1. Algorithm Design for Crossing and Passing Applications John Anderson and Colin Goodchild University of Glasgow, UK Thierry Miquel DSNA, Toulouse, France ASAS-TN2 2 nd Workshop Rome 3-5 April 2006

2. page 2 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Contents  Description of selected ASAS C&P applications –ASAS manoeuvre types –ASAS airborne operational logic –ASAS implementation and data sources  Synthesis of ASAS resolution manoeuvres –Approaches to conflict detection and resolution –Sources of uncertainty –Robust ASAS manoeuvres  Current status and planned activities

3. page 3 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS C&P Applications in Radar Airspace  Selective C&P applications and operational procedures in radar airspace are defined in deliverables D1.1 and D1.3: ASAS C&P ApplicationASAS Manoeuvre Class  Co-altitude pass behind  Co-aItitude pass in-front  Climbing pass behind  Descending pass behind  Turning point route  Offset route

4. page 4 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Co-altitude Applications Turning Point RouteOffset Route

5. page 5 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Climb/Descent Applications

6. page 6 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Generic Features of ASAS C&P Applications

7. page 7 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Generic Features of ASAS C&P Applications  Finite time-horizon (lookahead time 5-10 minutes)  Fixed topology manoeuvre classes  Manoeuvre envelope constraints  Lateral manoeuvre requirement only  A priori specification of resolution manoeuvres via FMS/Autopilot with scope for limited adaptation following initiation of manoeuvre  Third-party aircraft assumed isolated from ASAS designated pair

8. page 8 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS C&P Operational Phases Set-up Phase Identification Phase Clearance Phase Execution Phase Termination Phase Controller Flight Crew

9. page 9 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS Airborne Operational Logic test conflict test resolution feasibility review delegation update resolution manoeuvre execute resolution manoeuvre test lateral separation test clear of traffic test deviation resume own navigation feasible not_feasible commit conflict no_commit no_conflict continue_delegation return_delegation clearance_issued conformance non_conformance clear no_deviation deviation not_clear separation no_separation clear_of_traffic_acknowledged Clearance Execution Termination ATCo responsible for separation Abort phase

10. page 10 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS Resolution Implementation  Resolution control: –Point based (FMS) –Velocity based (Autopilot) NavigationControl Parameters FMS2D TCP’s AutopilotTV’s (Speed, Heading)

11. page 11 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS Data Sources ADS-B messages from other aircraft ASAS algorithms Flight plan ASAS resolution controls Ownship navigation data and dynamics Aircraft performance Wind ASAS performance metrics Target ID ASAS application type ASAS manoeuvre class

12. page 12 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS C&P Conflict Resolution Problem Given:  the initial/current conflict geometry and broadcast aircraft states  the clearance aircraft performance and manoeuvre envelope  a time-horizon dependent on the manoeuvre envelope Find:  the ‘best’ nominal resolution manoeuvre compliant with the required separation criterion, acceptable deviation constraints and acceptable level of operational performance. Given:  the initial/current conflict geometry and broadcast aircraft states  the clearance aircraft performance and manoeuvre envelope  a time-horizon dependent on the manoeuvre envelope Find:  the ‘best’ nominal resolution manoeuvre compliant with the required separation criterion, acceptable deviation constraints and acceptable level of operational performance. ‘Best’ = Safe + Efficient + Robust

13. page 13 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Synthesis of ASAS Resolution Manoeuvres  Conflict resolution algorithms (state-based) –Geometric (NLR/NASA FreeFlight, MA-AFAS, INTENT, MFF, DAG-TM) –Graph-based search –Simulation-based optimisation (HYBRIDGE)  Nominal trajectory models –Piecewise-linear (constant velocity) segments –Physical trajectory segments (eg co-ordinated turn segments, constant Mach/CAS segments)  Uncertainty models/Conflict metrics –Nominal/Minimum separation –Worst-case/Minimum separation of extremal bound –Probabilistic/Probability of conflict

14. page 14 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS Manoeuvre Parameterisation I  Resolution manoeuvre parameterised by: –heading change α (discrete values) –heading change start time t 0 –heading change end time t 1

15. page 15 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 ASAS Manoeuvre Parameterisation II S - Straight Line Segment T – Constant Radius Turn Segment  Resolution manoeuvre parameterised by (Vilaplana (2002)): –discrete mode sequence and switch times

16. page 16 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Sources of Uncertainty  Trajectory prediction errors resulting from: –Flight mode errors/uncertainty in climb/descent –Wind and (vertical) wind gradient uncertainty –Aircraft performance errors –Aircraft weight errors –Aircraft turn dynamics omission –Flight crew response latency –(Post-COT) intent errors –ADS-B failures and data anomalies

17. page 17 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Robust Resolution Manoeuvres  Robustness to uncertainty in environmental parameters and processes –Attempt to design ‘tolerance’ to uncertain environmental parameters in ASAS resolution manoeuvres while satisfying safety and efficiency criteria. –Minimise ‘false alarms’ and unnecessary manoeuvres –Maximise safety

18. page 18 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Features of Robust Resolution Environmental Parameters Cost Function Variation Feasible Infeasible Feasible Infeasible Optimal Robust

19. page 19 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Candidate ASAS CR Algorithms  Geometric and graph-based search methods fulfil the dual requirements of simplicity and transparancy in the real-time synthesis of ASAS resolution manoeuvres.  The additional requirement of robustness to uncertainties in environmental and flight mode parameters can be incorporated implicitly in a search-based approach to resolution synthesis.  Both geometric and search-based resolution methods offer scope for limited real-time adaptation of the ASAS manoeuvre.  Search-based resolution methods can be modified to accommodate trajectory segment models in both co-altitude and climb/descent applications.

20. page 20 ASAS-TN2 2 nd Workshop, Rome 3-5 April 2006 Planned Activities and Deliverables ActivityDeliverablePlanned Date Survey of candidate CD&R processes and algortihms. (UoG) D2.123/12/05 Implementation of geometric and graph-based search methods in ASAS test-bed. (DSNA/UoG) D2.212/01/07 Development of the ‘robust’ manoeuvre concept (with particular emphasis on climb/ descent applications). (UoG) D2.312/01/07 Preparation of algorithms for advanced simulation. (DSNA/UoG) D2.409/03/07