Some Real-Time Programs in Aerospace Industry by David Benavente-Sánchez

Simulation & Avionics Department, GMV SA ( Tail-Boom (GMV SA/CESA for EADS-CASA) Space Systems Engineering Division, DEIMOS-Space ( Galileo OSPF-SISA Algorithm, (DEIMOS-Space/LogicaCMG for ESA) Galileo OSPF-GSS Network Optimization Algorithm, (DEIMOS- Space/LogicaCMG for ESA) SPHYNX Re-entry vehicle (DEIMOS-Space/Alenia Spazio for ESA) Sample Projects

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 Air-to-Air Refueling Program for Airbus Tankers Phase A/B: Tail-Boom 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 Main Functions of the Tail-Boom Flight Control 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! Tail-Boom Control & Monitoring System Real-Time System

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 Galileo Orbit & Synchonization Processing Facility (OSPF), SISA Algorithm

SISA has 2 contributors: Estimation and propagation of SISE (main) Use of the navigation message  The user does not have the actual OD&TS 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 SISA Algorithm (definitions in the absence of clock errors)

Estimation of SISE: Kalman Filter

Propagation of SISE: Use of Transition Matrix

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 Galileo Sensor Stations Network Optimization Algorithm