Experiences from the SISO SpaceFOM at the European Space Agency

The Harwell Robotic and Autonomy Facility (HRAF) activities funded by the European Space Agency (ESA) aim to provide advanced capabilities to support the development and testing of complex autonomous systems for the exploration of our Solar System. The outcome of one of these activities is a a flexible simulation environment allowing models and real hardware to be combined, compared and tested in a plug and play mode.

HRAF has carried out three pilot studies on the use of simulation concepts. This paper presents experiences from Pilot 3, in particular from the task of developing a Federation specialized for space exploration scenarios.

The first scenario is concerned with Mars Sample Return (MSR). Specifically, the mission phase where the Orbiting Sample (OS) is retrieved by a Chaser spacecraft (ERO) in Mars orbit for later return and analysis on Earth. The guidance, navigation and control (GNC) functionality using Image based Navigation techniques is accompanied by a high-fidelity Physics “real-world” simulator. The second scenario is concerned with the soft, precision landing of a Spacecraft on a low gravity Near Earth Object (NEO). 

The federation is based on the generic standard for distributed simulation: High Level Architecture (HLA IEEE 1516-2010), together with the associated SISO Space Reference FOM standard (SISO-STD-018 “SpaceFOM”). Different configurations of the Federation are constructed, the MSR Scenario considering a Model-in-the-Loop (MIL) and Hardware-in-the-Loop (HIL) configuration and the NEO Scenario implementing MIL, Processor-in-the-Loop (PIL) including Synthetic Image generation and HIL configurations. In many cases the same functionality is provided as MIL, PIL and HIL and federates can be exchanged between executions. The federation can also be run locally or distributed between ESA and contractor sites. 

Authors: Björn Möller, Tom Gray, Steven Kay, Aron Kisdi, Karl Buckely, Juan Delfa
Publication: Proceedings of 2021 Virtual Simulation Innovation Workshop, 2021-SIW-018, Simulation Interoperability Standards Organization, February 2021

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Security in Simulation – New Authorization Opportunities in HLA 4

A new version of the High Level Architecture (HLA), with the working name HLA 4, is under development. One security aspect that this new version addresses is authorization. The current version of HLA provides no standardized way to control which federates are allowed in a federation. HLA 4 adds new functionality for authorization, enabling control of which federates are allowed to connect to a Runtime Infrastructure (RTI) and to join a particular federation.

The new functionality is provided using a flexible plug-in design. Many types of authentication can be supported, for example passwords, X.509 certificates, and connection to Active/Open Directory servers. This paper describes a number of use cases for authentication in HLA federations. It also describes the technical design of the new security plug-in. Finally, it discusses the potential and limitations of the selected approach.

Authors: Björn Möller, Mikael Karlsson, Reinhard Herzog, Doug Wood
Publication: Proceedings of 2021 Virtual Simulation Innovation Workshop, 2021-SIW-013, Simulation Interoperability Standards Organization, February 2021

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STANREC 4800 – AMSP-04 NATO Education and Training Network Federation Agreement and FOM Design


Efficient and effective use of NATO and national Modelling & Simulation (M&S) capabilities requires standards for networking and simulation interoperability. The NETN FAFD is a NATO standard recommendation (STANREC 4800) how to represent shared data in distributed simulation environments where M&S services (federates) are connected and federated using the NATO mandated High-Level Architecture standard (STANAG 4603).

In March 2018, the NATO Education and Training Network Federation Agreement and FOM Design (NETN FAFD) document was released as the Allied Modelling and Simulation Publication (AMSP-04) covered by NATO STANREC 4800. This release can be considered the culmination of work, related to Federated Simulation Architecture and Design, conducted over a series of NATO Research Task Groups from MSG-027 starting in June 2003, MSG-052, MSG-068, MSG-106 until MSG-134 ending in December 2017. Although this version of the NETN FAFD is a major milestone, the work continues and the standard evolves based on feedback, new requirements, new concepts, new technologies and updated standards.

