Internet DRAFT - draft-lee-asdf-digital-twin
draft-lee-asdf-digital-twin
ASDF Working Group H. Lee
Internet-Draft ETRI
Intended status: Standards Track J-S. Youn
Expires: 5 September 2024 Dong-eui Univ
Y-G. Hong
Daejeon University
4 March 2024
Extended information of Semantic Definition Format (SDF) for Digital
Twin
draft-lee-asdf-digital-twin-01
Abstract
An SDF specification can describe the definition of a Things, i.e.,
physical objects and their associated interactions and express the
various information that be exchanged for the interactions.
Therefore, the SDF format can be used to define the behaviour of an
object and its associated data model and interaction model in a
digital twin system that has an object as a component. In a digital
twin system, interactions between physical and virtual objects, as
well as interactions of objects existing in the different digital
twin systems, are performed over a network, which is important to
provide location information of objects during interactions. This
document specifies the extension information of SDF to represent the
location information of an objects.
Status of This Memo
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This Internet-Draft will expire on 5 September 2024.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SDF Location Extension for Digital Twin . . . . . . . . . . . 4
3.1. Namespaces . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Qualities of sdfLocation . . . . . . . . . . . . . . . . 4
3.2.1. locationType . . . . . . . . . . . . . . . . . . . . 5
3.2.2. target . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.3. description . . . . . . . . . . . . . . . . . . . . . 6
3.2.4. label . . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Example location description with sdfType links . . . . . 6
3.4. Example location description with geographical
information . . . . . . . . . . . . . . . . . . . . . . . 7
3.5. Example location description with relative information . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Digital twin is a digital representation of an object of interest and
may require different capabilities (e.g., synchronization, real-time
support) according to the specific domain of application [Y.4600].
Digital twin systems help organizations improve important functional
objectives including real-time control, off-line analytics,
predictive maintenance by modelling and simulating of objects in the
real world. Therefore, it is important for a digital twin system to
represent as much real-world information about the object as possible
when digitally representing the object. A procedure for representing
an observable Thing, as known as a physical asset or an object of
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interest, as a digital twin in a domain is as follows:
* defining a purpose for expressing the observable object as a
digital twin in the domain
* organizing data based on the roles of the observable object in the
domain
* configuring the observable object into the digital twin based on
the data for the purposes
* interworking with a digital twin of each of other domains in which
the observable object performs a different role
* synchronizing the observable object and the digital twin
Nowadays, digital twin systems are applied in various domains
including medical, manufacturing, farm, transportation, etc. And a
common format is needed to represent the objects in the domains as
digital twins. An SDF specification [I-D.ietf-asdf-sdf] can be used
for the purpose of digital representation of objects in a digital
twin system. However, because the SDF specification only provides a
basic model for digital representation, it cannot represent objects
location information. The location information of the object is the
important information to digitally representation of the object.
This document extends the basic SDF specification by adding a new
keyword "location" to represent an object as a digital twin. This
new keyword is needed to adequately represent the current location of
the object, which is helpful for users to manage the domain
efficiently.
2. Terminology
This specification uses the terminology specified in
[I-D.ietf-asdf-sdf] in particular "Class Name Keyword", "Object", and
"Affordance".
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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3. SDF Location Extension for Digital Twin
This section defines a new SDF Class Name Keyword, sdfLocation, that
can be used to represent the location of a thing or an object as
digital twin. The location definitions are on class-level, and
describes the use of sdfLocation [I-D.ietf-laari-asdf-sdf-relations].
3.1. Namespaces
The SDF namespace block can be used to provide CURIE prefixes for
external ontologies for use with sdfLocation extension. For example,
in case of SAREF (Smart Applications REFerence ontology) ontology
extension for buildings [saref4bldg], we can use the following
namespace definition:.
{
"namespace": {
"saref": "https://saref.etsi.org/saref4bldg/v1.1.2/"
}
}
3.2. Qualities of sdfLocation
This section defines the qualities of the sdfLocation. These
qualities are used to define the potential type of the sdfLocation.
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+==============+========+==========+========================+
| Quality | Type | Required | Description |
+==============+========+==========+========================+
| locationType | string | yes | What kind of location |
| | | | these definitions have |
+--------------+--------+----------+------------------------+
| target | string | no | Target model for the |
| | | | location |
+--------------+--------+----------+------------------------+
| description | string | no | Description of the |
| | | | location |
+--------------+--------+----------+------------------------+
| label | string | no | Short text describing |
| | | | the location |
+--------------+--------+----------+------------------------+
| property | object | no | Additional properties |
| | | | for this location |
+--------------+--------+----------+------------------------+
| $comment | string | no | Additional comments |
| | | | for implementors |
+--------------+--------+----------+------------------------+
Table 1: Qualities of sdfLocation
3.2.1. locationType
The locationType quality describes the type of location including
geographical or relative information [ISO23247-3]. This can use
different descriptions, such as GPS, postal address, relative
location. The purpose of the locationType is to represent the
current location of an sdfThing or an sdfObject. For example, the
locationType can be defined as "218 Gajeong-ro, 7th building in ETRI,
WorkUnit #3 in ETRI branch #2" and so on.
