Model Based Design for Fuel System Development. Christopher Slack, Airbus 04 October 2017

Transcription

1 Model Based Design for Fuel System Development Christopher Slack, Airbus 04 October 2017

2 54,000 Employees 49.2billion Annual revenue* 6,726 Backlog 400 Operators 17,287 Aircraft sold 60 Produced monthly 10,561 Delivered 25,000+ Daily flights 2

3 L OUTR FEED 1 FEED 2 FEED 3 FEED 4 R OUTR HI LVL L OUTR FEED 1 FEED 2 FEED 3 FEED 4 R OUTR L MID L INR TRIM CTR R INR R MID HI LVL L MID L INR TRIM CTR R INR R MID OPEN SHUT OPEN SHUT ACTUAL (FOB) PRESELECT (PFQ) BATTERY NORMAL FAULT INCREASE DECREASE STATUS OVERFLOW SHUT DOWN System Development Perimeter and Interfaces Flame arrestor Air to Air Refuelling Flammability Reduction Fuel Pumps Burst Discs Pipes, Couplings Engines Refuel Panel POWER SUPPLY SHUTOFF TEST kg kg AUTO REFUEL Cockpit displays OFF MAN AUTO REFUEL REFUEL DEFUEL XFR APU EMERGENCY REFUEL / DEFUEL VALVES MODE SELECT PRESELECT Valves Fuel Gauging & Control Computers Compensators Densitometers Electrical Interfaces Gauging Fuel Probes Level Sensors Temp Sensors 3

4 Use of models (Amount / Fidelity) Model Use History Model Based System Engineering Model Based Design Model Based V&V Model Based Design A380 Model Based Design Desktop simulator A400M V&V Auto Test & SLDV A350 Fuel Virtual Integration Platform Textual Requirements A300 Textual Requirements A320 CofG Calcs Textual Requirements A330/A340 Specific, Targeted V&V A Functional Requirement Validation Iron Bird Time Fortran, HP Basic MATLAB, Matrix-X, Easy5, Statemate MATLAB, Simulink, Statemate MATLAB, Simulink, RTW, Stateflow MATLAB, Simulink, SysML, MATLAB, Simulink, Stateflow, SLDV, Stateflow, SLDV Simscape, 4

5 Towards Full MBSE System Requirement Authoring, Validation and Verification 5

6 Number of Mission in 200 nm block Model Based Design Lifecycle Tank Modelling: A/C - Output for Gauging & Fuel Management - Output for Wing design (stress, load, etc.) MG3 Architecture Design MG5 MG7 MG9 MG11 Inerting Certification using Modelling Mission Distribution AMO & FSP for Test Rig and A/CO Aircraft Range 1000's NM Multi-systems Detailed Design Fluid and Thermal modelling Integration Testing Systems Matlab Simulink for Fuel Management SSRD Req and detailed design Simulation Fuel Virtual Integration Platform to support system tests FVIP Desktop simulator for Validation of requirement Equipments and Verification of detailed design Desktop Simulator Model translation for software development Suppliers s/w dev 6

7 Model Based Design - In Practice Develop models to specify system functionality Describes behavioural & functional aspects Details become the System (and Sub-System) Requirements Exercise the model to Validate Requirements Delivered to Fuel System Supplier Model contains Requirements and intent Model execution provides system understanding Minimal Work to turn into Code Separate layer for independent validation Environment SATCOM voice & data HF / VHF voice & data TOP LEVEL REQ Air Traffic Control SITA/ARINC network FUNCTIONAL/ SYSTEM REQ LOW LEVEL EQUIP REQ LOW LEVEL EQUIP DEV 3D positions Radar Radar network Page 7

8 MBSE Functional System Requirements MATLAB/Simulink/Stateflow Application Development of Control System Reqts Normal and Failure Operating Modes Crew Procedures Control Logic separated from Aircraft Environ System Designers focus on Control Functions HMI Robustness & Validation Specialist Modellers focus on: Aircraft & Environmental Simulation Physics (Fuel, Thermal) Auto-Test Capabilities 8

