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New Software Technology in Space: BOSS -- a Dependable Open
Source Embedded Operating System
Sergio Montenegro
Fraunhofer-Institut für Rechnerarchitektur und Softwaretechnik
FIRST
BOSS targets a principle which the world forgot a long time ago:
Simplicity. We created an embedded real time operating system for
safety critical applications, for example Satellite control and
medical devices. Our experience shows: the first enemy of safety is
the complexity. If you need safety use only what you can clear
understand. This was the philosophy creating BOSS. First: build
every thing as simple as possible. Second: use modern framework
technology to reduce the complexity of the applications. Third: use
component technology to be able to handle the remaining complexity.
The result is very promising. BOSS is already working in space
(Satellite BIRD) in medical devices and other mission critical
systems for years without interruptions. And even complex
functionality can be implemented very easily using BOSS.
BOSS was designed as a frame work to be a dependable real time
embedded operating system which can be easily certified by different
organisations. Due to the fact, that complexity is the first foe of
safety, BOSS is intended to be as simple as possible, so it is
easier to understand, to review, to use etc. The whole kernel can be
printed in a few pages. Some parts of BOSS are being verified
mathematically and formally using model checker and theorem
proofers. With the current state of the art on formal verification,
complex systems cannot be verified formally, but BOSS can be. BOSS
is based on very few and simple basic functions, which can be
proofed very faithfully, and these functions are used for almost
every operation of the kernel.
An example: Satellite BIRD
Small satellites have to meet a big challenge: to answer high
performance requirements by means of small equipment and especially
of small budgets. Out of all aspects the cost aspect is one of the
most important driver for small satellite missions. To keep the
costs within the low-budget frame the demonstration of new and not
space-qualified technologies for the spacecraft is one key point in
fulfilling high performance mission requirements. Taking this into
account the DLR micro-satellite mission BIRD (Bi-spectral Infra-Red
Detection) has to demonstrate a high performance capability of
spacecraft bus by using and testing new technologies including
modern software technology. The control system of bird relays on
the framework real time operating system BOSS. The spacecraft bus is
controlled by the dependable board computer . To achieve a high
dependability, safety, and lifetime, the board computer is formed of
four identical computers. The redundant nodes and all the devices of
the satellite that have to be controlled by the board computer are
interconnected by several bus systems with different protocols.
Zusätzliche Links: Slides
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