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Application module:
Contextual shape positioning |
ISO/TS 10303-1027:2021(E)
© ISO
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This clause specifies the information requirements for the
Contextual shape positioning
application module. The information requirements are specified as the
Application Reference Model (ARM) of this application module.
NOTE 1 A graphical representation of the information
requirements is given in
Annex C.
NOTE 2 The mapping specification is specified in
5.1. It shows how
the information requirements are met by using common resources and
constructs defined or imported in the MIM schema of this application
module.
This clause defines the information requirements to which implementations shall
conform using the EXPRESS language as defined in ISO 10303-11.
The following begins the
Contextual_shape_positioning_arm
schema and identifies the necessary external references.
WARNING:
For users and implementers of this standard please note that the Geometric Modeling methodology employed herein is unique
and therefore limited solely to this usage, and only this usage, due to its
uncommon characteristics.
ISO 10303 defines a critical associativity between geometry and topology that is carefully defined and constrained to provide
the reproducibility, reliability, robustness, and completeness necessary in
industrial product modeling based on vetted mathematical foundations (i.e., see Section "Geometric model schema" of ISO
10303-42). ISO 10303 employs a methodology of building hybrid product
structure (non-geometric) and (geometric) assembly model structures that associate a rigid body tensor transform to place
geometric models of the parts in the geometric model of the assembly. Those
hybrid structures decompose the hybrid structure, the relationship to the transform, and the transform into separate EXPRESS
constructs, however they are designed and integrated to function as a
single model.
The reference in a hybrid assembly model (i.e., Geometric_model_relationship defined in AM 1403)
from a context_dependent_shape_representation
to a combined subtype of shape_representation_relationship
and representation_relationship_with_transformation to create associations between Geometric models deviates from the above approach in ISO 10303.
It should therefore be strictly limited to the use
of Wiring harness assembly design, not utilized outside of that scope, with care taken by users and implementers to understand
its particular construction, limitations, and conditions.
EXPRESS specification:
*)
SCHEMA Contextual_shape_positioning_arm;
(*
The following EXPRESS interface statements specify the elements
imported from the ARMs of other application modules.
EXPRESS specification:
*)
USE FROM
Geometric_model_relationship_arm;
--
ISO/TS 10303-1403
USE FROM
Shape_property_assignment_arm;
--
ISO/TS 10303-1032
(*
NOTE 1
The schemas referenced above are specified in the following
part of ISO 10303:
| Geometric_model_relationship_arm |
ISO/TS 10303-1403 |
| Shape_property_assignment_arm |
ISO/TS 10303-1032 |
NOTE 2
See Annex C,
Figures
C.1and C.2
for a graphical representation of this schema.
This subclause specifies the ARM types
for this application module. The ARM types and
definitions are specified below.
The product_context_select type allows for the designation of the data
types
View_definition_relationship and Product_occurrence_definition_relationship.
Items of the product_context_select select can be used as
product_context
for an
Contextual_shape_representation.
EXPRESS specification:
*)
TYPE
product_context_select =
SELECT
(View_definition_relationship,
Product_occurrence_definition_relationship);
END_TYPE;
(*
The template_instance type allows for the designation of the data
types
Geometric_placement_operation and Geometric_model_relationship_with_transformation.
EXPRESS specification:
*)
TYPE
template_instance =
SELECT
(Geometric_placement_operation,
Geometric_model_relationship_with_transformation);
END_TYPE;
(*
This subclause specifies the ARM entities for this
module. Each ARM application entity is an atomic element that
embodies a unique application concept and contains attributes
specifying the data elements of the entity. The ARM
entities and definitions are specified below.
An Axis_placement_mapping is a geometric transformation that is defined by a source and a target
Representation_item
that are mapped onto each other.
The default kind of source and target types defined in this module are
Axis_placements
only.
Other application modules may define further subtypes of
Representation_item
that can be used to define the mapping.
NOTE
By construction, the determinant of the transformation matrix equals one.
EXPRESS specification:
*)
ENTITY Axis_placement_mapping;
source : Axis_placement;
target : Axis_placement;
END_ENTITY;
(*
Attribute definitions:
source:
the
Axis_placement
that plays the role of source in the transformation.
target:
the
Axis_placement
that plays the role of target in the transformation.
A Contextual_shape_representation is an association of a
Geometric_model_relationship
to a product structure relationship.
The association between the
Geometric_model_relationship
and the product structure relationship
is established in such a way that the
related view
of the product structure
corresponds to the
rep_1
attribute of the
Geometric_model_relationship
and the
relating view
of the product structure corresponds to the
rep_2
attribute of the
Geometric_model_relationship.
The product structure relationship provided by a
product_context_select
is either a
View_definition_relationship
or a
Product_occurrence_definition_relationship.
The
Geometric_model_relationship
may be a
Geometric_model_relationship_with_transformation
that reflects the transformation between the
Geometric_models
of the corresponding product structure;
or the related and relating
Geometric_models
of the
Geometric_model_relationship
share the same
Geometric_coordinate_space.
NOTE
To provide consistency, the referenced
Geometric_models
are typically either directly or indirectly associated to the corresponding
primary_shape_representation
of the corresponding
Product_view_definitions.
