Figure 1. The MDPP curriculum structure [Tsai et al. 1998]
TSAI, Jhy-Cherng1, WANG, Guo-Jen2 & CHIOU, Shean-Juinn3
250 Koukwang Road, Taichung, Taiwan, R.O.C.,
Department of Mechanical Engineering, National Chung-Hsing University
1 jctsai@mail.nchu.edu.tw
2 gjwang@dragon.nchu.edu.tw
3 sjchiou@dragon.nchu.edu.tw
Abstract: Mechatronics plays an important role in modern product design as a product often combines mechanical and electronic functions. Students majoring in mechanical engineering, however, often have some kind of fear of mechatronics as it involves electronics, sensoring technologies, signal processing, as well as control and software or firmware. As a result, very few mechanical engineering undergraduates are trained with mechatronics at school that in turn makes them even difficult to try mechatronics-related jobs in their career. This paper reports the design and implementation of a course for teaching undergraduates majoring in mechanical engineering with mechatronics via mechanical design and practice projects. This project-oriented course, named as "Design and Prototyping of Automated Systems", is part of a series of elective courses on mechanical design and prototyping for juniors and seniors. Mechatronics-related knowledge and technologies, including sensoring and signal processing, micro-computer-based control, programming languages for I/O control, and system integration, are lectured in addition to mechanical design and prototyping. This course emphasizes on hands-on practice on design and prototyping, in addition to theoretical analysis. Students in the class are required to design and implement mechatronics on their design, but not just paper work. In the past four years, students in the class have completed several prototypes of automated systems, including an automatic material storage and retrieve system (AS/RS), a rotary type storage system, an electric elevator, an anonymous guided vehicle (AGV), and an electricity-powered motor vehicle. All these prototypes are mechanical systems equipped with mechatronics, including sensoring, signal processing, as well as micro-computer-based digital control. Some cases completed in the class are also demonstrated and discussed.
Keywords: mechatronics, mechanical engineering, automated system, project-oriented
College graduated engineers are the main resource of higher-level work force for industry in Taiwan. As technologies for product design and manufacturing change and improve relatively fast, product life cycle is thus dramatically reduced. Therefore engineering college students are expected to be sharpened with product design and manufacturing knowledge at school, in addition to theoretical analysis capability. This is an important issue in particular when industry faces the increasing competition in the global marketplace nowadays. It is obvious that college curriculum and courses must be designed to meet this challenge in order to lead students to become productive engineers in their future.
In the past decades, college engineering education over-emphasized on theoretical training while paid little attention to the cultivation of students' creativity and practical experience. It has been reported that college students major in mechanical engineering (ME) were trained to become 'mechanical scientists' rather than to be 'mechanical engineers' in the past decades [Messerle, 1989; Atherton, 1990]. Side effects of such kind of training include at least, but not limited to, the followings. First, college graduates are unable to apply their knowledge learned and experience accumulated at schools to the demands of industry. Second, nor can they put their hands on practical work even they are interested in industry-oriented jobs. Third, it is difficult for industrial companies to equip themselves with better manpower, as a result. This becomes a negative cycle in particular under strong technology competition in the world marketplace. Moreover, students eventually lose their interest in mechanical engineering, one of the fundamental fields in engineering.
As Taiwan has been famous for its manufacturing industry, mechanical design and manufacturing becomes one of the most important technologies in this country. While conventional manufacturing industry in Taiwan is labor-intensive, the government has noticed in the early 1980s that automation technology will play an important role in improving this nation's industrial competence. The government, strategically, has formed a nine-year three-phase nation-wide program on developing automation technologies since then. This program is intended to improve the productivity of industry by transferring labor-intensive industries into technology-intensive and capital-intensive industries step by step. The program therefore includes both educational and research and development (R&D) sub-programs. In particular, educational institutes stressed on training students and engineers with automation-related knowledge and technologies while R&D institutes emphasized on developing kernel technologies and applications on manufacturing, business, construction, and agriculture.
