Feedback method from inspection to process plan based on feature mapping for aircraft structural parts

Abstract

The feedback from results of computer aided inspection is used by process planners (though a manual process) to improve machining processes to achieve desired quality. Mapping from inspection features to machining features is a practical method to automate this process. In NC machining of aircraft structural parts, composite machining features, surface joining and complex topological adjacency between free-from surfaces make this kind of mapping (one-to-many mapping mostly) much more complicated. In this research, a new feature mapping based feedback method from inspection to process plan is proposed. The geometry of inspection features are categorized into three kinds of basic inspection elements: Axis, Plane, and Surface. Then, the one-to-many mapping is simplified into one-to-one mapping. The correspondence relationships between basic inspection elements and machining features are abstract as mapping rules to obtain the associations between the basic inspection elements and candidate machining features. Through geometric reasoning, the basic inspection elements are mapped into machining features. Then, the measure data as feedback can be transferred to process planner for improving machining process. The optimized machining process will be stored in knowledge base for reusing. A case study is presented in this paper to demonstrate the proposed method. A prototype feature-based on-line inspection system has been developed and applied for machining aircraft structural parts in a large aircraft manufacturer.