Space Systems Engineering

1
Space Systems Engineering
2
Successful Application of New Technologies to the
Rosetta and Mars Express Simulators
J. Martin, R.Lowe J.J.Osborne, S.Thorn, A.
Young, and P.MatakidisVEGA I-T GmbHT2-47
3
Overview

• Introduction
• Simulator Architecture
• Spacecraft Modelling Techniques
• The Emulator Solution
• Generic Payload Modelling
• Conclusions
• Contacts

4
Introduction
5
Rosetta / Mars Express Simulators

• Both are real-time simulators of the Spacecraft
  and Ground segment
• Used for validating the Mission Control System,
  validating Flight Control Procedures and training
  the Flight Control Team
• High fidelity model of Space to Ground link,
  Onboard Data Management functions and Attitude
  Control functions
• Low fidelity (but highly configurable) model of
  Payloads

6
Mandatory New Technologies

• Application of SIMSAT-NT mandatory
• Application of 1750 Emulator technology mandatory
• Application of Simulation Model Portability
  Standards (implemented by the SMI)

7
Influence of New Technologies

• SIMSAT-NT enabled
• Wider use of C/C
• Use of Microsoft COM
• Execution of JavaScript models
• 1750 Emulation enabled
• Execution of real flight software for DMS/AOCMS
• SMI enabled
• Integration of code generated from Graphical
  Modelling techniques
• Separate development of Payload models

8
Development Programme

• Both Rosetta and Mars Express have commonality in
  hardware and software
• Both have fixed launch dates separated by 4
  months
• Shared development between Rosetta and Mars
  Express - one project ROSMEX

9
Simulator Architecture
10
ROSMEX Simulator Architecture
SIMSAT-NT Simulation
Mission Control System
Kernel
MMI
GUI
SMI I/f
Ground Segment Simulation
X-25 Link
SMI I/F
SMI I/F
Satellite Database
TM / TC Handler (XML)
TTC Streams
Global Data and Model Services (C)
Spacecraft Model Code (C)
Payload Models (JavaScript)
Spacecraft Model Code (FORTRAN)
CDMU Model
PCI I/F (Intel)
ROSE-SMI Code Generator
Graphical Modelling Tool (CAE ROSE)
11
ROSMEX Simulator Architecture

• MMI (Man Machine Interface) - This is a windows
  based user interface allowing the visualisation
  and manipulation of the simulator and its data
• Kernel - The real-time simulation kernel controls
  the execution of the simulator models

12
ROSMEX Simulator Architecture

• Simulator Models - These are models that simulate
  the actual spacecraft sub-systems, the
  environment (orbits, planetary data, etc.) and
  the ground equipment
• Spacecraft models - All the main spacecraft
  models are developed using C and a graphical
  modelling tool (CAE ROSE)

13
ROSMEX Simulator Architecture

• Emulator - The model of the processor hardware
  (CDMU) are C. This interfaces via PCI bus to
  the emulation of the 1750 on an Alpha card
• Payload models - The payload models have been
  developed by generating an XML description of
  TC/TM characteristics together with a JavaScript
  template for model functionality directly from
  the spacecraft database

14
Spacecraft Modelling Techniques
15
Graphical Modelling

• Use CAE ROSE for model development and unit test
• Integrate into SIMSAT runtime environment for
  integration and system test
• ROSE generated code is not SMI compatible
• Use an adapter to generate SMI code to publish
  data, event, user command and schedule
  information
• ROSE Model Fortran is re-compiled to run under
  Windows-NT

16
ROSE / SMI Adapter
SIMSAT NT GUI
ROSE
SIMSAT NT Kernel
ROSE-SMI code generator
SMI
Publish Data Service
Event Entry Point
ROSE SMI Adapter
Command Entry Points
Schedule Initialiser
ROSE Model Code
ROSE Global Data
Spacecraft Models
17
Graphical Modelling vs Conventional Modelling

• Graphical Modelling used for
• Network models - RCS
• Switching models - Power, Thermal control
• Hardwired / serial TC and TM
• Advantage is that you can visualise the model
• Conventional Models used for
• CDMU and the Emulator interface
• Data handling bus
• Solid State Mass Memory
• Advantage is that sharing of models from Rosetta
  to MEX is possible with use of compiler switches

18
The Emulator Solution
19
Co-processor Emulator Solution

• Co-processor emulator solution was provided as an
  infrastructure development
• Project specific solutions were required for
• Execution of two emulators on one card
• Implementing block transfers between the
  emulators
• Improving the link from host to card for copying
  breakpoint information
• Forcing changes to the flight software for
  setting failures or for debugging purposes

20
Co-Processor Emulator Integration for ROSMEX
21
Generic Payload Modelling
22
ROSMEX Payload Model Architecture
Spacecraft
Payload
AQUA
SMI
Payload I/F
Power
Thermal
Payload Models
SSMM
TC
Decoder
RTU
TM
Encoder
Spacecraft
Payload Functions (J-Script)
TM/TC
TMTC Handlers (J-Script)
Models
File (XML)
Spacecraft
Satellite Database
23
Modelling Concept

• Use AQUA infrastructure developed by VEGA for
  payload models of the NASA AQUA mission
• Provides generic TM encoder and TC decoder
  functions
• Initialisation is via description in XML file
• Data exchange to spacecraft simulator models is
  via SMI
• Payload functionality is written as JavaScript
• Payload TC/TM functions and model data also
  published to SMI by running JavaScript

24
Model Generation

• Satellite Database used to generate payload model
  information
• XML file generated automatically
• TC/TM function declarations to SMI generated
  automatically (JavaScript)
• Payload functions templates generated
  automatically (Placeholders in generated
  JavaScript is later manually edited)

25
Advantages

• Clean SMI interface allows payload model
  development to be isolated from rest of the
  spacecraft (using a low spec. PC)
• Use of JavaScript allows payload model functions
  to be modified and re-loaded to the simulation
  without the need for re-compilation
• Automation of generation from the satellite
  database allows rapid development of basic models
  and enables quick update to new satellite
  databases

26
Conclusions
27
Conclusions

• Huge step forward in technology for ROSMEX
• First ESOC operational simulator to use SIMSAT-NT
  and benefit from other Windows technology running
  on Intel
• First ESOC simulator to adopt Simulator Model
  Portability Standard implementation
• First to use features of XML

28
Putting the new technology into perpective