This paper describes the background & purpose of NETN FAFD, its current modules and rationale for each, examples of use in major exercises such as Viking, and finally a description of what is going on right now in MSG-163 with evolving the standard and some ideas on what we can expect in future versions of the standard.

Authors: Björn Löfstrand
Publication: STANREC 4800 – AMSP-04 NATO Education and Training Network Federation Agreement and FOM Design. STO-MP-MSG-159-12. MSG-159 Symposium on Symposium on Multinational Interoperability, NATO Modelling and Simulation Group. Ottawa, Canada. October 2018.

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Evolution of NATO standards for federated simulation

Abstract: NATO and the Nations regularly use distributed simulation based on the High Level Architecture (HLA) interoperability standard. The current release is IEEE 1516-2010. In the NATO context, several official documents are available to standardize the use of HLA across NATO Nations:
• STANAG-4603 describing the HLA standard.
• STANREC-4800 describing the NATO Education Training Network (NETN) Federation Object Model and the associated Federation Architecture and FOM Design (FAFD).

The NATO Modelling and Simulation Group (NMSG) has a close relationship and a Technical Agreement with the Simulation Interoperability Standards Organization (SISO) with respect to Simulation Interoperability Standards and has provided significant input to SISO standards development over the last years. E.g. NMSG Task Groups MSG-068 and MSG-106 provided significant input on the modularization of RPR-FOM v2.0, and other Task Groups have provided significant input on C-BML, MSDL and UCATT SISO standards. NATO is also a user of SISO developed standards including IEEE 1516 (HLA) series of standards which is covered in STANAG 4603.

SISO and NATO standards have successfully been applied in developing Federated Simulations to support Education, Training, Exercise and Evaluation. For example, the Swedish Viking Exercises are based on Federated Simulation using STANAG 4603 and NETN FAFD. Other NMSG Task Groups apply the SISO and NATO standards to support different aspects of M&S, e.g. Task Group MSG-147 is developing NETN FAFD FOM modules for Crisis Management and Disaster Response, MSG-164 is developing the concept of Modeling & Simulation as a Service (MSaaS) to manage Federated Simulation etc.

There is a continued need for NATO to experiment with, update and further evolve NATO Standards for Federated Simulation to meet new and evolving simulation interoperability requirements and to harmonize with new and evolving SISO standards.

The objective of the recently (2018) started Task Group MSG-163 similarly named “Evolution of NATO Standards for Federated Simulation” is to further evolve the NATO standards for Federated Simulation. This includes:
• An update of the NATO NETN FOM modules and associated Federation Architecture.
• An update of the NATO reference documents regarding HLA (STANAG, STANREC and AMSP, etc.).

• The definition and implementation of a NATO Certification Service for simulator system interoperability.
• The improvement of the NATO HLA Certification Service. This service covers process, organization and a supporting open source tool (Integration, Verification and Certification Tool, IVCT).
This paper provides an overview of Task Group MSG-163 and presents the preliminary results.

Authors: Björn Löfstrand, Reinhard Herzog, Tobias Kuhn, Horst Behner, Tom van den Berg
Publication: Evolution of NATO standards for federated simulation. SISO-20W-025. Simulation Innovation Workshop, Simulation Interoperability Standards Organizations. Orlando, Florida, February 2020.

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Enhancing Simulation Composability and Reuse with Modular FOMs

Simulation composability and reuse have long represented the “Holy Grail” of distributed simulation. The ability to develop simulation components in a way that enables them to be reused as well as the ability to pull together independently developed simulation components have long promised flexibility and cost savings for Department of Defense simulations.

While the High Level Architecture (HLA) has provided an interoperability standard enabling simulation components to work together, seamless simulation component reuse and composability remain elusive goals. A number of challenges to composability have been identified, and one of the major challenges has always been the data exchange model. Davis [1] and Henninger [2] both address improving composability, and both identify data exchange models as an issue. The Live Virtual Constructive Architecture Roadmap (LVCAR) study [2] recommended standardized common object model components as the highest priority investment for the Department of Defense (DoD) simulation roadmap. Efforts such as the Realtime Platform Reference (RPR) and Space Federation Object Model (FOM) seek to standardize a FOM for a particular community. The Medical Modeling and Simulation (MMS) FOM is expected to do the same for the Medical modeling and simulation community. Modular FOMs are a critical component to improve simulation composability and reuse.

