58 lines
4.1 KiB
Markdown
58 lines
4.1 KiB
Markdown
|
# Framework Design
|
||
|
|
|
||
|
|
Satellites and space systems in general are complex systems with a wide range of requirements for
|
||
|
|
both the hardware and the software.
|
||
|
|
Consequently, the general design of the framework is centered around many light-weight components
|
||
|
|
which try to impose as few restrictions as possible on how to solve certain problems.
|
||
|
|
|
||
|
|
There are still a lot of common patterns and architectures across these systems where guidance
|
||
|
|
of how to solve a problem and a common structure would still be extremely useful to avoid pitfalls
|
||
|
|
which were already solved and to avoid boilerplate code. This framework tries to provide this
|
||
|
|
structure and guidance the following way:
|
||
|
|
|
||
|
|
1. Providing this book which explains the architecture and design patterns in respect to common
|
||
|
|
issues and requirements of space systems.
|
||
|
|
2. Providing an example application. Space systems still commonly have large monolithic
|
||
|
|
primary On-Board Softwares, so the choice was made to provide one example software which
|
||
|
|
contains the various features provided by sat-rs.
|
||
|
|
3. Providing a good test suite. This includes both unittests and integration tests. The integration
|
||
|
|
tests can also serve as smaller usage examples than the large `satrs-example` application.
|
||
|
|
|
||
|
|
This framework has special support for standards used in the space industry. This especially
|
||
|
|
includes standards provided by Consultative Committee for Space Data Systems (CCSDS) and European
|
||
|
|
Cooperation for Space Standardization (ECSS). It does not enforce using any of those standards,
|
||
|
|
but it is always recommended to use some sort of standard for interoperability.
|
||
|
|
|
||
|
|
A lot of the modules and design considerations are based on the Flight Software Framework (FSFW).
|
||
|
|
The FSFW has its own [documentation](https://documentation.irs.uni-stuttgart.de/fsfw/), which
|
||
|
|
will be referred to when applicable. The FSFW was developed over a period of 10 years for the
|
||
|
|
Flying Laptop Project by the University of Stuttgart with Airbus Defence and Space GmbH.
|
||
|
|
It has flight heritage through the 2 mssions [FLP](https://www.irs.uni-stuttgart.de/en/research/satellitetechnology-and-instruments/smallsatelliteprogram/flying-laptop/)
|
||
|
|
and [EIVE](https://www.irs.uni-stuttgart.de/en/research/satellitetechnology-and-instruments/smallsatelliteprogram/EIVE/).
|
||
|
|
Therefore, a lot of the design concepts were ported more or less unchanged to the `sat-rs`
|
||
|
|
framework.
|
||
|
|
FLP is a medium-size small satellite with a higher budget and longer development time than EIVE,
|
||
|
|
which allowed to build a highly reliable system while EIVE is a smaller 6U+ cubesat which had a
|
||
|
|
shorter development cycle and was built using cheaper COTS components. This framework also tries
|
||
|
|
to accumulate the knowledge of developing the OBSW and operating the satellite for both these
|
||
|
|
different systems and provide a solution for a wider range of small satellite systems.
|
||
|
|
|
||
|
|
`sat-rs` can be seen as a modern port of the FSFW which uses common principles of software
|
||
|
|
engineering to provide a reliable and robust basis for space On-Board Software. The choice
|
||
|
|
of using the Rust programming language was made for the following reasons:
|
||
|
|
|
||
|
|
1. Rust has safety guarantees which are a perfect fit for space systems which generally have high
|
||
|
|
robustness and reliablity guarantees.
|
||
|
|
2. Rust is suitable for embedded systems. It can also be run on smaller embedded systems like the
|
||
|
|
STM32 which have also become common in the space sector. All space systems are embedded systems,
|
||
|
|
which makes using large languages like Python challenging even for OBCs with more performance.
|
||
|
|
3. Rust has support for linking C APIs through its excellent FFI support. This is especially
|
||
|
|
important because many vendor provided libaries are still C based.
|
||
|
|
4. Modern tooling like a package managers and various development helper, which can further reduce
|
||
|
|
development cycles for space systems. `cargo` provides tools like auto-formatters and linters
|
||
|
|
which can immediately ensure a high software quality throughout each development cycle.
|
||
|
|
5. A large ecosystem with excellent libraries which also leverages the excellent tooling provided
|
||
|
|
previously. Integrating these libraries is a lot easier compared to languages like C/C++ where
|
||
|
|
there is still no standardized way to use packages.
|
||
|
|
|