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					                     NATIONAL AERONAUTICS
                     AND SPACE ADMINISTRATION
                     Ames Research Center




                               Guidance, Control and Simulation
                                of an Autonomous Lunar Lander


         Corey Ippolito
Carnegie Mellon Innovations Lab (CMIL) /
      Carnegie Mellon University
Adaptive Controls and Evolvable Systems
      (ACES) Group / NASA ARC
     NASA Ames Research Center
       Moffett Field, CA 94035




                     Khalid Al-Ali                            Jeremy Frank                Kalmanje Krishnakumar
        Director, Carnegie Mellon Innovations Lab   Planning and Scheduling Group Lead       ACES Group Lead
               NASA Ames Research Park                     Code TI / NASA ARC               Code TI / NASA ARC
                 Moffett Field, CA 94035               NASA Ames Research Center         NASA Ames Research Center
                                                          Moffett Field, CA 94035          Moffett Field, CA 94035
ALDER Project Overview                                  NATIONAL AERONAUTICS
                                                        AND SPACE ADMINISTRATION
                                                        Ames Research Center




   Autonomous Lander Demonstrator
   The goal of ALDER is to demonstrate the practical use of
    autonomy in spacecraft by implementing autonomous
    operation of lunar injection, cruise phase, lunar landing and
    mobile surface operations.
   NASA Ames Research Center, Code TI
      ◦ Lead by the Planning and Scheduling Group /
        Smart Spacecraft Working Group (Jeremy Frank)
      ◦ Controller Design and Simulation
        Under the Adaptive Control and
        Evolvable Systems Group
        (Kalmanje Krishnakumar) and
        CMIL (Khalid Al-Ali)
Mission Outline                                          NATIONAL AERONAUTICS
                                                         AND SPACE ADMINISTRATION
                                                         Ames Research Center




     Launch Vehicle: Suggested Design for Falcon 9 or Delta II
      2925H-10L Launch Vehicles
     Mission Duration for 10-14 Days,
     Entire Mission Cost: ~$210M (JPL Team X Study)
     Controlled soft landing near equator on Earth side, landing
      in sunlight.
     Perform scientific measurements at landing site.
      ◦ Number of possible goals, including rock/soil samples,
        spectrometers, ground penetrating radar, magnetometer
        measurements, seismometer, etc.
     “Hop” to next location, roughly 1km from last
      landing site.
      ◦ Take off from surface
      ◦ Lateral Transfer
      ◦ Land
     Repeat scientific measurements, hop
      to the next site.
        Hop Mission Profile                                                       NATIONAL AERONAUTICS
                                                                                  AND SPACE ADMINISTRATION
                                                                                  Ames Research Center




Hop Mission Leg Profile
                                                                        A   Receive “HopTo” Cmd

                                                                            Receive “LandAt” Cmd
                                                                        B


                                                                                        8. Hover To
                          5. Coast/Orient for Retro-Burn
                                                                                            Landing
                                                        6. Retro-Burn                   Coordinates
         4. Perform Ballistic Burn
                                                                                    B
                                                            7. Hover 30m AGL
         3. Orient for Ballistic Burn                       (Wait for Landing
         2. Pre-Burn                                        Coordinates)



                                                                                9. Land
A        1. Liftoff


    LA (Lunar Axis Reference Frame)
                                        ~1km Distance
Autonomy Technologies   NATIONAL AERONAUTICS
                        AND SPACE ADMINISTRATION
                        Ames Research Center




   Europa: Planning
    and Execution
   HyDE: Integrated
    System Health
    Management
    (ISHM)
   SHINE: Reflexive
    ISHM
   IDEA: Reasoning
   Vision
    Workbench:
    Vision Processing
    and Stereo Image
    Correlation
   Reflection
    Architecture:
    Guidance, Control
    and Simulation
                  Lunar Lander Design                                                 NATIONAL AERONAUTICS
                                                                                      AND SPACE ADMINISTRATION
                                                                                      Ames Research Center




 Mass                                                      Sensors
          Dry   Mass: 53kg                                       Officine GalileoAA-STR star tracker
          Fuel  Mass: 10kg                                       Draper Labs MEMS IMU
 Propulsion                                                             Simulated with Crossbow NAV420
                 Nitrogen Tetroxide (N204) and Hydrazine
          Bi-Prop-                                                       IMU Model
        (N2H4)                                                    Radar Altimeter
       600N Main Thrusters                                              Simulated with CMU MAX Sonar
       Four 30N Attitude Control Thrusters                               Model, 5-Ray Casts into Scene
 Power                                                           Stereo-Pair Cameras (1.7m Baseline)
       Li-Ion (200W-h / 3.6kg)                                          MSL MARDI-like imagers
       Solar Array Area: 2.55 m2                                         (600g/10W/4ms capture time,
                                                                          1600x1200/66oFOV)
Modeling and Simulation                                                            NATIONAL AERONAUTICS
                                                                                   AND SPACE ADMINISTRATION
                                                                                   Ames Research Center



