Some Real-Time Programs in Aerospace Industry

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Some Real-Time Programs in Aerospace Industry

• by David Benavente-Sánchez

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Sample Projects

• Simulation Avionics Department, GMV SA
  (www.gmv.com)
• Tail-Boom (GMV SA/CESA for EADS-CASA)
• Space Systems Engineering Division, DEIMOS-Space
  
• (www.deimos-space.com)
• Galileo OSPF-SISA Algorithm, (DEIMOS-Space/LogicaC
  MG for ESA)
• Galileo OSPF-GSS Network Optimization Algorithm,
  (DEIMOS-Space/LogicaCMG for ESA)
• SPHYNX Re-entry vehicle (DEIMOS-Space/Alenia
  Spazio for ESA)

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Air-to-Air Refueling Program for Airbus
TankersPhase A/B Tail-Boom Control System

• Spec Preliminary Design of the Tail Boom
  Control and Monitoring System
• Key System Starting Requirements
• 3DOF roll-pitch joint, inner-tube extension
  (boom up to 17m)
• V-rudder aerodynamic actuation, hoisting outside
  envelope
• Boom operator console in pilot area
• No single point failures in the Control and
  Monitoring System

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Main Functions of the Tail-Boom Flight Control
System

• Operational Mode Handling hoisting, approach,
  connection, (automatic)
• Guidance
• Joint position or rates desired by operator
  (joystick with feel-force system)
• Automatic during connection (minimization of
  loads transmitted to receiver)
• Navigation
• Integration of LVDT/RVDT on joints and rudder,
  IMUs on tips, strain gauges, ARINC A/C flight
  data
• Estimation of low-freq flexible mode amplitudes
  (first bending and torsion)
• Several algorithms proposed
• Control
• MIMO gain schedule affected by low-frequency
  flexible modes

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Tail-Boom Control Monitoring System Real-Time
System

• Control Monitoring System Design Main
  Characteristics
• Duplex VME-based Architecture
• Distributed (Console and Flight Control System)
• RT Operating System VxWorks AE653 (ARINC 653
  compliant)
• Real-Time Program Analysis techniques would be
  particularly interesting in this project because
  it is required RTCA DO-178B level A safety
  certification!

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Galileo Orbit Synchonization Processing
Facility (OSPF), SISA Algorithm

• SISA (Signal-In-Space Accuracy) new concept in
  GNSS
• Each S/C provides its current SISA within the
  navigation message
• SISA bounds the error in pseudorange
  measurements for the worst user location and for
  the whole navigation message validity time
  interval
• SISA is an indicator of
• Integrity!
• Accuracy

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SISA Algorithm

• SISA has 2 contributors
• Estimation and propagation of SISE (main)
• Use of the navigation message
• The user does not have the actual ODTS
  estimation
• Instead, the navigation message approximates it
  with a set of 16 parameters
• Two sources of error now
• Fitting error
• Discretization of parameters to n bits

(definitions in the absence of clock errors)
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Estimation of SISE Kalman Filter
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Propagation of SISE Use of Transition Matrix
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Galileo Sensor Stations Network Optimization
Algorithm

• An additional GSS must be added (offline Galileo
  Ground Segment Design, online upon GSS
  operational contingency) always minimizing the
  worst SISMA achievable
• Finite (but maybe large) number of stations to
  select among
• Tree Search
• Level coincides with number of stations
• Expansion strategies
• Nearest set near the continuous optimal station
• All possible stations