05: Twin instances

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TRAIL: A SysML Pattern for Digital Twinning
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INTERMEDIATE
UML keywords
Object Diagram
object
instance
InstanceSpecification
SysML keywords
object diagram
Keywords
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SysML Block Definition Diagram (BDD)
UML Object diagram
Before we explore applications of the pattern, it's instructive to see the Blocks also instantiated as simple "objects":
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See those variants again?
Webel Twin Pattern: A DigitalTwin may use one or more variantEntity:@Entity[0..*] to explore the impact of changes (optimisation studies, trade off studies) and then use them to drive the PhysicalEntity into a desired state (via its ControlSystem).
We'll see when we apply the pattern that they can carry values OTHER than the current best digital encapsulation of the PhysicalEntity.
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06: Focus BDD for EntityRepresentation
Notes
[CONVENTION]{SUBJECT-TO-CHANGE} Webel: Convention: [MIGHT CHANGE]: An '@' prefix in a DigitalTwin model indicates a «digital» Block that maps a non-digital «mappable» Block.
[POLICY]{STRICT} Webel Twin Pattern: A DigitalTwin must model processes and the entities they act on separately.
[POLICY]{STRICT} Webel Twin Pattern: A «digital» DigitalEntity (a.k.a. @Entity) encapsulates strictly geometrical, spatial, and material aspects of a «physical» PhysicalEntity only. BY DEFINITION of this pattern it DOES NOT encapsulate processes!
[POLICY]{STRICT} Webel Twin Pattern: It is a DigitalEntity (a.k.a. @Entity) - not the DigitalTwin that owns it - that directly «replicates» geometrical, spatial, and material aspects (only) of a single PhysicalEntity.
[POLICY]{STRICT} Webel Twin Pattern: A PotentialPhysicalAsset is «digital», not «physical». It is used to acquire (an existing) or create (build, manifest, make) an «physical» ActualPhysicalAsset, which is a special case of «physical» PhysicalEntity.
[POLICY]{STRICT} Webel Twin Pattern: A DigitalTwin manages a control loop including a PhysicalEntity and a DigitalEntity (a.k.a. @Entity) that «replicates» it. It typically includes at least one Sensor and at least one Actuator.
[WARNING]{INFORMATIVE} WARNING: In natural language casual conversation one often hears people speaking of a digital twin "replicating" or "twinning" a physical entity. If you do it that way literally, you will NOT have anything to manage the control system loop!
[POLICY]{STRICT} Webel Twin Pattern: A «digital» DigitalEntity (a.k.a. @Entity) is NOT a representation! It is a digital encapsulation (it can only be perceived at the level of "bits and bytes"). It HAS many representations (such as views)!
[POLICY]{STRICT} Webel Twin Pattern: The primary aim of the digitalEntity:@Entity of a DigitalTwin is to replicate its physical:PhysicalEntity as closely as possible (not to explore variants).
[POLICY]{STRICT} Webel Twin Pattern: A DigitalTwin may use one or more variantEntity:@Entity[0..*] to explore the impact of changes (optimisation studies, trade off studies) and then use them to drive the PhysicalEntity into a desired state (via its ControlSystem).
Snippets (quotes/extracts)
 Digital twins are dynamic, data driven, multi-dimensional digital replicas of a physical entity.
 They encompass potential or actual physical assets, processes, people, places, systems, devices and the natural environment.
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