A Comparison of Manual vs. Online Grading for Solid Models

A Comparison of Manual vs. Online Grading for Solid ModelsRigorous assessment of students' solid modeling skills can be a time-consuming task for CADinstructors. Students may submit print outs of parts (screen shots) to demonstrate that the partswere completed, and these screen shots may include a feature tree (model tree) that shows theorder of feature creation. However, many aspects of the modeling strategy cannot be examinedby inspection of the feature tree alone. Parameters such as sketch dimensions and constraints,feature creation parameters, parent-child relations, and other factors that capture design intent arenot easily checked except by examination of the part file. Manual checking of part files is a time-consuming task, and impractical for large classes. Thus, students tend to make parts that "lookgood", but fail to incorporate robust modeling strategies. Without feedback to remedy theirmodels, students develop and perpetuate poor modeling practices.Limited attempts have been made to automate grading of solid models. Baxter1 used VisualBasic in conjunction with CAD software programming capabilities to query the database ofstudent part files. Dassault Systems2 uses the calculated mass properties values of SolidWorksmodels to check the geometric accuracy of parts modeled for their certification exams. Theseattempts are either limited in the ability to assess the model and/or require extensive knowledgeof the software and programming skills to develop assessment tools for specific parts. The toolsare not generic and cannot be applied to models of different parts.In this paper, we introduce the use of Pro/FICENCY, a PTC technology designed to automate theassessment of student parts and drawings, and ProToolkit, a programming utility within the solidmodeling system, in an effort to identify variations and mistakes, and thereby automaticallyassess students' modeling strategies. A comparison between automated and manual grading ofselected part files will be presented. We will also discuss the effort required to implement theprocedure for different parts.1 Baxter, D. and M. Guerci (2003), Automating an Introductory Computer Aided Design Courseto Improve Student Evaluation, ASEE Annual Conference, 2003.2 Dassault Systems (2012) MCAD Certification Programs,http://www.solidworks.com/sw/support/mcad-certification-programs.htm