This paper addresses how the Joint Evacuation and Transport Simulation (JETS) system architecture is developing a suite of MMS FOM modules, providing the ability to more easily combine simulation components in various configurations or scale to meet current and future medical training needs.

Authors: Dannie Cutts, Damon Curry
Publication: Proceedings of 2020 Winter Simulation Innovation Workshop, 2020-SIW-013, Simulation Interoperability Standards Organization, February 202

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SISO Space Reference FOM – Tools and Testing

The Simulation Interoperability Standards Organization (SISO) Space Reference Federation Object Model (SpaceFOM) version 1.0 is nearing completion. Earlier papers have described the use of the High Level Architecture (HLA) in Space simulation as well as technical aspects of the SpaceFOM. This paper takes a look at different SpaceFOM tools and how they were used during the development and testing of the standard.

The first organizations to develop SpaceFOM-compliant federates for SpaceFOM development and testing were NASA’s Johnson Space Center (JSC), the University of Calabria (UNICAL), and Pitch Technologies.

JSC is one of NASA’s lead centers for human space flight. Much of the core distributed simulation technology development, specifically associated with the SpaceFOM, is done by the NASA Exploration Systems Simulations (NExSyS) team. One of NASA’s principal simulation development tools is the Trick Simulation Environment. NASA’s NExSyS team has been modifying and using Trick and TrickHLA to help develop and test the SpaceFOM.

The System Modeling And Simulation Hub Laboratory (SMASH-Lab) at UNICAL has developed the Simulation Exploration Experience (SEE) HLA Starter kit, that has been used by most SEE teams involved in the distributed simulation of a Moon base. It is particularly useful for the development of federates that are compatible with the SpaceFOM. The HLA Starter Kit is a Java based tool that provides a well-structured framework to simplify the formulation, generation, and execution of SpaceFOM-compliant federates.

Pitch Technologies, a company specializing in distributed simulation, is utilizing a number of their existing HLA tools to support development and testing of the SpaceFOM. In addition to the existing tools, Pitch has developed a few SpaceFOM specific federates: Space Master for managing the initialization, execution and pacing of any SpaceFOM federation; EarthEnvironment, a simple Root Reference Publisher; and Space Monitor, a graphical tool for monitoring reference frames and physical entities.
Early testing of the SpaceFOM was carried out in the SEE university outreach program, initiated in SISO. Students were given a subset of the FOM, that was later extended. Sample federates were developed and frameworks were developed or adapted to the early FOM versions.

As drafts of the standard matured, testing was performed using federates from government, industry, and academia. By mixing federates developed by different teams the standard could be tested with respect to functional correctness, robustness and clarity.

These frameworks and federates have been useful when testing and verifying the design of the standard. In addition to this, they have since formed a starting point for developing SpaceFOM-compliant federations in several projects, for example for NASA, ESA as well as SEE.

Authors: Björn Möller, Andreas Rydell, Edwin Z Crues, Dan Dexter, Alberto Falcone, Afredo Garro
Publication: Proceedings of 2020 Winter Simulation Innovation Workshop, 2020-SIW-027, Simulation Interoperability Standards Organization, February 2020

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An Update on RPR FOM 3

The purpose of the SISO Real-time Platform Reference FOM (RPR FOM) version 3 is to support real-time platform simulation, matching the capabilities of DIS 7. It will also address some issues in RPR FOM 2. RPR FOM 3 is expected to be completed during 2020. Experimental versions of several FOM modules already exist. This paper summarizes the current status, new and improved capabilities and provides some background and rationale.

