LOTNAV: A LOW-THRUST INTERPLANETARY NAVIGATION TOOL

Transcription

1 7th Internatinal Cnference n Astrdynamics Tls and Techniques LOTNAV: A LOW-THRUST INTERPLANETARY NAVIGATION TOOL 6-9 Nvember 2018 DLR Oberpfaffenhfen, Elecnr Deims Elecnr is the Deims trademark is the encmpassing trademark encmpassing the Elecnr the Grup s Elecnr cmpanies Grup s f cmpanies Aerspace, f Technlgy Aerspace, and Technlgy Infrmatin and Systems: Infrmatin Deims Systems: Space Deims S.L.U. (Tres Space Cants, S.L.U. Madrid, (Tres Cants, Spain), Madrid, Deims Spain), Engenharia S.A. (Lisbn, Prtugal), Deims Castilla La Mancha S.L. (Puertllan, Ciudad Real, Spain), Deims Space UK Ltd. (Harwell, Oxfrd, United Kingdm), Deims Space S.R.L. (Bucharest, Rmania) Deims Engenharia S.A. (Lisbn, Prtugal), Deims Castilla La Mancha S.L.U. (Puertllan, Ciudad Real, Spain), Deims Space UK Ltd. (Harwell, Oxfrd, United Kingdm), Deims Space S.R.L. (Bucharest, Rmania)

2 AGENDA LOTNAV: A LOW-THRUST INTERPLANETARY NAVIGATION TOOL INTRO: Mr. LOTNAV 1. TRAJECTORY GENERATION 2. MEASUREMENTS GENERATION 3. COVARIANCE ANALYSIS 4. SIMULATION 5. TRAJECTORY REOPTIMISATION CONCLUSIONS

3 INTRODUCTION LET ME FIRSTLY INTRODUCE YOU Mr. LOTNAV 15 years f develpment (pretty an ld guy in this field!) A lng recrd f successful applicatin in ESA missins A living tl, always lking fr perfrmances extensin and imprvement Definitely a reference pint fr new SW develpments in DMS

4 LOTNAV PHOTOBOOK INTRODUCTION EXOMARS GTOC BEPI COLOMBO LAGRANGE MISSION PHOBOS SAMPLE RETURN SOLAR ORBITER MARS SAMPLE RETURN

5 INTRODUCTION LOTNAV PURPOSES ptimised lw-thrust trajectry encunters with massive and minr bdies measurement simulatin fr OD cvariance analyses full Mnte Carl navigatin analysis lw-thrust guidance generatin interface with ther glbal trajectry ptimisatin tls trajectry re-ptimisatin after pssible failure scenaris

6 1. TRAJECTORY GENERATION INITIAL VALUE PROBLEM SOLVER SPICE recently added BOUNDARY VALUE PROBLEM SOLVER REFINED BOUNDARY VALUE PROBLEM SOLVER Optimisers: OPXRQP / SNOPT Departure frm rbit r launcher perfrmances Flyby cnditins Deep Space Maneuvres size and epch Lw Thrust: engines DB, pwer cnstraints, etc. Arrival at fixed state r at celestial bdy Central bdy gravity field, with expansins Gravity f third bdies assumed as mass pints Lw-thrust frces SRP as a Lambertian reflectin mdel Atmspheric drag frces Residual frces

7 1. TRAJECTORY GENERATION - LAUNCHERS LIBRARY (LAULIB) Database with the perfrmance f different launcher vehicles depending n C3 and declinatin f the escape trajectry ELECTRICAL CHEMICAL Departure cnditins ptimisatin t maximise the mass delivered at the target bdy/state

8 1. TRAJECTORY GENERATION EXPLOITATION (1/4) Prjectin f the spacecraft trajectry and the rbit f a number f bdies in different reference frames Time evlutin f distance and distance rates t a number f bdies Time evlutin f a number f angles f interest fr trajectry analysis purpses Time evlutin f the thrust variables and the spacecraft mass Time evlutin f the rbital elements Satellite grund-track n different bdies

9 1. TRAJECTORY GENERATION EXPLOITATION (2/4)

10 1. TRAJECTORY GENERATION EXPLOITATION (3/4)

11 1. TRAJECTORY GENERATION EXPLOITATION (4/4)

12 Range and range rate 2. MEASUREMENTS: GENERATION & EXPLOITATION DOR and ΔDOR frm a number f GS baselines On-bard ptical measurements f celestial bdies On-bard accelermeter measurements On-bard radar measurements f a nearby bject NEW! Feature tracking and landmark measurements NEW! GNSS measurements

13 3. COVARIANCE ANALYSIS WHY THE COVARIANCE ANALYSIS? T calculate theretical accuracy in: 1. knwledge f the spacecraft state 2. further estimatin parameters SRIF Batch filter mixing: a priri inf + assciated dynamics + measurements. 1. deviatin in state vectr estimated at the beginning f the mapping time interval 2. augmented state and cvariance matrix prpagated t next mapping time

