# OntoIMM: An Ontology for Product Intelligent Master Model
## 3 Extensions to Core Product Model for Intelligent Master Model
### Product Control Structure Model  
Product control structure model (PCS) allows engineers to layout the product configuration and controls engineering changes in a top-down format. What-if analysis at different levels is facilitated by allowing the designers to evaluate alternate configurations or to make parametric changes [7; 8]. PCS is  
Figure 2: The main concepts of design process mode. intelligently modified by KBE (especially knowledge rules) to drive the change of product structure and configurations, and thereby intelligently scales a complete product or components of the product. The hierarchical decomposition of product into its systems, subsystems, and components of PCS are represented by multilayer skeleton which is the determined factor of product configuration. It controls the model shape, feature dimensions and part locations, and assembly relationships through high-level product attributes and key datum planes, axes, points and parameters. Once subsystems establish and reference the top-level datums, each subsystem can be designed independently in a distributed format and later be assembled automatically. Within PCS, the morphological features of components may be represented by preliminary, simplified geometry or just datums, the topological relationships between components may be controlled by geometry interfaces. Geometry interface is a kind of interface to represent the spatial location, orientation and assembly relationship of parts and components. Interface templates may be defined to represent the geometry interface information (including category, geometry description, interface parameters, and constraints) and reused, since the interfaces tend to be stable for the similar engineering product. The main concepts of PCS are shown in Figure 3.  
The following concepts are needed for modeling the PCS model. ProductControlStructure is designated for controlling product structure in morphological or topological ways based on knowledge rules. Besides the basis attributes of name, type and information inherited from the class Artifact, it also includes multilayer skeleton, control parameter, and driven knowledge. MultilayerSkeleton is the determined factor of product configuration, which controls the model shape, feature dimensions and part locations, and assembly relationships, through high-level product attributes and key datum planes, axes, points, and parameters. ControlParameter is a parameter set of configuration parameters and sizes which drive the generation or update of product model. Within multilayer skeleton, the top skeleton is a bridge connecting to each other and storing the position relation and global parameters of each part. These global parameters control the configuration and size of the subordinate parts. The lower skeleton replicates these parameters and coordinates the skeleton information of its own to determine the overall configuration size of the current component, and controls the position relation of the subordinate parts, and passes down the global parameters. InterfaceTemplate represents the interface relationships between levels and inner level of product assembly can be instantiated as an interface of multilayer skeleton. A PCS may include several interfaces as it is an assembly structure. For example, gun PCS may have interior ballistic interface, gun-bullet interface, muzzle interface, barrel interface. These properties of InterfaceNO, InterfaceFunctionStructure, InterfaceGeometry, InterfaceLevel, Interfacekinetic, InterfaceParameter, and InterfaceAssociation may be used to define an InterfaceTemplate. Figure 3: The main concepts and relationships of product control structure (PCS). DrivenKnowledge, especially design rules and experience knowledge, are used to intelligently modify the PCS in morphological or topological ways. It drives changes to parameters that define cross-sections and features and thereby intelligently scale a complete product or components of the product. Driven knowledge is a specialization of design knowledge.