Research On Electrical Circuit Drawing Recognition And Intelligent Design

Electrical circuit drawing is one of the most important engineering drawings in relay circuit system design. And it is also the foundation of other design works. Using intelligent electrical CAD software is helpful for designers to save time and improve efficiency. In addition, in order to make full use of existed drawing resources, electrical circuit drawing plotted by general CAD software should be automated recognized and conversed to standard format of electrical CAD software. Therefore, doing research about the method of electrical circuit drawing recognition and intelligent design and developing a corresponding CAD system is a significant and valuable work.This paper, based on the summarization of the state of arts of symbol recognition and electrical CAD, studies the representation and recognition of electrical symbols and the intelligent design of electrical circuit drawing, and develops an electrical CAD system. The achievement is as the following:1. Propose a novel method of electrical circuit drawing recognition. First, separate and extract electrical symbols from drawing according to their graphic characters. Represent electrical symbols by the attributed graph with two level attributes. Extract primary graphic elements as nodes and geometry site relationship between them as edges. Put forward four attributes, which are invariant to changes of translation, rotation, scale and mirror transformation. Then filter database of model graphs to reduce matching times and use Ullman's algorithm to recognize symbols. Finally, extract labels and connection relation between electrical elements.2. Propose methods of intelligent design of electrical circuit drawing. Make use of the character that CAD drawings are separated into blocks and layers to design the standard circuit module using parameters. Use electrical element database to store electrical information in circuit drawings and index to represent complicated electrical element. It unifies label and store position of the text in order to make it consistent in reading and writing and easy to check the error. It also summarizes the nonstandard situations in the process of drawing and designs a drawing repair method to search and repair these errors. Finally it adopts attributed relational graph to represent wire lines in drawing and extract connection relation between electrical elements.3. Based on the above approaches, the author uses ObjectARX to design and develop an electrical circuit drawing recognition and intelligent design system running under AutoCAD platform. Designers can complete most of the electrical circuit design work using this...