Visualization, Freehand Drawing, Solid Modeling, and Design in Introductory Engineering Graphics

Transcription

1 Visualization, Freehand Drawing, Solid Modeling, and Design in Introductory Engineering Graphics Session 12d2 Jeffrey L. Newcomer, Robert A. Raudebaugh, Eric K. McKell, and David S. Kelley Engineering Technology, Western Washington University, Bellingham, WA, Abstract: The Engineering Technology Department at Western Washington University supports programs in Manufacturing, Plastics, and Electronics Engineering Technologies, as well as Industrial Technology, Industrial Design, and Technology Education. For all of our students, the first course in our department is Engineering Graphics I. In order to serve such a broad spectrum of students, we need to have a broad-based introductory graphics class. Furthermore, it no longer makes sense, given the variety of powerful 3-D solid modeling packages available today, to teach students 2-D drafting techniques, either with a T-square or on a computer. Thus we have adopted a new, department wide structure for our introductory graphics class that uses artbased freehand drawing techniques along with a nonparametric 3-D solid modeling package to help our students develop basic visualization skills that are transferable to the computer tools they will use in their various disciplines. Because, we also want our students to be designers and problem solvers rather than technical drafters, we are concentrating on developing general skills rather than having them become proficient in a specific software package. Thus for the first seven weeks of the quarter we alternate between using traditional art techniques to teach freehand drawing, and using Rhinoceros to teach basic solid modeling and computer drawing techniques. In the latter part of the class we introduce students to basic rules of technical drawing so that they can properly document their work. In addition, we cover the design process and use individual design projects so that students learn to view drawing and computer modeling as tools in the design process instead of ends in and of themselves. This format is a departure from traditional approaches to teaching a first course in Engineering Graphics, and the results of it have been very positive. Students show improved visualization and sketching skills, and an appreciation for the role of drawing in the design process. Introduction The Engineering Technology Department at Western Washington University supports programs in Manufacturing, Plastics, and Electronics Engineering Technologies, as well as Industrial Design, Industrial Technology, and Technology Education. As the first course that most students take in our department, Engineering Graphics I presents a challenge for our faculty. Certainly we need to cover basic concepts in graphics and design while helping students to develop or refine their visualization skills. In addition, we need to provide them with a course that will give them an opportunity to do creative and interesting work in order to get them excited about graphics and design, regardless of their intended major. Traditional approaches to engineering graphics using 2- D drafting and orthographic projections of mutilated blocks are certainly not going to accomplish our goals of providing creative and interesting work, and are unlikely to help students develop visualization skills if they do not already possess them [1]. The issue of developing student visualization skills remains far more serious than making engineering graphics a creative and interesting experience. While we have not developed a research program that allows us to make claims as to the exact nature of visualization or the best ways to develop it [2], we do understand that historically visualization is a necessary skill for innovative engineering designers [3]. The ability to think visually and to communicate visual ideas with others is essential to the design process. Moreover, we want to teach our students to be designers who approach open-ended problems with an organized solution method and a good set of supporting tools, not train them to be technical drafters whose main responsibility is to document the designs of others. Course Goals and Objectives Our basic goal for Engineering Graphics I is to introduce students to the fundamentals of engineering graphics and design while fostering their creativity, and providing them with tools and techniques by improving their visualization and drawing skills. The obvious approach given the current collection of drawing software is to use a 3-D solid modeling package to teach the fundamentals of computer drafting. There has been some research done on solid modeling and visualization [4-6], and not surprisingly, given that we live in a three-dimensional world, solid modeling has been shown to improve student visualization skills more effectively than traditional 2-D drafting techniques. We had to ask ourselves, however, if we could really expect students to develop visualization skills and get excited about design while trying to wrestle with a professional parametric modeling package. Moreover, we want to avoid letting the course become a training course for using a specific software package, which is always a danger if the software is complex and difficult to use. In the end, we selected a non-parametric modeling package called Rhinoceros. The advantage of this program is that it allows for free form design with great 12d2-1

