Towards the definition of
ESA’s future OBCP building block
M. Ferraguto, J. Johansson, K. Jurva (SSF)
A. Oganessian, M. Prochazka (ESA)
A.I. Rodríguez , T. Schoofs (GMV)
M. Barrenscheen (IDA), M. Muñoz (SA), M. Cupak (ESC)
16.05.2012
DASIA 2012 Conference
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Agenda
• Motivation and objectives
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Review of existing OBCP implementations
Assessment of the ECSS OBCP standard
Assessment of potential innovations
Requirements and interfaces of the OBCP building block
OBCP building block prototype
Conclusions
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DASIA 2012 Conference
What is an On-Board Control Procedure (OBCP)?
• Definition:
A procedure to be executed on-board…
…which can easily be loaded, executed, and replaced…
…without modifying the remainder of the on-board SW
• Main use cases:
• Satellite operations
• Implementation of system/mission functionality
• Testing
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What is an On-Board Control Procedure (OBCP)?
• It is like having an automatic operator on-board:
• Send sequences of commands
• Optionally including:
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Execution logic
Checking command results
Perform (complex) monitoring tasks
React on events
• Different implementations on several ESA
missions over the last 25 years
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Motivation and objectives
• Starting points:
• New ECSS standard on OBCP ECSS-E-ST-70-01C
• OBCP system
• Development lifecycle for OBCPs
• Relationship to spacecraft on-board software
lifecycle
• SAVOIR-FAIRE: on-board SW reference architecture
• Based on building blocks
• Objective:
• Define the requirements and interfaces for a reusable
and standard flight-qualified OBCP SW system building
block.
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Two parallel activities: objectives
• Define the OBCP building block, including
• Provided and required interfaces
• Its position within the ESA OBSW reference
architecture defined in SAVOIR-FAIRE
• Provide a vision of the future use of OBCPs
• Set of use cases and to consider options for further
steps in the standardisation of OBCPs, such us
updating the current OBCP standard or standardising
the OBCP language.
• The two parallel activities are currently on-going
and they are planned to conclude in 2012
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Two parallel activities lead by ESA
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Agenda
• Motivation and objectives
• Review of existing OBCP implementations
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Assessment of the ECSS OBCP standard
Assessment of potential innovations
Requirements and interfaces of the OBCP building block
OBCP building block prototype
Conclusions
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Review of Existing OBCP Implementations
• The available documentation for a number of
different OBCP implementations has been
reviewed
• Herschel-Planck, GOCE, Sentinel-1, Cryosat-1, Rosetta,
Venus Express, BepiColombo, Columbus and the NASA
VML system
• The level of detail of the available documentation
varies greatly
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Two broad classes of OBCP systems exist
• Command sequences
• An OBCP is a sequence of telecommands on a relative
time-line
• Limited (if any) execution logic
• Similar to ground operations, but permanently resident
on-board
• More suitable for the implementation of fixed operations
sequences
• Script-like
• Written using a high-level language, possibly compiled,
and executed on-board by an on-board interpreter
• More suitable to implement complex control logic
• Requires a more complex OBCP engine
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Existing Implementations: main aspects assessed
• Language capabilities
• E.g. fixed TC tokens vs general-purpose language + library
• OBCP preparation environment capabilities
• E.g. compiler, debugger, link to system DB, etc.
• OBCP execution environment capabilities
• E.g. commandability, observability, scheduling, etc.
