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Jillian RedfernOrbital Express PresentationTITAN All-Hands07/08/2003

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Topics to be Discussed

• Orbital Express and Mission Manager

• TITAN’s role

• Progress

• Future work

• Suggestions

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DARPA’s Motivation

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Movie of Robotic Arm

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Movie of Direct Capture

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Program Plans• Develop and validate software for autonomous mission

planning, rendezvous, proximity operations and docking. • Design, fabricate, and test on-orbit robotic satellite

servicing, including fuel and electronics transfer, deployment of and operations with a micro-satellite.

• Design, fabricate, and test on orbit a modular micro-satellite for protection of stationary satellites.

• Perform utility assessments of on-orbit servicing in conjunction with operational customers and plan for technology transition.

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Main Operations

– Guidance, Navigation, & Control– Capture

• Free Fly Capture (With Robotic Arm)• Direct Capture (With Grappling Mechanism)

– ORU Transfer• NextSat to ASTRO (With Robotic Arm)• ASTRO to NextSat (With Robotic Arm)

– Fluid Transfer• NextSat to ASTRO• ASTRO to NextSat

– Mission Manager (Draper Lab’s part)

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Failure Concerns

• Top 12 Failures Which Require Autonomous Response• Fail to direct capture• Fail to free-flyer capture• AC1 fault which results in reboot• AC2 fault which results in reboot• AVGS fails during prox ops• MCU fail during arm use• Battery DOD above 75 (TBR) %• Fluid coupler fails to engage• Fluid coupler fails to disengage• Pump fails on• RCS jet fail during prox ops• Selected valves fail open or closed

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Draper’s Mission Manager

• Draper’s Mission Manager “looks” a lot like TITAN at the high levels

• Current thinking for fault diagnosis: – rule-based -- system engineer generated fault

response system which is pre-determined (simplifies Diagnosis and Planning step through database utilization)

• I want to add in a Diagnosis step through either TITAN or MINI-ME

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MM Executive

Database

Monitor

Sequencer

NEXTSatOEDMSAutoGdAutoNav CM FTAPS ASTRO

Commands

Resource Predictor

Contingency Responder

Response Messages

Mission Manager

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TITAN

Model-basedProgram

Titan Model-basedExecutive

Sequencer

Deductive Controller

ControlProgram

PlantModel

Configuration goals

State estimates

Physical Plant

Flight Control Software

Control actionsObservations

Mode Reconfiguration

ModeEstimation

s

Activity goals(from planner)

CCAs

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FTAPSModeling

(What Jillian has been up to)

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System (Extremely simplified)

2 Valves (not pyro)2 Fluid Transfer Tanks1 Pump1 Pressure Sensor2 Flow Sensor

Flow in both directions

*Assume valves open individually

Tank1 Tank2

Valve2

Valve1

PumpF2

F1

P1

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Fluid Transfer Tank Level (Tank1)

Broken

Filling/Emptying

Empty

Full

(P1 = Nominal)

(P1 = Low)

(P1 = High)

Pump = 1to2

Pump = 2to1

Pum

p =

2to1

Pum

p =

1to2

Pump = OffPump = Off

Pump = Off

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Fluid Transfer Tank Level (Tank2)

Broken

Filling/Emptying

Empty

Full

(P1 = Nominal)

(P1 = High)

(P1 = Low)

Pump=Off

Pump=Off

Pump=Off

Pum

p =

1to2

Pum

p =

2to1

Pump = 2to1

Pump = 1to2

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Propellant Isolation Valve Number 1

Unknown

Open

Closed

LeakingCm

d=O

penV

1

Cm

d=C

loseV

1

F1 = reverse

F1 = stagnant

F1 = forward

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Propellant Isolation Valve Number 2

Unknown

Open

Closed

Leaking

Cm

d=O

penV

2

Cm

d=C

loseV

2

F2 = stagnant

F2 = reverse

F2 = forward

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Pump

Broken

1to2

OffC

md=

Pum

p

Off

(NOT Valve2=open) OR (Valve2=open AND F2=forward)

(F1 = Stagnant) AND (F2 = Stagnant)

2to1

(NOT Valve1=open) OR (Valve1=open AND F1=forward)

Cm

d=PumpO

ff

Cm

d=PumpR

ight Cm

d =

Pum

pLef

t

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Initial State

• Pump = Off• V1 = Closed• V2 = Closed• Tank1Level = Full• Tank2Level = Empty • Pressure = High• Flow1 = Stagnant• Flow2 = Stagnant

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Nominal Scenarios

• When Tank1Level = Full, turn pump on right and open valve V1 and close valve V2

• When Tank1Level = Empty, turn pump off and close valve V1 and open valve V2. Turn the pump on left.

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Off-Nominal Scenario

• At t = 1– Pump = Off– Flow1 = Stagnant– Flow2 = Stagnant– V1 = Closed– V2 = Closed– Tank1Level = Empty– Tank2Level = Full– Pressure = Low

• At t = 2– Valve2_Command = open– Pump_Command = PumpLeft

• At t = 3– Pump = 2to1– Flow1 = Reverse– Flow2 = Forward– V1 = Closed– V2 = Open– Tank1Level = Filling– Tank2Level = Filling– Pressure = Nominal

• At t = 4– Valve1 = Leaking (Can I think of this as a fail to close?)

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Another Off-Nominal Scenario

• At t = 1– Pump = 1to2– Flow1 = Forward– Flow2 = Stagnant– V1 = Open– V2 = Closed– Tank1Level = Filling– Tank2Level = Filling– Pressure = Nominal

• At t = 2– Pump_Command = Off

• At t = 3– Pump = Off– Flow1 = Forward– Flow2 = Stagnant– V1 = Open– V2 = Closed– Tank1Level = Filling – Tank2Level = Filling– Pressure = Nominal

• At t = 4– Pump = Broken

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Failure Probabilities

• Valve1 – equal probability of failure• Valve2 – equal probability of failure• Pump – higher probability of failure• Tank1 – low probability of failure• Tank2 – low probability of failure

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Progress

• Extremely simple model has just now been compiled successfully

• I have not run the mof file through TITAN or even Mode Estimation

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Goals for Thesis/Project

• Model the rest of the system accurately– FTAPS– Capture

• Direct• Free-Flyer

– ORU Transfer

• Adapt TITAN/MINI-ME to my needs or at least demonstrate its diagnosis is better than a system engineer

• Help improve the utility of TITAN to other programs

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My questions to the group

• The monitor: I receive a lot of status updates from software and general system statuses. What can I do with those?

• Do I always assume the commands are getting to the correct components?

• Not sure whether I have hybrid capabilities with the monitor• Is there someone who is a better modeler than I in this group?• Why do we code it like this:

(off :documentation "The OFF mode."

:model (and

(= (flow ?valveName1) stagnant) (= (flow ?valveName2) stagnant) (= (pump_mode ?pumpName) off))