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Body Text,Second Level,Third Level,Fourth Level,Fifth Level,EGOS 2005,Darmstadt,Germany,8,th,10,th,November,2005,dataspazio,Operational constellation simulation with on-board processor emulation,*,Operational constellation simulation with on-board processor emulation,F.Tartara,Dataspazio,Via S.Cannizzaro 71 00156 Rome,Italy,fabio.tartaradataspazio.it,Introduction,This presentation describes,a hardware and software architecture,designed and used by,Dataspazio,for simulation of LEO/MEO/GEO satellite constellations.,Satellite constellations,constitute a very common reality,in the world.Well known constellations are,for example GPS,GLONASS,Iridium,and,in a near future,Galileo.,For constellations,processing requirements are even more demanding,due to multiple satellites to be simulated and multiple emulations.In addition,the different satellite simulations have to be coordinated.,The presented approach solves these issues,allowing a real-time TM/TC simulation with on-board processor emulation and with variable number of satellites.,Satellite s,imulation is,a very,complex,task,and requires high computational power,especially when processor emulators are used in the simulation.,Constellation Simulation Features,Typical features of single satellite simulation will be necessary also for constellation(real time,high fidelity TM/TC,Flight SW emulation,configurability).,The real-time requirement for a constellation simulator implies,usage of multiple workstations,therefore we also need:,synchronised,constellation simulation:the different satellites simulations must be executed in a coordinated manner(e.g.start,stop,run,save/restore state),integrated monitor and control,of the constellation simulation:the operator must have appropriate means to monitor and control the constellation simulation from a single workstation(e.g.scenario definition and displays at constellation level,logging),Purpose of satellite simulation is mainly for training and Control Centre validation.,The Single Satellite Approach(HW),High-performance,Workstation,or PC(MMI+,models,),LAN,for,Control,Centre,connection,The Single Satellite Approach(SW),All components run on the high performance Workstation,Constellation Simulator HW Architecture,Constellation Simulator,HW Architecture Key Features,Two workstation classes:Control WS and Simulation WS,Distributed architecture:one simulated satellite on each Simulation WS=the high processing load due to multiple OBSW emulations is reduced to acceptable limits,High simulation integration:the additional Control WS is the MMI for centralised and integrated Monitor and Control by a single Operator,Excellent modularity:add/remove satellites by adding/removing Simulation Workstations,Optimised network traffic due to the double LAN solution:TM/TC data only are routed to the Control Centre LAN by the Control WS.Sync/Sim data are not routed.,Constellation Simulator SW Architecture,SW Architecture Key Features,Evolution of Dataspazio single-satellite infrastructure/models,successfully used for SAX,SICRAL,Atlantic Bird 1 satellite simulators,Simulation Kernel(see Single Satellite Approach)split in two parts:1 Master and N Slaves,Master Kernel:implements Slave Kernels synchronisation and centralisation,acts as Simulator MMI server,Slave Kernels:are slaves of Master Kernel,interfacing models for Operator commands execution and data retrieval,Ground Models run on Control WS,no additional load on satellite simulations,Satellite Models Architecture,Satellite Models Details,Satellite models:as for the classic single satellite case,they implement the behaviour of the on-board subsystems(TTC,Power,Thermal,Payload,Sensors,Actuators,etc.)and the Environment/Attitude Dynamics,On-board computer model:the ESOC ERC-32 emulator(for Alpha processor)has been used+models of the surrounding OBC and bus HW devices,Alpha processor ensures high performances for emulation,since the ESOC emulator core is automatically generated in Alpha assembler language,SMI layer for Simulation Model Portability compliance,Two main issues:due to the different address spaces,both scheduling and data access require dedicated mechanisms,Model Scheduling,Two choices were possible for model scheduling:one Scheduler(on Master Kernel)or multiple Schedulers(on Slave Kernels),Normally,models require scheduling frequency between 1 Hz and 10 Hz,Emulated on-board computer requires an activation rate of 512 Hz or even more,The multiple Schedulers approach has been chosen to avoid performance problems due to network delays and collisions,Presence of multiple Schedulers requires a synchronisation mechanism between Master and Slave Kernel,Master-Slave Kernel Synchronisation,LAN,Control Workstation,Simulation Workstation 1 N,time,M,K,S,K,Satellite Models,S,K,M,K,.IDLE.,M,K,Simulation Cycle Interval(SCI),Simulation Elapsed Time(SET),RUN message,Activation,END,SYNC message,RUN message,Key,MK Master Kernel,SK Slave Kernel,Master-Slave Kernel Protocol,Synchronisation and sched
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