• OBCP management capabilities
• E.g. relationship with the OBSW lifecycle
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Agenda
• Motivation and objectives
• Review of existing OBCP implementations
• Assessment of the ECSS OBCP standard
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Assessment of potential innovations
Requirements and interfaces of the OBCP building block
OBCP building block prototype
Conclusions
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Assessment of the ECSS OBCP standard
• Goals:
• Considerations of further standardisation steps
• Propose a possible update of the current standard
• Improve understanding of the standard and trigger a
discussion leading to the definition of the OBCP
building block
• Approach:
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Look at use cases, existing and future missions
Analyse the standard
Find inconsistencies and ambiguities
Propose improvements
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Assessment of the ECSS OBCP standard
• The standard introduces a number of concepts
like
• OBAP (On-Board Application Procedures) vs. OBOP
(On-Board Operations Procedures)
• and covers all the main aspects of OBCPs, including:
• Use cases
• Language capabilities
• Preparation environment capabilities
• Execution environment capabilities
• Engineering process, taking into account the
distinction of OBOPs vs. OBAPs
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Identified possible improvements of the standard
• Prioritisation of the requirements, taking into
account:
• The needs of the various users
• OBCP execution environment as a black box to be
integrated into the host OBSW
• Mandatory vs optional requirements
• Standardisation of the language, not only of the
language features
• Some requirements could be removed: e.g. the ones
on the OBCP viewer
• Better characterisation of OBOP vs OBAP
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Agenda
• Motivation and objectives
• Review of existing OBCP implementations
• Assessment of the ECSS OBCP standard
• Assessment of potential innovations
• Requirements and interfaces of the OBCP building block
• OBCP building block prototype
• Conclusions
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Assessment of potential innovations
• Started from taking the “best of”
• Additional concepts like:
• Explicit support of state machines
• Standardisation of the target “object code” language
• Source language improvement to better support the
users, e.g. support of at least basic forms of objectorientation
• Standardised interface towards the system database
• Integration with the SAVOIR-FAIRE standard on-board
SW architecture
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Further innovations related to OBSW trends
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Time and Space Partitioning [TSP]
SOIS architecture [SOIS]
Component-oriented frameworks [CBSE]
Relation to FDIR (Fault Detection Isolation and
Recovery)
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Agenda
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Motivation and objectives
Review of existing OBCP implementations
Assessment of the ECSS OBCP standard
Assessment of potential innovations
• Requirements and interfaces of the OBCP
building block
• OBCP building block prototype
• Conclusions
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DASIA 2012 Conference
Requirements and interfaces of the OBCP building block
• Requirements definition
• Based on the OBCP ECSS standard
• Accompanied with use cases to demonstrate their
purpose
• Compatible with the ESA OBSW reference architecture
• Taking into account the current OBCP implementations
• Provided and required interfaces and interaction
to flight software and spacecraft operations
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DASIA 2012 Conference
Agenda
•
•
•
•
•
Motivation and objectives
Review of existing OBCP implementations
Assessment of the ECSS OBCP standard
Assessment of potential innovations
Requirements and interfaces of the OBCP building block
• OBCP building block prototype
• Conclusions
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OBCP building block prototype
• The prototype activity is on-going
• Demonstration of main:
• Requirements
• Interfaces
• Innovations
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SSF building block prototype experience
• Starting from the very advanced OBCP system
used for the Herschel-Planck
• Focuses on implementation and demonstrations
of new concepts like:
• Explicit support for state machines to facilitate OBCP
design and implementation
• Use of a priority system avoiding starvation of lowerpriority OBCPs in a way that is transparent for the
higher-priority ones
• Basic forms of object-orientation
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GMV building block prototype experience (i)
• At present, the specification of requirements and
interfaces is progressing considering current
ECSS-E-ST-70-11 standard specification.
• Assessment of ECSS-E-ST-70-11 requirements in
categories: core an optional requirements
• Proposal for new requirements coming from our
research in future use of OBCPs
• The high level architecture that is proposed is in
line with the COrDeT OBSW Reference
architecture, [COrDeT]
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GMV building block prototype experience (ii)
• Some core functionalitis are selected to be
prototyped and modelled by using COrDeT
toolset framework
• OBCP-BB Interaction Layer
• Une of TASTE framework
• Prototyping a Lua interpreter implementing the
OBCP-Engine
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DASIA 2012 Conference
Agenda
•
•
•
•
•
•
Motivation and objectives
Review of existing OBCP implementations
Assessment of the ECSS OBCP standard
Assessment of potential innovations
Requirements and interfaces of the OBCP building block
OBCP building block prototype
• Conclusions
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Conclusions
• Proposed a number of improvement and innovations
in the OBCP domain
• Requirements and interfaces for a future standard
on-board SW OBCP building block
• Two prototype implementations (on-going)
• Future work:
• Consolidation of results (requirements and interfaces),
focusing on OBOPs (reflecting operator's needs) and
OBAPs (reflecting software system needs)
• In the long term: implementation of a pre-qualified
building block, to be made available for future space
missions
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Thanks for your attention
Any question?
Contact:
[email protected]