Jillian Redfern

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Jillian Redfern Orbital Express
Presentation TITAN All-Hands 07/08/2003
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Topics to be Discussed

• Orbital Express and Mission Manager
• TITANs role
• Progress
• Future work
• Suggestions

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DARPAs 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 Labs 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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Drapers Mission Manager

• Drapers 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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Mission Manager
Database
MM Executive
Monitor
Contingency Responder
Resource Predictor
Sequencer
Commands
Response Messages
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TITAN
Titan Model-based Executive
Model-based Program
Activity goals (from planner)
Control Program
Sequencer
Configuration goals
State estimates
Deductive Controller
Plant Model
Mode Estimation
Mode Reconfiguration
CCAs
Control actions
Observations
Flight Control Software
Physical Plant
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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 Tanks 1
Pump 1 Pressure Sensor 2 Flow Sensor Flow in
both directions Assume valves open individually
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Fluid Transfer Tank Level (Tank1)
Pump 1to2
Pump Off
Pump Off
Pump 2to1
(P1 Nominal)
(P1 High)
Pump 2to1
Pump 1to2
(P1 Low)
Pump Off
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Fluid Transfer Tank Level (Tank2)
Pump 2to1
PumpOff
PumpOff
Pump 1to2
(P1 Nominal)
(P1 Low)
Pump 2to1
Pump 1to2
(P1 High)
PumpOff
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Propellant Isolation Valve Number 1
F1 forward
Open
F1 reverse
Leaking
CmdCloseV1
CmdOpenV1
Closed
F1 stagnant
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Propellant Isolation Valve Number 2
F2 forward
Open
F2 reverse
Leaking
CmdCloseV2
CmdOpenV2
Closed
F2 stagnant
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Pump
(NOT Valve2open) OR (Valve2open AND F2forward)
(NOT Valve1open) OR (Valve1open AND F1forward)
1to2
2to1
Broken
CmdPumpOff
CmdPumpRight
Cmd PumpLeft
CmdPumpOff
Off
(F1 Stagnant) AND (F2 Stagnant)
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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

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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

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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))