Educational institutes started to organize curriculums and to design courses on automation technologies by the middle 1980s. Several curriculums on automation technologies, such as mechatronics, information technology, computer-aided engineering, manufacturing process automation and office automation, have been well formed and taught at engineering colleges in the past decade. Among these technologies, mechatronics is one of the most difficult technologies as it combines mechanical, electronic, and information technologies. It is a key kernel in automated system. Furthermore, mechatronics is also a key technology in modern product design as a product often combines both mechanical and electronic functions to make itself intelligent and smart. However, students majoring in electric or electronic engineering often pay less attention on mechatronics partially because that they usually have difficulty to get into the depth of mechanical-related knowledge and technology. On the contrary, students majoring in mechanical engineering often treat mechatronics as an advanced course as it involves electronics, sensoring and signal processing, as well as control and software or firmware engineering. As a result, very few undergraduates are trained with mechatronics at school that in turn makes them even difficult to try mechatronics-related jobs in their career.
To the above challenges, this paper reports the design and implementation of a course for teaching undergraduates majoring in mechanical engineering with mechatronics via mechanical design and prototyping projects. This project-oriented course, named "Design and Prototyping of Automated systems", is part of a series of elective courses on mechanical design and prototyping for undergraduate juniors and seniors. This course emphasizes on hands-on practice on design and prototyping, in addition to theoretical analysis. In the past four years, students have completed several prototypes of automated systems, including an automatic material storage and retrieve system (AS/RS), a rotary type storage system, an electric elevator, an anonymous guided vehicle (AGV), and an electricity-powered motor vehicle. All these prototypes are mechanical systems equipped with mechatronics, including sensoring, signal processing, as well as micro-computer-based digital control.
In our opinion a mechanical engineer should equip himself/herself with the knowledge on how to translate engineering problems and demands into functional design, followed by mechanism and geometrical design, design analysis, material selection and fabrication, assembly, prototyping, testing, adjusting, as well as tuning, refining, and trouble shooting that all involved in the design and manufacturing process. Students at school are supposed to learn, if not to experience, the process and methodology related to integrating and to testifying the entire process. This is part of the training to have students understand how to apply the knowledge and techniques learned at school to practical problems. In our department, a curriculum based on this concept has been implemented. A series of "Mechanical Design and Prototyping Projects" (MDPP) have been organized to offer students to explode to project-oriented practical problems. These courses emphasize on hands-on practical training of mechanical design and prototyping processes in addition to theoretical analysis training [Tsai & Chein 1995]. These hands-on training processes are expected to stimulate students' creativity and cumulate related knowledge in the learned process. It is also one of the goals of the MDPP courses that experience interchange through industry-supported projects will be able to provide students with more practical experience besides theoretical training in the college. Students are also expected to learn the methodology and attitude of teamwork through these processes.
The "Design and Prototyping of Automated systems" (DPAS) is one of the MDPP courses to offer students projects on design and prototyping mechanical systems or sub-systems based on automation technologies. Typical knowledge and technologies include computer-aided design, mechanism design, sensoring and control, system integration, and information technologies. Students in the class are required not only to develop the mechanical and electronic sub-systems, but also to use their creativity to think about possible applications of the developed systems. Students are teamed up and required to design and to prototype automated systems based on their own designs, but not just paper work. They are required to define their target and then taught how to search related information and to do analysis in order to complete design and to implement their goal.
As mentioned before that students have some kind of fear of mechatronics because electronics is not taught until junior class. Nor the sensoring and control courses are taught after the electronics course. It is difficult to enforce students to study mechatronics in this situation. While this can be improved if students want to implement mechatronics on their own design. Students have much stronger motivation to learn related knowledge as they have to design and implement such an automated system. It is not too difficult for instructors to lead students with such motivation that we give students suggestions that can make their system smarter and more intelligent. Students often appreciate such suggestions and comments as this makes their design better. In order to achieve better function, students then force themselves to implement mechatronics in their original design. The design then becomes students' "dream" that they want to have it come true.