9 MBSE Stateflow for Requirements Authoring Aircraft Fuel System Statecharts: Linked Requirements System Requirements Documents Cascade Requirements Database (DOORS) Separate Chart for each Major A/C Function Allows for collaborative development Transition booleans calculated externally Input from Simulink Stateflow graphical function Driven behaviour of Stateflow logic separated from driving conditions Allows easier readability and testing 9

10 Model Based Design - Reuse Integrated Desktop Simulator Requirements & Environment Model AutoCode using Simulink Coder Optional Interfaces to Cockpit Display & Flight Warning OCASIME, VIP & Aircraft -1 Entire Software Simulation Interfaces Identical to Full Flight Simulator Aircraft-0 (Iron Bird) Cockpit Avionics & Displays Integrated of Real & Simulated Systems Virtual Hosting of Supplier s Code Full Flight Simulator Single model for all platforms Training Flight and Ground Crews 10

11 Model Development Test/Verification/Validation Cycle Model V&V has to go through several loops When the model is the requirements, the distinction between Model Verification and Requirements Validation is somewhat blurred If a test fails, what is at fault? the requirement? the model? the test? Requirements Test Objectives Model Specification Test Objective Validation Test Scripts Test Script Validation MODEL Results & Problems Environment Model Verification Model Validation Requirement Validation 11

12 Using Simscape to Model A350 Refuel System Component export, parameter estimation And model simplification for Real Time performance 12

13 Use of Simscape Fuel Design Model Developed in Flowmaster Architecture and Component Performance Spec Model Only - not real-time Cannot produce C-Code or embedded simulations Flowmaster Diagram Exploiting new SimHydraulics Toolbox Mathworks Consultancy Airbus provision of core models and perf data Majority of development by Mathworks 13

14 Component Development Mapping of Flowmaster components to Simscape/ SimHydraulics equivalents Most 1:1 equivalents Some required customisation from base library Curve Fitting Toolbox Fit source data to SimHydraulics block equations Saved as Matlab Script for re-use 14

15 Library Construction and Parameterisation Component Library System Library Component Library to customise standard Hydraulic Library Components System Library contains System Level Components Each System Palette contains Multiple Components E.g. There are several different type of pumps System Palette System Palette constructed using MATLAB scripts Self Documenting Re-run if design model updated 15

16 Model Simplification Design Model has ~900 individual Components A reduction of the number of blocks by a factor of 10 can potentially yield a simulation speed improvement by a factor of 1,000. Reduction Strategies Reduce multiple serially Connected Pipes/Bends/Losses to a single Equivalent pipe/loss combination Design Optimisation toolbox Established Equivalent Parameters Reduction in the number of components Pipe components reduced from 290 to 60 Total Components reduced from 900 to 170 So would expect ~120 x speed-up 16

17 Model Reduction During Refuel or Defuel, certain valves are not in use Fluid network behind those closed valves do not contribute to pressure/flow calculations Therefore can be removed Reduced Model Complete Model Refuel from Left Wing Only This can be repeated for each combination of tank that needs to be studied. The reduced model can be constructed automatically with MATLAB scripts that analysis network topology. 17

18 Simscape Summary of Results Two system-level models of the Defuel system created in SimHydraulics One complete: all components required to model the system behaviour included One simplified: all isolated components located behind closed valves removed Performance of the simplified model sufficient for real-time Tested with Simulink Real Time on industrial PC Performance of the complete model not sufficient for real-time implementation, despite simplifications made. Depends on the solver chosen to a large extent Improves substantially from with later Simscape versions Near real-time performance in exploiting Simscape local solver New blocks and demos added to SimHydraulics as a direct result of this work 18

