Abstract: On the foundation of automatic identifying the feature, a kind of hierarchical tolerance representation model based on feature is proposed by using polychromatic sets the rock-bottom frame of this hierarchical tolerance representation model is described by using polychromatic sets. Then, using the reasoning matrix between the unified colors and individual colors of polychromatic sets the reasoning of the constraint primitive (CP) tier is achieved, and the method and process of the reasoning are proposed. Finally, take the feature of hole as example, the methods and process of the reasoning discussed are validated.

Key words: Constraint primitive tier, Polychromatic sets, Rock-bottom frame, Tolerance information