                                        Box Inertias               Eight Spring/Dampers
                                                                   Force  kd  vrel  k s  stretch
                                        Cylinder Inertias


                                                                      Nine Rigid Bodies
                                                                 d
                                                                    p  R BI v B
                                                                 dt
                                                                 d
                                                                    ωB   J 1ωBJωB  J 1TB
                                                                                 ~
                                                                 dt
                                                                 d          1
                                                                    q   q q
                                                                 dt         2
                                                                 d
                                                                    v B   ωB  v B  R IBg  1 FB
                                                                 dt                               m


                                                                 Eight Revolute Constraints
                                                               J1v1  1ω1  J 2 v 2  2ω 2  c  C
Constrained Dynamics Model
    Nine Body System (13 States Each)                <= 12 Contact Constraints
                                                    J1v1  1ω1  J 2 v 2  2ω 2  c  C
    Eight Hard Equality Constraints
    Four Dynamic Constraints
    Up to 12 Temporary Contact/Inequality Constraints
    Runge-Kutta 4th Order Integrator
    Two LCP Solvers:
      Iterative Step Solver (Inner Integration Step Solver)
      Approximate Constraint Solver (Outer/Final Integration Step Solver/Pivoting Method)
Modeling and Simulation                                  NATIONAL AERONAUTICS

Sub-System Models                                        AND SPACE ADMINISTRATION
                                                         Ames Research Center




      Electrical
       ◦ First-Order Approximate Electrical Simulation
       ◦ NiMH Battery Discharge Curves




      Propulsion
       ◦ First-Order Thruster Dynamics
      IMU and Sensors
       ◦ IMU+GPS Terrestrial Type Simulation
         (Crossbow NAV420 Model)
       ◦ Altimeter Simulated with modified
         CMU MAX Rover Sonar Model
Flight Management
Computer (FMC)
Ballistic / Retro Burns                                  NATIONAL AERONAUTICS
                                                         AND SPACE ADMINISTRATION
                                                         Ames Research Center




Ballistic Burn Calculations




                                 K = ~1km Distance
           Phase I:                 Phase II:                Phase III:
            Burn                     Coast                     Burn
           T=Tmax*sin                   T=0                 T=Tmax*sin

             (dt=A)             (dt=B)                        (dt=C)
     t=0                 t=A                         t=A+B             tf=A+B+C

  = 45deg                                                              = -45deg
                               AC
    h(0) = 0                                                               h(tf) = 0
dh/dt(0) = 0                        2T                               dh/dt(tf) = 0
                               B      g C
    x(0) = 0                        gm                                  x(tf) = K
dx/dt(0) = 0                           Km                              dx/dt(tf) = 0
                               C
                                      2T    
                                      gm  1
                                    T       
                                            
              FMC Components                                                                                        NATIONAL AERONAUTICS
                                                                                                                    AND SPACE ADMINISTRATION
                                                                                                                    Ames Research Center
                         Flight Management Computer (FMC)                               «enumeration»
                                                                                     eFMCEngagementMode
                                                                                  +FMCMODE_DISENGAGED
              The FMC is the main object, responsible for maintaining and all     +FMCMODE_PILOT_ATTITUDE
             the controller’s components, and distributing messages and data.     +FMCMODE_HOVER
                                                                                  +FMCMODE_FMC_ENGAGED
                                                1