19 Code Efficiencies and Performance Enhancement Fuel Temperature Prediction Software 19

20 Temperature ( C) Fuel Temperature Prediction for Airlines An Exercise in Code Efficiencies T Convection Radiation network Inter-tank Fuel Transfer Conduction Sky Night/Day Buoyancy Solar radiation Emissivity from skin external heat source / sink Emissivity from skin Heating from earth 30 T Earth Comparison of Predicted and Measured Fuel Temperature Low outside temperatures with long exposure times Fuel temperature may drop close to or below freezing point Software written in MATLAB Predict fuel temperatures given Flight Profiles & Global Air 20 Temperatures Distance (nm)

21 Fuel Temperature Prediction for Airlines An Exercise in Code Efficiencies Intended Usage Y Flight Plan Fuel Temperature Prediction Cold Fuel? N Fly Route Run-Time ~ 40 seconds (reasonable) Actual Usage Flight Plan Flight Plan Flight Plan Flight Plan Flight Plan Flight Plan Flight Plan Flight Plan n Other Safety & Economic Factors Fuel Temperature Prediction Calculate Best Route Fly Route Up to 50 potential Routes Run-Time ~ 50 * 40 seconds = Half Hour BAD! 21

22 Using MATLAB Profiler to Identify Code Efficiency Bottlenecks Exploit MATLAB Profiler Built into MATLAB profile on ; run program ; profile viewer Creates timing profiles of every function called Look at the Self Time for time spent within function Profile Report highlights most expensive L.O.C. Iterative process to increase code efficiencies. 22

23 Average Simulation Time per Flight (s) Code Optimisation Strategies Equation Vectorisation Loop Unrolling Switch case statements Reduce volume of code inside each case Use c-mex for time-critical functions Check target platforms Minimise Globals Very slow in MATLAB Run-Time Improvements of Fuel Temperature Prediction Module Reduce calculations inside for loops Pre-calculate invariant parts of equations 5 Target Time 0 May Jun Jul Aug Sep Oct 23