However, as students have limited hands-on experience on implementing their dream, their dream needs to be modified again and again until it becomes practical. This is a several-month long step-by-step process. To have students learn related knowledge and technologies efficiently, we use the following approaches:
With the mentioned philosophy and methods, one student from each team is required to deliver a weekly progress report and/or demonstration of their project. This has shown a great success in tracking each project.
Although it is still arguing what should be taught to improve students' capability on mechanical design and manufacturing, educators and industrial representatives agreed that engineering college courses with more stress on practical training must be emphasized [Messerle 1989; Atherton 1990; Hoole 1991]. This agreement has been widely accepted in engineering colleges. For example, the Accreditation Board of Engineering and Technology (ABET) of USA has suggested that engineering departments at college should reorganize their programs such that students can be better trained with industrial experience [ABET 1995]. For mechanical engineering, courses that integrate design, analysis, and manufacturing can help students to overcome the transition from college to industry and should be included in the reorganized teaching program. Such courses will be beneficial for both college students and industry.
The MDPP curriculum was organized as shown in Figure 1, where these project-oriented classes are offered to juniors and seniors as they have completed basic required courses and certain advanced design and supporting courses. The curriculum is designed in such a way that students learned the process and related methodologies in mechanical design with hands-on experience and have a better idea how to apply what learned at school to engineering problems [Tsai et al. 1998].
Figure 1. The MDPP curriculum structure [Tsai et al. 1998]
In addition to regular mechanical design and analysis, additional material must be taught in the class as projects in the DPAS are intended for students to apply mechatronics technologies. Because mechatronics involves both hardware and software engineering, these additional material include the following items.
In the class, we encourage students to use micro-computer together with plug-in I/O cards to develop control schemes as they are commonly available, easy to program, and relatively economic. As for sensoring, we encourage students to use commonly available sensors, such as limit switches for positioning sensing, photosensors for tracking. Combining these sensors, students also learned how to do simple pattern recognition based on simple encoding and decoding techniques.
The MDPP series of projects were first offered at the department in the 1995 academic year. The DPAS class, an extension of a previous design and manufacturing project supported by the Ministry of Education, has been designed as one of the series since then. The goal of this course is to design and to prototype automated systems or subsystems such as the Automated Storage/Retrieval System (AS/RS) widely used in automated manufacturing system.
As there exist common methodologies and approaches that needed for students to complete their projects, they are organized into a series of lectures given to student in two semesters. These common methodologies and approaches include processes and steps in mechanical design as well as in prototyping are lectured in accordance to the progress of their projects. Some of these topics are lectured by faculty members of the department while some other industry-oriented topics are offered by invited industrial engineers and/or managers. Based on these common topics, it is believed that students have the chance to explode to industrial culture. Besides, the relationship between academy and industry is even strengthened.
Students enrolled in the MDPP projects are asked to form several teams with each team containing students with different specialties. Such arrangement is intended to enforce students to learn the attitude and methodology of teamwork, including brainstorming, teaming-up, and integration, through these processes. It is also one of the goals of this arrangement that experience interchange through industry-supported projects will provide students industry-style working attitude and better practical experience besides theoretical training in the college.
In the DPAS class, additional material needed for students' projects are lectured after the common lecture. As mentioned before that one student from each team, in rotation, is asked to report their weekly progress, including what they completed in the past week, what problems they had and how to solve the problems. Students are then questioned or challenged by the lecturers and/or classmates. Problems that have not yet solved are brought to the class for brainstorming. Students usually can find good solutions or alternatives as other teams have similar problems.
To evaluate project results, to explore the discrepancy, and to promote students' interest, an exhibition of students' projects is held at the end of the academic year with a contest for the best-achievement award. Faculties and industrial representatives are invited to judge the contest. All students in the department are asked to attend this exhibition and to elect another most-popular award.