3.2.2. target
The "target" field defines to which definition or ontology term this
definition with sdfLocation has a location to. For example, this can
be #/sdfObject/location, when the target location of an object is
defined in the same SDF model.
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"namespace": {
"exont": "https://example.com/relationOntology",
"saref": "https://saref.etsi.org/core/v3.1.1/"
},
sdfObject: {
"Humidity": {
"description": "Example Humidity object",
"sdfProperty": {
...
},
"sdfLocation": {
"postalAddr": {
"locationType": "exont:postal-addr",
"target": "saref:PostalAddress",
"description": "address of object",
"label":"postcode"
}
}
}
...
}
3.2.3. description
The "description" field defines the location. For SDF version 1.1,
the description is a string.
3.2.4. label
Short text describing the location, similar to label quality in other
SDF definitions.
3.3. Example location description with sdfType links
This extension allows you to describe location from the SDF model to
various (SDF or other) definitions. For link data types for
affordance, for example, for link properties that can be accessed and
modified during runtime, the "sdfType for links" extension
[I-D.bormann-asdf-sdftype-link] can be used instead. In the
following example, we have a definition for location with the postal
address format:
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sdfObject: {
"example-object": {
"description": "example object",
"sdfProperty": {
...
},
"sdfLocation": {
"postalAddr": {
"locationType": "exont:postal-addr",
"target": "saref:PostalAddress",
"description": "Postal address of a company", "218 Gajeong-ro ...",
"label":"34129",
"property":"company address"
}
}
}
...
3.4. Example location description with geographical information
This example allows you to describe location of sdfThing or sdfObject
with geographical information.
sdfObject: {
"sdfLocation": {
"sdfData": {
"geoLocation" : {
"latitude": "string",
"longitude": "string"
"altitude": "string"
}
...
"Boat_#1": {
"latitude": "35.5188233791372",
"longitude": "129.37308376484913",
"altitude": "0.0"
}
}
}
}
3.5. Example location description with relative information
This example allows you to describe location of sdfThing or sdfObject
with relative information including geographical information.
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sdfObject: {
"sdfLocation": {
"sdfData": {
"geoLocation" : {
"latitude": "string",
"longitude": "string"
"altitude": "string"
}
"relativeLocation" : {
"relative-x": "integer",
"relative-y": "integer"
"relative-z": "integer"
"unit":"cm"
}
...
"Boat_#1": {
"latitude": "35.5188233791372",
"longitude": "129.37308376484913",
"altitude": "0.0"
}
"Heater_A_in_the_Boat_#1": {
"latitude": "35.5188233791372",
"longitude": "129.37308376484913",
"altitude": "0.0"
"relative-x": "7215",
"relative-y": "1324"
"relative-z": "217"
}
}
}
}
4. Security Considerations
TODO Security
5. IANA Considerations
This document has no IANA actions.
6. References
6.1. Normative References
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[I-D.bormann-asdf-sdftype-link]
Bormann, C., "An sdfType for Links", Work in Progress,
Internet-Draft, I-D.bormann-asdf-sdftype-link, 3 December
2023, <https://datatracker.ietf.org/doc/html/I-D.bormann-
asdf-sdftype-link>.
[I-D.ietf-asdf-sdf]
Koster, M., Bormann, C., and A. Keränen, "Semantic
Definition Format (SDF) for Data and Interactions of
Things", Work in Progress, Internet-Draft, draft-ietf-
asdf-sdf-18, 29 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-asdf-
sdf-18>.
[I-D.ietf-laari-asdf-sdf-relations]
Laari, P., "Extended relation information for Semantic
Definition Format (SDF)", Work in Progress, Internet-
Draft, I-D.ietf-laari-asdf-sdf-relations, 13 September
2023, <https://datatracker.ietf.org/doc/html/I-D.ietf-
laari-asdf-sdf-relations>.
[ISO23247-3]
"Automation systems and integration Digital twin framework
for manufacturing - Part 3: Digital representation of
manufacturing elements, ISO 23247-3.", October 2021,
<https://www.iso.org/standard/78744.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[Y.4600] Union, I. T., ""Recommendation ITU-T Y.4600 (2022),
Requirements and capabilities of a digital twin system for
smart cities.", August 2022.
6.2. Informative References
[saref4bldg]
Poveda-Villaln, M. and R. Garcia-Castro, "SAREF extension
for building", 5 June 2020,
<https://saref.etsi.org/saref4bldg>.
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Authors' Addresses
Hyunjeong Lee
Electronics and Telecommunications Research Institute
218 Gajeong-ro, Yuseong-gu
Daejeon
34129
South Korea
Phone: +82 42 860 1213
Email: hjlee294@etri.re.kr
Joo-Sang Youn
DONG-EUI University
176 Eomgwangno Busan_jin_gu
Busan
47340
South Korea
Phone: +82 51 890 1993
Email: joosang.youn@gmail.com
Yong-Geun Hong
Daejeon University
62 Daehak-ro, Dong-gu
Daejeon
34520
South Korea
Phone: +82 42 280 4841
Email: yonggeun.hong@gmail.com
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