14 3. COVARIANCE ANALYSIS - PARTIAL DERIVATIVE Estimatin prcess require t cmpute the PARTIAL DERIVATIVES with respect t the ESTIMATION VARIABLES DYNAMICS OBSERVABLES TRANSITION MATRIX MEASUREMENTS MATRIX Map cvariance int next time interval Update knwledge cvariance matrix

15 3. COVARIANCE ANALYSIS EXPLOITATION BEPICOLOMBO frm Earth departure t Earth SB with Venus FB in between Mapping: every tw days in the lng arcs every 0.25 days fr shrt arcs (planets SOI) Initial uncertainty at Earth launch: Psitin. 10 km Velcity: 1 m/s Mass: 0.1 kg Thrust variables as ECRVs, uncertainty at: 1% 0.6º autcrrelatin time f 1d Residual acceleratin as ECRV f: km/s 2 autcrrelatin time f 1 day Range and range-rate frm GS at: Perth Madrid Range nise at: 10 m randm 2 m bias Range rate at: 0.3 mm/s randm n bias Grund statin psitin errrs: 1 m in X and Y psitin 2 m in Z psitin

16 3. COVARIANCE ANALYSIS EXPLOITATION BEPICOLOMBO frm Earth departure t Earth SB; Venus FB in between

17 WHY THE MONTE CARLO UTILITY? 4. SIMULATION - MONTE CARLO T simulate the navigatin prcess ver a number f cases with randm cnditins. Navigatin prcess is repeated fr all the simulatins, perfrming: 1. Prpagatin f the simulated real wrld and estimated wrld 2. Calculatin f the simulated real wrld measurements and the recnstructed measurements 3. Estimatin f the augmented state vectr at the beginning f each mapping interval 4. Mapping f the estimated state t the end f each interval 5. Perfrmance f the guidance prcess bth fr electrical and chemical prpulsin

18 4. SIMULATION - MONTE CARLO MC fr BEPICOLOMBO n knwledge and dispersin uncertainty in tt psitin

19 4. SIMULATION - MONTE CARLO MC fr BEPICOLOMBO n fuel cnsumptin and final dispersin in the pericentre plane f GAM 2 in Mercury

20 MC fr NEOShield-2: clse apprach phase mixing n-grund and n-bard measurements 4. SIMULATION - MONTE CARLO

21 4. SIMULATION - STATISTICAL ANALYSIS BEPICOLOMBO 1-σ values f the deviatins in the lw-thrust cntrls t meet the final state and distributin f fuel mass cnsumptin

22 5. TRAJECTORY REOPTIMISATION WHY RE-OPTIMISE THE TRAJECTORY? Because the ptimal trajectry changes if we deviate frm the nminal slutin. A full simulatin f the navigatin prcess, with a full navigatin and guidance lp is needed fr each f the shts f the calculatin. Tw different ptins: a) Internal t LOTNAV b) External (i.e. DITAN) On tp n navigatin errrs, implemented failure cases are: Ignitin delay f the prpulsin engine Engine flame-ut Nn-nminal perfrmance f the lw-thrust engine Nn-nminal launch int escape rbit Nn-nminal planetary flyby

23 CONCLUSIONS LOTNAV IS A POWERFUL AND LIVING TOOL A versatile multi-platfrm navigatin & missin analysis tl: t prduce trajectry prfiles f applicatin t navigatin t perfrm quick and thrugh analysis f achievable OD perfrmances t characterise the guidance requirements tgether with the validatin f the OD results Capable t interface with ther reference tls fr missin re-ptimisatin Successfully applied t numerus ESA prjects and in several editins f the GTOC Cntinuusly updated and imprved t expand its capabilities: Nw highly mdularised t integrate different mdules in external simulatrs With SPICE ephemerides available Incrprating features tracking and landmarks navigatin Including GNSS measurements

24 THANK YOU Elecnr Deims Elecnr is the Deims trademark is the encmpassing trademark encmpassing the Elecnr the Grup s Elecnr cmpanies Grup s f cmpanies Aerspace, f Technlgy Aerspace, and Technlgy Infrmatin and Systems: Infrmatin Deims Systems: Space Deims S.L.U. (Tres Space Cants, S.L.U. Madrid, (Tres Cants, Spain), Madrid, Deims Spain), Engenharia S.A. (Lisbn, Prtugal), Deims Castilla La Mancha S.L. (Puertllan, Ciudad Real, Spain), Deims Space UK Ltd. (Harwell, Oxfrd, United Kingdm), Deims Space S.R.L. (Bucharest, Rmania) Deims Engenharia S.A. (Lisbn, Prtugal), Deims Castilla La Mancha S.L.U. (Puertllan, Ciudad Real, Spain), Deims Space UK Ltd. (Harwell, Oxfrd, United Kingdm), Deims Space S.R.L. (Bucharest, Rmania)