Self maintainability,

the capability of one robot to perform maintenance,

repair, and servicing as required for itself or for

another robot, will be explored.

-29-

Performance and design requirements would be determined

using the Space Manufacturing Concepts Development

Study as the primary reference, and reviewed by an

independent industrial/university committee. After

approval, the design would be fully developed, and an

experimental robot, together with its controller and a

variety of sensor systems, actuators, tools and

end-effectors manufactured, tested and flown as

experiments on the Shuttle by 1990. Experiments would

concentrate on maintenance and repair activities, but

also investigate materials handling tasks.

(3) Materials Management Study

Space-based handling of the various raw materials

required for space manufacturing,and the handling and

disposal of waste products and by-products would be

studied. Gaseous, liquid and solid waste products

would be included and concepts developed for handling

of hazardous, valuable and unstable materials in the

space environment. Servicing schemes for replenishment

and disposal would also be addressed.

(4) Materials Handling Experiments

Experiments in materials handling which are necessary

for a variety of manufacturing applications would be

flown on shuttle in the 1989-1991 time frame. Included

would be experiments in gaseous, liquid, and solids

handling of raw and waste materials and by-products,

selected from results of the Materials Management

Study. Handling of toxic materials necessary for

likely space manufacturing systems and collection of

dust-like particles resulting from slicing and

polishing operations would be candidate experiments.

Some experiments would be integrated with the Space

Robotics System Experiment.

-30-

(5) Space Manufacturing Artificial Intelligence

Applications Study

A university/industry team would study specific

concepts selected from the Space Manufacturing Design

Concepts Development Study to define conceptual

artificial intelligence system designs for control,

maintenance, troubleshooting, and corrective actions

required to operate the facilities. The data

management system requirements for these AI concepts

would be sized and interfaces with the Space Station

Data Management System (DMS) defined thus providing the

foundation for full development of Space Manufacturing

AI applications. This effort should commence as soon

as possible because of the potential impact on Space

Station DMS architecture.

Space manufacturing activities must be closely

coordinated with other Space Station activities. Impact

assessments need to be conducted during Phase B studies to

ensure compatibility of manufacturing missions with Space

Station operations. Manufacturing interfaces that have

been identified as requiring further evaluation by Phase B

contractors include power, thermal, data handling,

servicing and waste management.

o Power - Further study to determine power

distribution impacts on process scheduling;

scarring study to accommodate power expansion

requirements beyond IOC; assessment of GaAs

crystal growth potential for manufacturing solar

arrays to create additional/independent power

sources.

-31-

o Thermal - Study to assess the effects of thermal

shadowing on manufacturing processes; trade study

to evaluate centralized vs distributed control of

temperatures; assessment of the economics of

recovering Space Station waste heat energy or

solar energy to help drive furnaces.

o Data Handling - Study to determine required levels

of language, capacities and rates; projection of

data handling requirements for the ultimate

manufacturing concept to allow sufficient scarring

to accommodate evolving Space Station

manufacturing facilities.

o Servicing - Study to assess a universal Space

Station approach for raw materials, gas and fluid

handling, study to determine problems associated

with handling toxic materials/gases.

o Waste Management - Study to resolve waste

collection vs dumping trade-offs; evaluation of a

common waste collection module to be launched from

the Space Station for incineration by the sun.

These studies and experiments will help develop new

technologies required for space manufacturing. The studies

will also stimulate interest in the manufacturing

industries through involvement and understanding of the

benefits of manufacturing in space. With the desire of

American and foreign industries to reap these established

benefits, the future of the Space Station Program will be

assured.

-32-