Research On The Feature Interaction In Semantic Featrure Modeling

Feature modeling is product-oriented and it is an important milestone of CAD development,which really makes integrated CAD/CAPP/CAM possible.It is also the theory and technological foundation of solving products problems.Semantic feature modelling is a declarative feature modelling approach that not only provides a well-defined specification of feature semantics,but also effectively maintains this semantics during the modeling process.In fact ,one of the basic ideas of feature –based modeling is the ability to associate functional information to shape information in a feature model,that form the semantic of the feature together.Bidarra,R.reserches feature semantics,e.g. the detailed description of feature class ,and describes that validity maintenance of semantic feature models is its final aim.Feature class specification is classified into three categories : (1)specification of feature parameterised shape that encapsulates elements,parameters and natures of feature shape;(2)specification of feature validity conditions that involves a varity of constraints such as algebraic constraint,dimension constraint,semantic constraint and interaction constraint;(3)interface of user-supplied data to the feature model that determines the appropriate normal positions and orientations such as attach constraint and geometric constraint.Embedding validity criteria in each feature class makes feature adjustable,provide the mechanism of shape inheritance and shape composition in order to achieve the user-definde and compound feature.So it enhances the efficiency of designing process and improves the ability of modeling.Feature model validity maintenance is the process of monitoring each modeling operation in order to ensure that all features in feature model conform to the semantics specified in their respective classes.The basic principles of validity maintenance can be summarized as follows:(1)A modeling operation,to be considered as valid,should yield a feature model that conforms to all constraints.This ensures that every feature in the model conforms to the designer intent explicitly specified up to that moment.(2)After an invalid modeling operation,the user should be assisted in overcoming the constraint violations in order to recover model validity again.Maintaining feature model validity,e.g.feature semantic validity is by means of validity constraints that is the member in the defination of feature.At the creation of a feature and later modeling step,validity checking ,whether those constraints are valid,indicates feature validity.Many validation violations,e.g.constraint violations are caused by feature interaction.So feature interactions play a major role in semantic feature modeling system,either the specification of featur class or validity maintenance of feature model.Feature-based modeling systems fail to adequately maintain feature semantics, mainly due to an incomplete classe of feature interaction phenomena. Aiming at researching feature interaction mechanism and according to a definition and influence of feature interactions, this paper that based on the technology of oriented-object, presents a new taxonomy for feature interaction, and determines the feature interaction scope of each operation.It describes the role and the excuting process of interaction manager in feature model validity maintenance,proposes a solving method of semantic feature interaction mechenism in HUST-CAID system,and illustrated.This paper point out the next research key. Ultimately oriented-object technology introduced in this method ensures consistency and validity of feature semantics in semantic feature modeling systems.