An Intelligent System to Analyze Sketched Solutions to Open-Ended Truss Problems

Engineering students need practical, open-ended problems to help them build their problem-solving skills and design abilities. However, large class sizes create a grading challenge for instructors as there is simply not enough time nor support to provide adequate feedback on many design problems. In this work, we describe an intelligent user interface to provide automated real-time feedback on hand-drawn free body diagrams that is capable of analyzing the internal forces of a sketched truss to evaluate open-ended design problems. The system is driven by sketch recognition algorithms developed for recognizing trusses and a robust linear algebra approach for analyzing trusses. Students in an introductory statics course were assigned a truss design problem as a homework assignment using either paper or our software. We used conventional content analysis on four focus groups totaling 16 students to identify key aspects of their experiences with the design problem and our software. We found that the software correctly analyzed all student submissions, students enjoyed the problem compared to typical homework assignments, and students found the problem to be good practice. Additionally, students using our software reported less difficulty understanding the problem, and the majority of all students said they would prefer the software approach over pencil and paper. We also evaluated the recognition performance on a set of 3000 sketches resulting in an f-score of 0.997. We manually reviewed the submitted student work which showed the handful of student complaints about recognition were largely due to user error.