2 ease, so students are able to model their designs on the computer with minimal frustration. The second component of our strategy for developing student visualization skills is to employ freehand drawing techniques from the world of art. Raudebaugh developed a text [7], based largely on the approach described by Betty Edwards [8], that takes students through the same type of exercises that are frequently used in beginning art-based drawing classes, including blind and modified contour drawings and negative space studies. Using such drawing techniques to teach engineering graphics may sound like a strange approach, but it really gets students to focus on seeing and visualization. Metaphorically speaking, we decided to teach students the creative writing aspects of engineering graphics, putting off some of the grammar aspects until a future course. Using art-based freehand drawing is also not unheard of in engineering graphics [9,10]. Furthermore, the results of using an art-based approach have been positive, so it is somewhat surprising that such an approach is not used more commonly. Along with improving student visualization skills, artbased drawing techniques improve student sketching skills. Freehand sketching seems to be rarely taught in engineering graphics today, but it is still an extremely useful, some might say necessary skill for engineering design. Our approach, which is based upon one developed by Barr and Juricic [11,12], is that engineering graphics contributes to the design process in three levels: ideation drawings, communication drawings, and documentation drawings. Ideation drawings are generally sketches done early in the design process to begin the development of design ideas. Communication drawings are used to share ideas with everyone from design team members to customers, and range from those used to continue design development to those that are used in formal design presentations and advertisements. Documentation drawings are traditional engineering drawings that contain the information that is required to build parts in the design and complete the assembly. Documentation drawings are now almost exclusively done on computers, but ideation drawings and many communication drawings are still drawn by hand, sometimes on the nearest blank sheet or flat surface. Since the ability to draw is not a common skill, and many people are convinced that they are incapable of learning to draw, we use art techniques to teach students how to draw random objects around them such as hands, flowers, and pinecones before trying to teach them how to draw without a model to work from. The basic tenet of the approach used by Edwards [8] and Raudebaugh [7] is that students of drawing need to learn to see what is actually before them rather than trying to reproduce their conception of what they know in their mind the object should look like. For example, if you are trying to draw a long table, the analytical portion of your mind knows that the legs are all the same length. If you draw the legs equal length, however, the drawing will not look like the actual object because the perspective of depth will not exist. Thus the main goal of early drawing exercises is to get students to forget about what they are drawing and to just look at small portions of the object while concentrating on what they actually see. The effect of this approach is that students learn to gauge perspective much more accurately, and their drawings look much more realistic. This in turn gives them the confidence to begin sketching their own design ideas so that the drawings accurately represent their ideas and can easily be used to communicate these ideas to others. Given all that we try to accomplish in a ten week introductory engineering graphics class, it is important to acknowledge what we do not intend to accomplish. Due to our emphasis on visualization, sketching, and the creative aspects of design, we have room left to give only a synopsis of design documentation. So while we do cover the fundamentals of orthogonal views, including section and special views, and the basic rules of dimensioning, we certainly do not expect our students to be fully trained in these areas. Moreover, we do not leave ourselves the room to include CAD/CAM topics such as concurrent engineering and the use of rapid prototyping as some other programs have recently done [13]. We believe that we were justified in these decisions, as these topics are covered extensively in our Engineering Graphics II class, which is taken by almost all of the students who take the introductory course. In our department, only students who select Electronics Engineering Technology (EET) as a major do not take the second course in graphics. In addition, roughly 10% of the students who take Engineering Graphics I are either already in other departments, or elect to major in other departments, and do not take the follow-up course. We believe that neither students in the EET program, nor students from other departments need the in-depth training in design documentation, so we remain confident that we are providing our students with an appropriate amount of exposure to the knowledge and skills that they will be expected to possess in the future. Course Outline Engineering Graphics I is a 4 credit hour class that meets twice per week for three hours at a time over a ten week quarter. The basic course outline includes one day of computer graphics and one day of hand drawing each week. The course is considered to be a skills acquisition class, so lecture time is minimized to provide students with the maximum amount of time to work on exercises and projects while faculty are present to offer advice and feedback. In the Fall 1998 quarter, from which student data for this paper were generated, four different faculty members taught five sections of introductory graphics. As such, there was some variation between sections in terms of the exact amount of time spent upon each topic, the exercises used in class, and the design project assignments. The greatest variations be- 12d2-2

