Teaching the Practice of Mechatronics
by
Professor Hal Gurgenci
Cooperative Research Centre for Mining Technology and Equipment Department
of Mechanical Engineering,
the University of Queensland
Mechatronics is a rapidly evolving field that can roughly be defined as the design of complex products that are a synergistic integration of mechanical, electrical and electronic components. The fundamental disciplines involved are mechanics, electronics, and computer science. A mechatronic engineer has to be able to draw input from these different disciplines and therefore needs to be a good generalist and a good designer. This presentation will relate the experience in teaching Mechatronics to a composite class of 3rd and 4th year Mechanical Engineering students (1st semester, 1999). Four different tools were used:
- computer laboratory and computer tutorials using MATLAB/SIMULINK
- group projects where students designed and built systems with mechanical, electronic, and software components
- traditional teaching in the lecture theatre
- web-based material that covers the lectures as well as some extras, including self-study assignments
Introduction
This presentation will relate the experience in teaching Mechatronics to a composite class of 3rd and 4th years (1st semester, 1999).
I joined the Department of Mechanical Engineering of the University of Queensland in 1998. The subject "E4360: Power Transfer Systems" was the first subject I taught to the Mechanical Engineering students. The Handbook entry for this subject was
E4360 - Power Transfer Systems; Offered in: BE(Man & Mat), BE(Mech), BE(Mech & Sp) #6 (< 2L < 2TP) 1st Semester; Prerequisite: (E4209 or 219) Topics: Principles and practice of power systems. Mechanical, electrical, hydraulic, pneumatic and hybrid arrangements. Energy storage. Computer control
As part of the unitisation process, this subject will be combined in 2001 with another small subject into a four-unit new subject to be called Mechatronic System Design. Last year, we started reorganising the subject material in anticipation of this change.
"Mechatronic Design" is not a typical engineering subject - assuming there is one. First of all, like any other design subject, the aim is to develop those precious synthesis skills that would enable the student to consider information from many sources and assimilate and convert them to useful and tangible product blueprints. Moreover, mechatronic is an adjective that refers to an object the understanding of which requires mechanical engineering, electrical engineering, and information technology skills in various degrees. As an in-depth treatment of the whole range is clearly impossible, the aim is to equip the students with a broad foundation and the learning skills to build on that foundation on their own as they may have to in their professional future. Finally, this is a reasonably hands-on area where the practising mechatronic engineers would be expected demonstrate basic electronic and computer interfacing skills as well as mechanical design competencies.
Based on these considerations, we set ourselves the aim of designing a subject that would equip the students with the necessary skills so that they can pick and combine the most appropriate bits from these areas of mechanical engineering, electrical and electronic engineering, and computer science to design machines or components of machines that involve mechanical and electronic parts combined together under some sort of computer control.
In this paper, I will try to describe the devices we used to achieve this aim. It may be possible to generalise from this experience to generic conclusions about teaching of engineering and engineering design in particular - but this will not be done in this paper.
The use of the Web
All subject material, including lecture notes, project material, references, tutorial assignments and solutions, exam marks, etc were put on the Web. All students had access to a computer and the Web through the following means:
- Undergraduate computer laboratory of the department
- Computers available at the Colleges
- Home computers
At the beginning of the semester, every student was asked to establish e-mail contact with the lecturer. Some of the students experienced difficulties doing this, but at the end everyone did manage to send me a greeting over e-mail. I would like to believe that this made it easier for them, later when they need to, to communicate with me through e-mail.
The students were encouraged to communicate with the lecturer through e-mail. This worked very well and the questions frequently-asked during these communications and the answers were also put on the Web. The e-mail communication was especially useful concerning questions about their computer modelling work, as the computer model files could be attached to the e-mail
Learning Objectives
The objectives were announced at the beginning of the Semester:
Mechanical engineering discipline is changing very rapidly. The traditional core is still very important but, to be a good engineer these days, you need more.
One of the things you will increasingly be called to do in your future career is to design, specify, operate or maintain machines with intermeshing mechanical and electronic components. A good example is the evolution of the motor car in the last 20 years. Consider the XC Falcon of the 70s. When you lifted the hood you knew what every part was there for. Moreover, in your backyard with minimum tooling, you could do exciting (!?) things like cleaning the carby and giving it a good tune-up. Try to do that with the new cars. I do not think this is good or bad; it is simply progress.
This subject will hopefully equip you with some of the skills to enable you to work at the interface of the mechanical and electronic engineering. The topic has acquired its own buzzword in recent years: mechatronics. At the end of the semester, I cannot promise that you will be able to give a tune-up to your new Commodore but I promise that it will be an interesting journey, you will have fun and you will acquire new skills.
At the end of the semester, you should be able to answer the following questions:
- How to simulate the dynamical behaviour of engineering systems using computer tools (MATLAB/SIMULINK)?
- How to select the right sensor for the right job; How to interface sensors with machines and computers?
- How to design and control simple electro-hydraulic and electro-pneumatic systems?
- What is a PLC and why should you know about it?
- What is a DC motor? How does it work? How do you know if you need one? How do you select the right one?
- What is a AC motor? How does it work? How do you know if you need one? How do you select the right one?
You will also design and construct a simple but non-trivial mechatronic system in our new Mechatronics Laboratory (50-C403). In doing so, not only you will gain hands-on experience on nuts and bolts of mechatronics such as sensors, PLCS, A/D cards, computer interfacing, control; but also you will appreciate non-tangible but equally important aspects of engineering such as project management, teamwork and technical communications.