                                                                                                               1
         1                        1                               1
     COM            Command Sequencing               Hop Plan/Trajectory                            Flight Control System
                        Unit (CSU)                       Generator
 The COM is                                                                        The responsibility of the plan generator is to
responsible for     The CSU is responsible          The responsibility of the   generate the hop mission plan. This plan includes
communication      for maintaining the active         plan generator is to                  main engine firing times.
with the rest of    list of commands as the         compute the firing times                                  1
  the system.         mission progresses in            for the hop’s burn
                                                                                                    1                             1
                   time. The CSU provides                    phases.
                     accessors to allow the                                     Main Engine Control                   Attitude Control
                    FMC to add and remove                                         System (MECS)                        System (ACS)
                            commands,
                                                                                  The responsibility of              The responsibility of
                                 1                                              the plan generator is to           the plan generator is to
                                                                                    generate the hop                   generate the hop
                                 0..*                                              mission plan. This                 mission plan. This
                                                                                   plan includes main                 plan includes main
                          Commands
                                                                                  engine firing times.               engine firing times.
                 Commands are responsible for                                       MECS Modes:
                                                                                    Disengaged
                                                                                                                     ACS Modes:
                                                                                                                     DISENGAGED
               setting the ACS and MECS modes                                       EngOn
                                                                                    EngOff
                                                                                    AlitudeAttain
                                                                                                                     ATTITUDECMD
                                                                                    AltitudeHold                     LATSPEEDCMD
                                                                                    VSpeedCmd
                                                                                                                     LATPOSCMD
FMC Updates   NATIONAL AERONAUTICS
              AND SPACE ADMINISTRATION
              Ames Research Center
Hop Command Sequence
        Attitude Control System   NATIONAL AERONAUTICS
                                  AND SPACE ADMINISTRATION
                                  Ames Research Center


ACS Modes:
DISENGAGED
ATTITUDECMD
LATSPEEDCMD
LATPOSCMD
Single Axis Attitude Control                                                                  NATIONAL AERONAUTICS
                                                                                              AND SPACE ADMINISTRATION
                                                                                              Ames Research Center




                                                       2


                                                                           u  1
                              IV
                                    u0                            
                                                                           I
                       
                   

                                                                                    2         1
                                     1                            1
                            2


                                     III                                       II        
                           u  1                                        u0
                                                




                                           Phase Plane Control Logic

 Widnall, W. S., “Lunar Module Digital Autopilot,” Journal of Spacecraft and Rockets, Vol. 8, No. 1,
 1971, pp. 56-62.
          Main Engine Control System                                                                               NATIONAL AERONAUTICS
                                                                                                                   AND SPACE ADMINISTRATION
                                                                                                                   Ames Research Center



    MECS Modes:
    Disengaged
    EngOn
    EngOff
    AlitudeAttain
    AltitudeHold
    VSpeedCmd

                                              Altitude Hold Controller

                               h *
                                *T 0
                                        hcmd                           
                                                                if h0  0  h0  hcmd 
                                                                   

     State.Ori                  h T  hcmd
                               
                                                                        
                                                                if h0  0  h0  hcmd 
                                                                   
                                                                        
                                                                                           ME Command

                      FireME                                  if h0  0  h0  hcmd 
                                                                                            (On/Off)
    State.Pos                       false
  State.Alt(AGL)
                               
                                   true                                
                                                                 f h0  0  h0  hcmd 
                                                                   

m_cmdAltitude_m_agl
                                h0  hcmd
                                                                        
                                                                       if h  0
                                                                             0   
                                                  1         
                                                            h 02
                                           h*                       h
                                                  2     z  z T  0
                                                          ˆ      ˆ
                                                     g  wa ba 
                                                              m   
                                                                                                        Position/Mode:
                                                                                                        1 / AtitudeHold
                                                                                                        2 / Disegaged
                                                                                                        3 / VSpeed
                        State                                                                                              ME Thruster
                       VSpeed                                                                                               Command

                               VSpeedErr
                                                   VSpdErr to
 m_cmdVSpeed_mps         +/-
                                                   METhruster



Pilot ME Command
          Simulation Environment                               NATIONAL AERONAUTICS
                                                               AND SPACE ADMINISTRATION
                                                               Ames Research Center




System        FMC Mode       System
Control      Control Panel    Time
 Panel                       Window          Scene Visualization




   Primary     Navigation    Graphs    Stereo
    Flight      Display                Camera
   Display                            Viewports
Videos / Demo   NATIONAL AERONAUTICS
                AND SPACE ADMINISTRATION
                Ames Research Center
                     NATIONAL AERONAUTICS
                     AND SPACE ADMINISTRATION
                     Ames Research Center




                               Guidance, Control and Simulation
                                of an Autonomous Lunar Lander


         Corey Ippolito
Carnegie Mellon Innovations Lab (CMIL) /
      Carnegie Mellon University
Adaptive Controls and Evolvable Systems
      (ACES) Group / NASA ARC
     NASA Ames Research Center
       Moffett Field, CA 94035




                     Khalid Al-Ali                            Jeremy Frank                Kalmanje Krishnakumar
        Director, Carnegie Mellon Innovations Lab   Planning and Scheduling Group Lead       ACES Group Lead
               NASA Ames Research Park                     Code TI / NASA ARC               Code TI / NASA ARC
                 Moffett Field, CA 94035               NASA Ames Research Center         NASA Ames Research Center
                                                          Moffett Field, CA 94035          Moffett Field, CA 94035

				
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