The focus of this research is to develop a prototype
expert system for softwood lumber grading. The grading
rules used in the knowledge base of the system are based on
Western Lumber Grading Rules 88 published by the Western
Wood Products Association. The system includes 27 grades
in Dimension, Select/Finish, and Boards categories.
The system is designed to be interactive and menu-driven.
The user input to the system consists of lumber
size, grade category, and type, location and size of
defects for each face. The system then infers the grade
corresponding to each face, and an overall grade for the
lumber. The system provides limited explanation
capabilities.
Evaluation of the system was performed using 85
samples of pre-graded Siberian larch 2x4x12s in Structural
Light Framing category. The initial evaluation was
performed using the two wide faces of boards. Results
indicated a 60 percent match between the grade assigned by
the human expert and the system. The largest cause of
deviation was exclusion of defects on the two narrow faces.
The knowledge base was expanded to include the two narrow
faces; the match rate improved to 76.5 percent.
Evaluations for other grading categories need to be
conducted in the future to assess the adequacy of the
knowledge base.
The prototype development concentrates on selected
defect characteristics for each grade. These
characteristics are clearly defined and described in the
rule book, and are usually the most frequently encountered
defects on softwood lumber. The knowledge base needs to be
refined and expanded if additional factors such as knot
positions relative to each other, warp, manufacturing
imperfections and clustering of defects are to be
considered. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30041 |
| Date | 05 May 1993 |
| Creators | Zeng, Yimin |
| Contributors | Randhawa, Sabah |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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