The expected class size was 65. At the end, due to 4th year enrolments, the actual class size turned out to be 98.
Assessment
The multiplicity of objectives was reflected in the assessment guidelines, which stated that different parts of the subject would contribute to the Final Grade as follows:
| Computer simulation of dynamic systems (using SIMULINK) | 30% |
| Design and construction of mechatronic systems (Project Work) | 30% |
| Problem solving skills using broad mechatronic knowledge (Final Exam) | 40% |
Each one of these items corresponded to a stream in the delivery subject, namely lectures and tutorials in the undergraduate computer laboratory, project work, and the material covered during the actual lectures in the classroom. The methods of delivering these three streams are described in the following sections.
Computer Simulation of Dynamic Systems
Computer software packages Matlab and Simulink were selected as analysis aids to carry out simulation studies of the design options. The majority of the students had not been exposed to this software. Therefore, two lectures were spent in introducing the software. After this brief introduction, the students were asked to practice with the software in their own time.
Temporary licenses were obtained from the distributors of Matlab/Simulink to enable us to distribute the software to the students for home study. A class room license enabled us to put the software on the 35 computers in our undergraduate computer laboratory. Every week, tutorial assignments were given that involved the creation of computer models on some of the material covered in that week. The tutorial sessions were conducted in the computer laboratory. The class was too big to fit the 35-seat computer laboratory in one sitting. Therefore, three tutorial sessions were held every week so that every student had individual access to a PC during at least one of the sessions.
The computer-related material was tested in the mid-semester examination. The exam was given in the computer laboratory, where the students were asked questions about the performance of a physical system. These questions could only be answered by creating a computer model. The students were asked to save their models on a floppy diskette and submit these diskettes with their exam papers.
Project Work
A number of project topics were tabled in the first lecture and the students were asked to register for one of these projects. Each project targeted the design and construction of a system containing mechanical, electronic, and software components. An example is given in Figure 1.
All project teams except one were assembled in the first three weeks of the semester (the target was two). For each Project, a Project Manager was appointed after the Lecturer met with the Project Team. The job of the Project Manager was to make sure that the project was completed. The Project managers emerged naturally from each team and there was no competition for that position.
The project definitions prepared by the lecturer included specific tasks for each team member. Each Project Manager was asked to propose a schedule and the budget. The schedule would assign the project tasks to individual students in the project team. The Budget would estimate the Project expenses. Every member of the project team was assigned a specific technical job through this process. The tasks for the Nutcracker Project of Figure 1 are listed in Table 1:
| Position | Job Description |
| Project Team (1) | Form the project team; Negotiate a project budget; Prepare the formal project specs; make sure the project is completed in time and in budget; prepare and make the final project presentation |
| Mechanical Design (2) | Design and construct the nutcracker structure |
| Software & Control (2) | Design and construct the electrical circuit |
| Documentation (2) | Write safety, operating and maintenance manuals; compile mechanical, electrical and software design documentation |
| Software & Control (1) | Program the low-level drivers for the computer operating system |
| Software & Control (1) | Write the operating interface |
| Industrial Design (1) | Responsible for the industrial design quality |
| Project Safety (1) | Prepare safety guidelines for project development work and monitor the adherence to these guidelines; report safety incidents |
Table 1. Projects Tasks for the Nutcracker Project
The other projects and the size for each project team are listed in Table 2:
| Project Title | Team Size |
| Pneumatically-Actuated Nut Cracker | 11 |
| Air-Driven Nut Conveyor | 14 |
| Robot-Loaded Cargo Carrier | 15 |
| Car on a Seesaw | 22 |
| Vibration Table for Bicycle Testing | 20 |
| Electronic Weighscale | 9 |
| Robot Writer | 22 |
| Inertial Navigation of a Toy Truck | 23 |
Table 2. Project Titles
Every team was allocated two hours of project construction time in the Mechatronics Laboratory, under tutorial supervision. The project material was kept in locked cabinets between sessions.
It was repeatedly stressed that the intent was to do the work as a team. The assessment rules for the projects reflected this intent:
| 60% | Lecturer's mark for the entire project; the same for each team member |
| 10% | The average mark by the entire class; the same for each team member |
| 30% | The assessment of the Lecturer and the Tutor for individual team members. |
It is seen that only 30% of the project mark represents individual performance. The other 70% is given on the basis of the team performance.
Lectures and the Final Examination
Nothing special about this stream. Every week corresponded to one chapter title on the Lecture Notes (kept on the Web). There were tutorial problem assignments after each chapter.
The students were told that the material under each chapter heading was subject to modification without notice until the day of the lecture corresponding to that chapter. Any change implemented after that date was listed on the Web page for easy reference.
Conclusions
This concludes the teaching of this subject this year. There are some changes being planned for next year to address the issues identified during the semester:
- Workshop Budget: All projects involved fabrication of mechanical components by the Engineering Workshop. The idea was to give each team only a certain amount of workshop time to make them conscious of the manufacturing cost component of their design. Next Year we will probably go for a workshop voucher system.
- Team issues: One team had complaints about some members of the team not pulling their weight - without naming them. The issue was raised after the project assessment was completed and there was nothing that could be done. 100% individual assessment was suggested by some of the students. However, I believe that team assessment has many positive features and the project assessment guidelines will probably be the same next year.