This DPAS course was designed to give students extensive knowledge and practical experience on mechanism, structure, dynamic system, sensing, control, and mechatronics. Projects completed in this class include prototypes of a computer controlled AS/RS, a rotary type storage system, an electric elevator, an anonymous guided vehicle (AGV), and an electricity-powered motor vehicle. In this paper, we briefly discuss the AS/RS, the rotary type storage system, and the electricity-powered motor vehicle as examples.
The AS/RS is a simple prototype for students to understand how an industrial AS/RS functions. It contains three main modules: the storage structure module, the material pick-up and delivering module, and the management and control system. The first module is the structure providing storage space and the third module is a software system for system control and management. The second module is a moving vehicle with a platform that has an extendable manipulator for material pick-up and delivering. The vehicle moves along guided tracks while the platform can move up and down to provide another degree of motion. Figure 2 is a sketch of one of many modules developed in the DPAS class. It was designed to use two motors while provides three degree of motion via a specially designed clutch system. This device has been granted with the R.O.C. patent number 138305 in 1998.
Figure 2. The material pick-up & deliver module used in the AS/RS [ROC patent # 138305]
The rotary type storage system is another type of AS/RS. It is designed in such a way that the storage space is movable. This is in particular suitable for space-limited storage such as three-dimensional parking system. Figure 3 is a view showing the rotary storage system under testing. The system contains several storage cells that move in rotation, driven by a series of gear train and transmission chain. Positioning of these cells are sensed by photosensors and encoding/decoding techniques. It knows to rotate clock-wise or counter-clock-wise based on the shortest path selection. This is controlled by a micro-computer which also provides graphic interface showing the motion and location of each cell.
Figure 3. A rotary type storage system completed in the class under testing
Figure 4. An electricity-powered vehicle under field test.
Figure 3 is a snapshot of the electricity-powered vehicle under field test. The vehicle is a simple version using single motor to drive and a special designed steering mechanism. There are several special features implemented in this vehicle, including electronically inter-linked brake and acceleration module and modes control for starting and acceleration. Some of these features are also patent pending.
Engineering education plays an important role in the society and therefore curriculum and courses must be carefully designed to ensure that students are learning what required in the society. This paper describes how to equip students major in mechanical engineering with knowledge and skill on mechatronics, in particular their applications on automated systems. The Design and Prototyping of Automated Systems class, as a part of a series of project-oriented courses, is designed to give students more hands-on experience in mechanical design and prototyping and system integration via mechatronics. It also gives students more exploration to related knowledge in addition to theoretical training. This class has been proven a great success that students are trained not only to complete semi-industrial projects with their own design but also to learn the methods and skill for teamwork and brainstorming. It also proven that such arrangement can stimulate students' creativity as one of the projects has been granted the ROC patent and some others are patent pending.
As the department locates in Central Taiwan, the heart of mechanical industry in this nation, we strongly feel the responsibility to furnish mechanical industry with graduated students close to what they need. We also want to point out that we are unable to make the course reorganization without the right timing and environment. These include several projects supported by the Ministry of Education, industry-supported co-ops and research projects, co-operation with nearby research and development institutes, and assistance from the Center for Mechanical Design and Manufacturing and the Center for University-Industry Partnership at the National Chung-Hsing University. With the assistance from the Center for University-Industry Partnership, we will extend the scope of projects and invite industrial companies to join these projects with their engineering and financial support. We believe this can enhance the feature of the course and keep them on the right track.
The authors would like to express their gratefulness to their colleagues at the Mechanical Engineering Department of National Chung-Hsing University for their support on the MDPP courses. Funding for this program has been supported by the department and by the Center for University-Industry Partnership, funded by the Ministry of Education. Additional funding for this program has been supported by the Center for Mechanical Design and Manufacturing funded by the National Science Council, Taiwan, R.O.C. under contracts NSC85-2221-E-005-017, NSC86-2221-E-005-022 and NSC87-2218-E-005-014.