EXPRESS specification:
*)
ENTITY Contextual_shape_representation;
product_context : product_context_select;
shape_representing_relationship : Geometric_model_relationship;
DERIVE
context_representation : geometric_representation_select := shape_representing_relationship.rep_2;
positioned_representation : geometric_representation_select := shape_representing_relationship.rep_1;
END_ENTITY;
(*
Attribute definitions:
product_context:
the role of the
product_context_select
for the Contextual_shape_representation.
shape_representing_relationship:
a role of the
Geometric_model_relationship
for the Contextual_shape_representation.
context_representation:
the
Geometric_model
in which the representation of the contextual shape is characterized.
positioned_representation:
the
Geometric_model
that contains the representation of the contextual shape in the context representation.
A Geometric_composition_with_operator_transformation is a type of
Definitional_representation_relationship
and a type of
Geometric_relationship_with_operator_transformation.
EXPRESS specification:
*)
ENTITY Geometric_composition_with_operator_transformation
SUBTYPE OF (Geometric_relationship_with_operator_transformation, Definitional_representation_relationship);
END_ENTITY;
(*
A Geometric_composition_with_placement_transformation is a type of
Definitional_representation_relationship
and a type of
Geometric_relationship_with_placement_transformation.
EXPRESS specification:
*)
ENTITY Geometric_composition_with_placement_transformation
SUBTYPE OF (Geometric_relationship_with_placement_transformation, Definitional_representation_relationship);
END_ENTITY;
(*
A Geometric_model_relationship_with_transformation is a type of
Geometric_model_relationship.
Each Geometric_model_relationship_with_transformation is either a
Geometric_relationship_with_placement_transformation
or a
Geometric_relationship_with_operator_transformation
EXPRESS specification:
*)
ENTITY Geometric_model_relationship_with_transformation
ABSTRACT SUPERTYPE
OF (ONEOF (Geometric_relationship_with_placement_transformation,
Geometric_relationship_with_operator_transformation))
SUBTYPE OF (Geometric_model_relationship);
WHERE
WR1: SELF\Representation_relationship.rep_1.context_of_items :<>: SELF\Representation_relationship.rep_2.context_of_items;
END_ENTITY;
(*
Formal propositions:
WR1:
Both geometric representations shall belong to different geometric contexts.
A Geometric_placement_model is a type of
Geometric_model
that contains exactly one
Geometric_placement_operation.
NOTE
A Geometric_placement_model can be used by the inherited attribute
primary_shape_representation
of a
Product_occurrence
to select a particular
Geometric_placement_operation
within the
Geometric_model
of an
Assembly_definition.
This usage is no longer recommended.
EXPRESS specification:
*)
ENTITY Geometric_placement_model
SUBTYPE OF (Geometric_model);
SELF\Representation.items : SET[1:1] OF Geometric_placement_operation;
END_ENTITY;
(*
Attribute definitions:
items:
a set of
Geometric_placement_operations
that the Geometric_placement_model is a collection of.
There shall exist exactly one
Geometric_placement_operation
for the Geometric_placement_model.
A Geometric_relationship_with_operator_transformation is a type of
Geometric_model_relationship_with_transformation
where the transformation is explicitly defined by a
cartesian_transformation
either in 2D or in 3D.
A Geometric_relationship_with_operator_transformation shall not be used for an assembly structure as it might result in shearing, scaling and mirroring of the
Geometric_model of the components of the assembly.
EXPRESS specification:
*)
ENTITY Geometric_relationship_with_operator_transformation
SUBTYPE OF (Geometric_model_relationship_with_transformation);
transformation : cartesian_transformation;
WHERE
WR1: SELF\Representation_relationship.rep_1.context_of_items\Geometric_coordinate_space.dimension_count :=: SELF\Representation_relationship.rep_2.context_of_items\Geometric_coordinate_space.dimension_count;
END_ENTITY;
(*
Attribute definitions:
transformation:
the
cartesian_transformation
that identifies the transformation for the Geometric_relationship_with_operator_transformation.
Formal propositions:
WR1:
The inherited attributes rep_1 and
rep_2
shall have representation values with the same dimensionality.
A Geometric_relationship_with_placement_transformation is a type of
Geometric_model_relationship_with_transformation
where the transformation is defined indirectly by one or several pairs of
Representation_items
that are mapped onto each other.
NOTE 1
In many cases a single pair of
Axis_placements
is used to define the transformation between the corresponding
Geometric_coordinate_spaces
of the affected
Geometric_models
so that the
Axis_placements
fall together.
NOTE 2
A Geometric_relationship_with_placement_transformation is the preferred mechanism to represent the transformation in an assembly structure as it guarantees
that the resulting transformation matrix is not shearing, not scaling and not mirroring.
EXPRESS specification:
*)
ENTITY Geometric_relationship_with_placement_transformation
SUBTYPE OF (Geometric_model_relationship_with_transformation);
transformation : Axis_placement_mapping;
WHERE
WR1: SELF\Representation_relationship.rep_1.context_of_items\Geometric_coordinate_space.dimension_count :=: SELF\Representation_relationship.rep_2.context_of_items\Geometric_coordinate_space.dimension_count;
END_ENTITY;
(*
Attribute definitions:
transformation:
a single, set or list of
Axis_placement_mappings
that define the transformation.
Formal propositions:
WR1:
The inherited attributes rep_1 and
rep_2
shall have representation values with the same dimensionality.
*)
END_SCHEMA; -- Contextual_shape_positioning_arm
(*
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