Some of the key new features relate to IFF (Identification Friend or Foe), Directed Energy Fire, Information Operations and Entity Appearance and Capabilities. For IFF, Mode 5 and Mode S are the most important additions. The IFF module has also been restructured to better represent the different modes of transponders and interrogators as well as the Interactive Mode. The new Information Operations module is very generic, using two interactions with an extendable set of Actions and Statuses and is expected to be useful for operations like electronic warfare, computer network operations, psychological operations, military deception, and operations security. For Entity Appearance and Entity Capabilities, a number of missing properties have been added, based both on DIS 6 and DIS 7.

One of the challenges in the FOM design is the DIS Attribute PDU, the question if or how to bridge the different basic principles for extending an information model in DIS versus HLA. Another challenge is the principles for transferring ownership. The representation of time stamps is yet another challenge, in particular for pure HLA federations, needing to use Time Management. This paper summarizes the approach taken, including pros and cons.

RPR FOM 3 will be a valuable step forward, particularly for use in federations that mix HLA and DIS based systems, as a migration path from DIS to HLA and as a starting point for further extension.

Authors: Björn Möller, Aaron Dubois, René Verhage
Publication: Proceedings of 2020 Winter Simulation Innovation Workshop, 2020-SIW-028, Simulation Interoperability Standards Organization, February 2020

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Developing Space FOM Federation Agreements


Authors: Björn Möller
Publication: Presentation only, Proceedings of 2019 Winter Simulation Innovation Workshop, 2019-SIW-024, Simulation Interoperability Standards Organization, February 2019

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New Object Modeling Opportunities in HLA 4

One of the main success factors of HLA is that it makes it easy to create, maintain and share federation object models (FOM) for distributed simulations. Such models can be developed and extended for almost any domain, for example defense and security, space, engineering, medicine and transportation. Particular success stories include the Real-time Platform Reference FOM (RPR FOM), NATO Education and Training Network (NETN) FOM and the upcoming Space Reference FOM.

As experience from developing FOMs have been gathered, HLA has been extended and matured over time. HLA IEEE 1516- 2000 introduced well-defined data types and the use of XML syntax. HLA IEEE 1516-2010 introduced modular FOMs. Still, some challenges exist, in particular for making flexible extensions to reference FOMs. The HLA standard is now open for revision for a new version, nick-named HLA 4. This paper explains some of the proposed new features for object modeling. Several of them are based on requirements from the RPR FOM community but are useful for most FOMs.

One important requirement is to be able to make a more fine-grained extension of an already existing object model using additional FOM modules. There are four cases for this:It should be possible to add more attributes to an existing object class, using a new FOM module. The same applies to interaction classes where new parameters need to be added. A typical RPR FOM use case is to add more attributes to the standard Aircraft class.

It should be possible to specify more Dimensions for DDM filtering to an existing object class or interaction class to meet the requirements of a particular federation. A typical RPR FOM use case is to be able to add Lat/Long based filtering of platforms in a battlefield.

It should be possible to add more enumerators to an existing enumeration. A typical RPR FOM use case is to be able to add new entity types, that don’t exist in the standard SISO-REF-010 enumerations.

It should be possible to add more variants to an existing variant record data type. A typical RPR FOM use case is to be able to add alternative encodings that describe new data links to the Signal interaction. It has also been proposed to be able to clearly specify references, for example that the firing entity parameter of a fire interaction refers to a specific platform instance.

This paper explains these new features as well as how they can be used to simplify FOM development and enhance interoperability while maintaining backwards compatibility.

Authors: Björn Möller, Mikael Karlsson
Publication: Proceedings of 2019 Winter Simulation Innovation Workshop, 2019-SIW-023, Simulation Interoperability Standards Organization, February 2019

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Lessons Learnt from Distributing Video oven an HLA Backbone

Presentation only, Proceedings of 2018 Fall Simulation Interoperability Workshop, 18F-SIW-046, Simulation Interoperability Standards Organization, September 2018

Authors: Thomas Brännström, Stefan Sandberg
Publication: Simulation Interoperability Standards Organization, September 2018

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