24 Keeping Track of Mathworks Release Cycles Industry Model Testing 24

25 1 Valves 2 Modes 4 Recirc Inhibit Mass Engine Burn APU Burn Recirc Flow Jettison Altitude Pitch Roll Recirc_Inhibit Mach Air Temp FP Mux Flight_Profile 1 Jettison 2 Altitude [V] [M] Engine Burn APU Burn Recirc Rate Valve States Transfer Mode Tank Empty Flow Rates Valves_2_Flowrates Leak Flow Rates 10 [F] Flow Rate Leak Rate IRP_MODE_SELECTION Leaks Tanks function evaluate_conditions() 5.1.(2) { AR=... IRP_MODE[IRP_AUTO_REFUEL] &... ~IRP_MODE[IRP_MANUAL_REFUEL] &... ~IRP_MODE[IRP_TRANSFER] &... ~IRP_MODE[IRP_DEFUEL] &... ~IRP_MODE[IRP_OFF] &... Simulation.CG ~SOT_INITIATED; XFER=... Enable CG IRP_MODE[IRP_TRANSFER] Calc &... ~IRP_MODE[IRP_MANUAL_REFUEL] &... ~IRP_MODE[IRP_AUTO_REFUEL] &... ~IRP_MODE[IRP_DEFUEL] XCg &... ~IRP_MODE[IRP_OFF] &... ~SOT_INITIATED &... Pitch ~GND_SURGE_RELIEF_ACTIVE; DF=... Targ_Cg IRP_MODE[IRP_DEFUEL] &... ~IRP_MODE[IRP_MANUAL_REFUEL] &... ~IRP_MODE[IRP_AUTO_REFUEL] &... ~IRP_MODE[IRP_TRANSFER] Mom X &... ~IRP_MODE[IRP_OFF] &... Roll ~SOT_INITIATED &... ~GND_SURGE_RELIEF_ACTIVE; Mom Y IDLE=... IRP_MODE[IRP_OFF] &... ~IRP_MODE[IRP_MANUAL_REFUEL] &... ~IRP_MODE[IRP_AUTO_REFUEL] Tot Weight &... ~IRP_MODE[IRP_TRANSFER] &... Mass ~IRP_MODE[IRP_DEFUEL] &... ~SOT_INITIATED &... ~GND_SURGE_RELIEF_ACTIVE; CG Mux MR=... IRP_MODE[IRP_MANUAL_REFUEL] Cg_Calc &... ~IRP_MODE[IRP_DEFUEL] &... ~IRP_MODE[IRP_AUTO_REFUEL] &... ~IRP_MODE[IRP_TRANSFER] &... ~IRP_MODE[IRP_OFF] &... ~SOT_INITIATED; FAULT=... ~AR & ~XFER & ~DF & ~IDLE & ~MR; } 3 XCg 4 Targ Cg 6 Mom X 7 Mom Y 8 Tot Weight Volume Tank Empty Density Vol 2 Mass Simulation.Temperature Enable Temperature Program AFSME 3.2 STR 465 Date: Fri Jan 18 11:24: Ref: SCF/SYS/GEN/61/2623 Iss. 6 User Guide: SCF/SYS/GEN/61/2909 Mass Volumes Temp Mach Temperature (1) (1) 9 MANUAL_REFUEL Air Temp AUTO_REFUEL Temperature [AR &... Mass [XFER&... DELAY(D_GOS)] [(~GND_SURGE_RELIEF_ACTIVE &... DF IDLE) &... DELAY(D_GOS)] ~GND_SURGE_RELIEF_ACTIVE)... ~AR) SOT_INITIATED] MR_ SOT_INITIATED] AR_ Temperature [~XFER... TR_ CONF CONF SOT_INITIATED] CONF [F] Flow [DF]/d_i=0; [~DF] DF_ CONF [DF &... DELAY(D_GOS)] [V] [M] 3 Auxiliary Plot [SOT_INITIATED] [~DF SOT_INITIATED] Valves Modes 5 Flight Profile [Mode_Status[TR_SOT_EXIT] &... ~GND_SURGE_RELIEF_ACTIVE] CG Aux function GO_D = DELAY(d_t) [~IDLE... [IDLE &... Time Plotting FAULT SOT_INITIATED ] DELAY(D_GOS)] SURGE 5.1.(1) (1) TRANSFER [~IDLE] [IDLE]/d_i=0; OFF_ CONF (1) 5.1.7(1) Industry Model & Code Testing Aircraft Development 3-5 years, Mathworks upgrades every 6 months One solution to reduce cost of (continuing) upgrade cycles Testing infrastructure utilising customer models and MATLAB scripts Release Compatibility Performance Win-Win Situation: Value to Customers Reduced product upgrade cost Increased productivity Early knowledge of regression Value to Mathworks Compatibility testing Performance testing Increased tool adoption Simple 4-step process GUIs ITAR Rated Firewall Models Models AFSME Airbus Fuel System Modelling Environment GROUND_OPS/ 1 [DELAY(D_GOS)][((AR XFER... [MR FAULT]/d_i=0; [~MR] [AR]/d_i=0; [~AR] [~XFER] [XFER]/d_i=0; (1) (1) DEFUEL SOT OFF Secure Models Server 2 Tests & Results Establish NDA Package Models/Scripts Send Package Review and Act on Results 25

26 Summaries and Lessons Learnt 26

27 Lessons Learnt Deployment of MBSE As much about Competences as Technologies Skillsets & Mindsets Integration of Functional & Non-Functional models Model Build Reveals Emergent Properties Validation for free System difficult to model will be difficult to build/test Validation/Verification Testing A test that is more complex than that being tested is probably wrong Easy to be caught in the trap of Test for Success Testing for intentional but not unintentional behaviour Automated Test/Analysis allows regression testing Formal Proof more thorough than test scripts System Designers Focus on Designing the System The System Model is the System Requirements Extra functionality required to exercise the model are not requirements Need to clearly identify what are requirements and what are the extras Model Architecture Must match System Architecture Also conducive to multi-team development Easy for Designers can be Difficult for Simulators Engineers can be very ingenious Break downstream processes Model exchange with suppliers Automatic code generators Require adherence to Style Guidelines and Design Patterns 27

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