3 tween sections occurred in the design project assignments. All instructors did, however, begin with the same basic syllabus and cover the same topics in nearly the same order, with design coverage being the most significant exception. The course outline was created with the intention of covering similar subjects in computer modeling and freehand drawing in parallel to emphasize to students that these are merely different tools used in a design process. In actuality, students need about four weeks of basic instruction in the Rhinoceros modeling program, especially since most students had no computer drafting or modeling experience coming into the course, and a few had no computer experience at all. Most students also need about the same amount of instruction in basic drawing techniques to have the skill and confidence to draw their own ideas. In freehand drawing, early topics include blind and modified contour drawings, negative space studies, and techniques for drawing with proper perspective. In computer modeling, early topics include drawing 2-D shapes and creating solids and surfaces from 2-D shapes. Thus, the first four weeks are used to allow students to develop the knowledge base to use sketching and computer modeling as tools in a design process. During the early part of the Fall 1998 quarter, students in most sections were also introduced to the design process (one instructor elected to cover the design process near the end of the quarter instead). The following five-step design process was used: 1. State the Problem 2. Develop Design Specifications 3. Develop Design Concepts 4. Select a Design Concept (based upon 2.) 5. Develop and Document the Design Details While this is a simplified approach to design, it nevertheless presents the most important steps of a conceptual design process, and gives students a methodology to use while completing their design projects. Having a structured approach to design is important at this level, as students will commonly choose to develop their first idea instead of considering alternatives. Moreover, since an approach to design is a learned behavior [14], it is important to develop good design habits in students as early as possible. In sections where design was covered early in the class, students were given a design problem to work on during either the third or fourth week of the class. This allows time for students to define their problem statement and design specifications while basic material on sketching and computer drawing is being covered. In the fifth week of the quarter freehand sketching and computer drawing topics become truly parallel, with iteration drawing techniques, axonometric drawings, and shading in sketching, and drawing using solids on the computer. This is also when students are starting to develop concepts for their design projects, so they begin to get a chance to use their sketching techniques for drawing their ideas instead of random objects. In the second half of the course we drift into more traditional engineering graphics topics, covering orthogonal views, section and auxiliary views, the basics of dimensioning, and assembly drawings. Topics are covered in time to allow students to practice them and get some feedback before they have to apply them to their design projects. Students continue to do parallel assignments with freehand and computer drawing. We also introduce another computer program, since Rhinoceros does not have the ability to dimension. We use IntelliCAD for this purpose, and after a rough first week, most students discover that they have the skills and knowledge to do basic drawing in that package as well. Finally, all sections of the course use a final project in lieu of a final exam. Student Designs In the Fall 1998 quarter, two instructors used the same design projects: design of a solution to a storage problem of some kind, and design of a flashlight. On both projects students were required to follow the design process. For the initial project they worked over a period of eight weeks, turning in work for the various steps separately. By the time of the final project, most students were comfortable enough with the design process to independently work through the various steps in just over three weeks. An advantage of these two projects was that students were able to personalize them to their interests. Students problems ranged from storing shoes to snowboards. Even the flashlight solutions varied depending upon whether students wanted them for working on their cars, camping, biking, or just general use. Figures 1-4 show examples of two flashlights that were designed by students for final projects. Figures 1 and 3 show the computer generated communication drawings, and Figures 2 and 4 show the exploded assembly drawings of the same two flashlights. Both of these flashlights were designed to work with automobiles. The first flashlight (Figs. 1 and 2) was designed to be kept in a car for emergency situations, and has a magnet opposite the switch to allow the user to mount the flashlight on the car somewhere and still have two free hands. The second flashlight (Figs. 3 and 4) was designed to ease car maintenance. This flashlight also has a magnetic base to hold it in place, and the neck can be repositioned to focus light where it is needed. All of the drawings shown were completed with Rhinoceros. In addition, students also turned in initial hand sketches of their various design ideas, and dimensioned drawings of their projects done with IntelliCAD. 12d2-3

4 Figure 1: Student Designed Flashlight 1 F igure 3: Student Designed Flashlight 2 Student Feedback Figure 2: Exploded View of Student Designed Flashlight 1 Results One of the most striking things about this class was how much students seem to enjoy it. Due to the nature of the class being a first introduction to the field, backgrounds and experience of students vary significantly. Some students come in with a technical drafting background, and since we have an Industrial Design major, quite a few enter with very good hand drawing skills. As a result, not every student enjoys every portion of the class, and not every student excels. Nevertheless, students enjoy being able to draw and design on the computer enough that most students in the class stay and work on their own projects after they have finished their assignments. Most students also show an improvement in their drawing skills, and their confidence in their drawing skills increases as well. We designed a short questionnaire and received feedback from 79 students regarding how the course met their expectations, what they felt they gained from the course, and what role they saw visualization and sketching playing in the design process. Overall, we found that most students enjoyed the class and rated it highly, with many saying they would recommend the course to others. This also was evident on the university course review form, where the average course rating for all sections was roughly 4.3 out of 5. This was in spite of the fact that the course was not what students initially expected it was going to be. The majority of students found that they had learned more and had more fun than they expected, although four of students responding expressed some disappointment that they did not learn advanced CAD techniques in the class. The large visualization and freehand drawing aspect of the class also received general approval. Quite a few students expressed appreciation for the role of visualization and freehand drawing in the design process. One student commented: Without visualizing the product in 3-D you can t draw it and without drawing no one will understand your idea or concept. Another student wrote: I struggled with computer graphics in high school and junior high. Those hand drawings really helped me bridge art with graphics. I feel that I gained from every exercise. Another added: I now am able to take an idea in my head and easily express it to others. Amusingly, a few students also expressed surprise at their own ability to draw at the conclusion of the class. Nonetheless, there were a handful of students, 6 of respondents, who felt that there was too much freehand drawing in the class. Most of these students, however, were students who already were in or intended to major in Industrial Design, and they already had very strong visualiztion 12d2-4

