STRAST. UPMSat-2 On-board computers. Grupo de Sistemas de Tiempo Real y Arquitectura de Servicios Telemáticos Universidad Politécnica de Madrid.

Size: px

Start display at page:

Download "STRAST. UPMSat-2 On-board computers. Grupo de Sistemas de Tiempo Real y Arquitectura de Servicios Telemáticos Universidad Politécnica de Madrid."

Ethelbert Burke
5 years ago
Views:

1 On-board computers Grupo de Sistemas de Tiempo Real y Arquitectura de Servicios Telemáticos Universidad Politécnica de Madrid dit UPM

2 Computers in spacecraft Computers are used on board of spacecraft for a variety of functions, e.g. computing attitude and orbit control algorithms (AOCS) performing other platform control functions processing and storing data for various subsystems handling communications with the ground segment telecommand (TC) / telemetry (TM) handling payload data and ground communications Depending on the size and complexity of the spacecraft these functions may be allocated to one or more on-board computers (OBC) 2011 grupo 2

3 Centralized vs de-centralized architecture sensors TMC OBC actuators other subsystems TMC OBC sensors system bus other subsystems actuators 2011 grupo 3

Computer hardware Environment conditions restrict applicable technology radiation may cause damage to electronic circuits limited power availability CPU and memory technology slower than

4 Computer hardware Environment conditions restrict applicable technology radiation may cause damage to electronic circuits limited power availability CPU and memory technology slower than state-of-the-art ESA has qualified the LEON processor family based on the SPARC v8 32 bit RISC architecture open-source VHDL model available under GPL speed 100 MHz, power 1 W Computers are connected to other subsystems via high-speed data links serial buses: SpaceWire, CAN bus, MIL1553B 2011 grupo 4

5 Computer software Many critical functions depend on software high-integrity requirements Most software functions have real-time requirements have to be carried out within specific time intervals Verification & validation process is crucial safety management Technology choice driven by high-integrity requirements e.g. Ada, RTOS, static analysis, temporal analysis Standards: ECSS-E-ST-40-C / ECSS-Q-ST-80-C specify software development process depending on criticality level 2011 grupo 5

6 Ada Programming language for high-integrity, large embedded systems developed under US DoD contract starting in 1973 the current version is Ada 2005 Strong support for concurrency and real-time concurrent tasks, shared data objects Support for mixed-language programming standard interfaces to C and other languages Used in critical software domains aeronautics, railways, nuclear plants, space Ravenscar profile: tasking subset for high-integrity systems 2011 grupo 6

7 Open Ravenscar Kernel (ORK) Real-time tasking kernel supporting the Ada Ravenscar profile running on LEON2-3 bare-board computers no underlying RTOS needed Supports concurrent threads of execution (Ada tasks) communication by means of shared data objects with mutually exclusive access Predictable scheduling and communication real-time properties can be analysed and proved correct Careful, reliable design 2011 grupo 7

8 Cross-compilation chain source files compiler object files linker RTS sources RTS binaries Development platform (Linux workstation) debugger simulator executable file Target platform (LEON-based computer) monitor loaded program 2011 grupo 8

9 TASTE A toolset for generating on-board real-time code from high-level models Integrated with timing analysis tools functional view Ada C interface view AADL deployment view AADL model transformation tool AADL concurrency view Ocarina Ada C implementation code 2011 grupo 9

10 Example toy_example 10 ms TMTC TC BOOST_ORDER POS 100 ms GNC POS read update TC_POS 20ms PRO BOOST_ORDER 2011 grupo 10

11 Software development & validation facilities DEIMOS Space S.L.U., grupo 11

12 Testing facilities tsat schematic DEIMOS Space S.L.U., grupo 12

13 Acronyms AOCS Attitude and orbit control system GPL GNU public license OBC On-board computer OBDH On-board data handling ORK Open Ravenscar real-time kernel RTOS Real-time operating system TC Telecommand TM Telemetry TMC Telemetry and telecommand subsystem VHDL Very high speed integrated circuit hardware description language 2011 grupo 13

Ensuring Schedulability of Spacecraft Flight Software

Ensuring Schedulability of Spacecraft Flight Software Flight Software Workshop 7-9 November 2012 Marek Prochazka & Jorge Lopez Trescastro European Space Agency OUTLINE Introduction Current approach to