5 and sketching skills. One student even suggested that the ability to sketch should be a prerequisite for entering the department. There were more students, however, who already possessed strong drawing skills who commented that they did not mind the practice, even if it was a bit boring for them some days. This was a novel approach to teaching students the fundamentals of engineering graphics and design, and the results were very pleasing. Students demonstrate improved visualization and freehand drawing skills, they quickly and enthusiastically learn basic computer solid modeling skills, and they produce excellent conceptual designs. Our future plans are to continue to use the same format to teach Engineering Graphics I, with only small changes to some in-class exercises in the immediate future. We are also considering testing the visualization skills of our students at the beginning and end of the course to provide some quantitative data to support our claims. Even so, we believe that this approach teaches our students necessary skills more effectively than traditional approaches to Engineering Graphics I. References [1] Bowers, D., Trends and Techniques in Imaging Science, Engineering Design Graphics Journal, Vol. 57, No. 3, 1993 pp Figure 4: Exploded View of Student Designed Flashlight 2 As with the visualization and drawing sections of the class, students had many comments on doing design projects, and all of them were positive. Students liked that they got to apply all of the skills that they learned in the class. Many also expressed an appreciation for the role of a design process. One student wrote: I came to realize the importance of the design process, starting with the problem statement, to make sure that your design meets all your needs as best it can. Another student commented: Before this class I thought design was just one idea that you work with until it [is] right. I ve learned that design is many ideas, and that a design needs to be compatible with many different factors. Students understanding of and appreciation for the design process was also evident in the work that they turned in for their projects, some of which was very impressive for an introductory course. Students were generally satisfied that they had learned valuable skills in the class. Moreover, the instructors were also pleased with the level of accomplishment that most of the students attained. The one common complaint that students had was with the level of difficulty of the course. Almost half of the students commented on the difficulty, but students were evenly divided between those who thought it was too hard and those who thought it was too easy. Conclusions [2] Miller, C. L. and G. R. Bertoline, Spatial Visualization Research and Theories: Their Importance in the Development of an Engineering and Technical Design Graphics Curriculum Model, Engineering Design Graphics Journal, Vol. 55. No. 3, 1991 pp [3] Ferguson, E. S., Engineering and the Mind s Eye, The MIT Press, Cambridge, 1993 [4] Devon, R., R. S. Engle, R. J. Foster, D. Sathianathan, and G.F. Turner, The Effect of Solid Modeling Software on 3-D Visualization Skills, Engineering Design Graphics Journal, Vol. 58, No. 2, 1994, pp [5] Leach, J. A. and R. A. Matthews, Utilization of Solid Modeling in Engineering Graphics Courses, Engineering Design Graphics Journal, Vol. 56, No. 2, 1992, pp [6] Miller, C. A., Enhancing Visual Literacy of Engineering Students Through the Use of Real and Computer Generated Models, Engineering Design Graphics Journal, Vol. 56, No. 1, 1992, pp [7] Raudebaugh, R. A., Visualization, Sketching and Freehand Drawing for Engineering Graphics, SDC Publications, in press [8] Edwards, B, Drawing on the Right Side of the Brain, J.P. Tarcher, Inc., Los Angeles, 1979 [9] Bowers, D., Cognitive Processing and the Teaching of Engineering Graphics, Engineering Design Graphics Journal, Vol. 50, No. 3, 1986, pp [10] Wiebe, E. N., Scientific Visualization: An Experimental Introductory Graphics Course for Science and Engineer- 12d2-5

6 ing Majors, Engineering Design Graphics Journal, Vol. 56. No. 1, 1992, pp [11] Barr, R. E., and D. Juricic, Development of a Modern Curriculum for Engineering Design Graphics, Engineering Education, Vol. 81, No. 1, 1991, pp [12] Barr, R. E., and D. Juricic, A New Look at the Engineering Design Graphics Process Based on Geometric Modeling, Engineering Design Graphics Journal, Vol. 56, No. 3, 1992, pp [13] Barr, R. E., and D. Juricic, Classroom Experiences in an Engineering Design Graphics Course with a CAD/CAM Extension, Engineering Design Graphics Journal, Vol. 62, No. 1, 1997, pp [14] Koen, B. V., Toward a Strategy for Teaching Engineering Design, ASEE Journal of Engineering Education, Vol. 83, No. 3, 1994, pp d2-6