Title of the Paper - American Society for Engineering ...



Hands-On = Minds-On: Bringing Mechatronics to Life

Without Laboratory Time

Olakunle Harrison[1]

1 Abstract

Mechatronics provides an excellent opportunity to teach students problem solving skills in a multifaceted engineering context. Teaching Mechatronics without laboratory time has required some innovation and a rethinking of the way this nontraditional mechanical engineering course is taught. In this paper the author describes various approaches used in teaching this interdisciplinary course. In the first half of the semester, build-and-test exercises, referred to as Hands-On Assignments, are used to help students gain better understanding of technical concepts covered during lecture. The assignments are a worthwhile substitute for the traditional lab time. The ability of students to retain knowledge of concepts taught is considerably improved when the opportunity exists to demonstrate what has been learned. The author shares some of his experiences in developing and teaching this undergraduate mechanical engineering course.

Introduction

Early in the 1990’s Tuskegee University along with several other universities in the Synthesis Coalition, sponsored by the National Science Foundation, embarked on an engineering curriculum improvement effort that included the introduction of Mechatronics into the respective universities’ programs [1]. It was the resulting Mechatronics course and laboratory that the author inherited. Improvements and adaptations, to be discussed later, have since been made to help students get the most out of the course.

The Mechatronics course at Tuskegee University combines a treatment of basic electronic components with software control of mechanical devices and systems. For the students, this course is unlike any of the traditional mechanical engineering courses in that it provides many opportunities to learn about electronic and mechanical components and how they can be integrated with software to produce better, cost effective solutions. Because of the nature of the subject and the volume of information to be exchanged, it is crucial to memory retention that students be exposed to laboratory exercises that reflect realistic engineering practice. The demands on instructor and graduate teaching assistant time is considerably greater than in other courses because of the numerous interactions required to help students complete their assignments and grasp the material taught. But, the rewards for both instructor and student are significant.

The goals for student learning in this three-hour credit course are as follows:

• Apply knowledge of passive and active electronic components

• Understand basic concepts of digital electronics

• Control mechanical systems by interfacing sensors and software

• Become more proficient in programming as it applies to mechanical system control

• Understand fundamentals of data acquisition

The undergraduate Mechatronics course at Tuskegee is a required senior level course currently taught only by mechanical engineering (ME) faculty. However, a multidisciplinary flavor is obtained due to the fact that students in electrical and aerospace engineering (EE and AE) departments also take the course as a technical elective. Teams are formed by pairing EE students with other majors, thus providing a taste of the reality that obtains in industry. The textbook used for the course is “Introduction to Mechatronics and Measurement Systems” by M. Histand and D. Alciatore.

The grading scheme used for the course is as follows:

• Homework 15%

• Hands-on Assignments 25%

• Projects 15%

• Exams I, II, and III 10, 10, 10%

• Final Exam 15%

Innovative Methods Used in the Course

The course is taught in the Mechatronics laboratory which allows for regular classroom seating with students surrounded by workstations and project hardware. One of the author’s strategies to help stimulate and maintain student interest is the adoption of a seamless transition between the traditional lecture format and laboratory exercises and demonstrations. Thus, during a class period, students may be introduced to a theory or concept and then immediately get to see or perform a demonstration of its application. This approach engages the students considerably with the result that their minds stay on task more than in most other courses. Other methods used in the course are discussed hereafter.

1 Hands-on Assignments

Perhaps the most striking observation about student preparedness for this course is that many initially find it challenging to translate circuit diagrams into actual working circuits. Usually, the ME students are filled with trepidation that their brief encounter with electrical circuits and machines in the sophomore or junior year will not serve them well in Mechatronics. Their fears are allayed by spending the first few weeks of the semester in review of fundamentals. Build-and-test exercises, referred to as Hands-on Assignments, are utilized to help students gain a more complete understanding of the engineering principles covered in class using actual functional devices. This groundwork is crucial to understanding what lies ahead in mechatronics. These hands-on assignments differ from those of a traditional laboratory because of their brevity as well as the method by which the students go about completing the assignments. Unlike traditional laboratory exercises, students are only given a brief description of what is required. They then turn to their class notes to find answers to various problems pertaining to necessary circuit diagrams, calculations, hook-up methods, and other tasks associated with the exercise. Using this approach significantly enhances their problem solving skills because they are mentally drawn into the exercise and have to think their way through- hands-on as well as minds-on. Typical hands-on assignments are as follows:

1. Constructing Basic Circuits (Resistive circuits with incandescent lamp and switches)

2. Employing Light Emitting Diodes in Circuits (Use capacitor along with a SPDT switch to drive LED)

3. Using the Zener Diode in a Circuit (Record Zener voltage while varying source voltage)

4. Using Bipolar Junction Transistor to switch a DC motor on and off

5. Using Relays in Circuits (Use BJT to switch relay and, in turn, switch DC motor on and off)

6. Controlling a DC Motor Using the MOSFET (Add LED’s to indicate on/off status)

7. Using BJT’s with MOSFET’s for Motor Control

8. Sensing Object Presence Using an Opto-isolator

9. Determining Motor RPM Using Opto-isolator

10. Using the Operational Amplifier for Amplification

11. Computer Interfacing with Digital Input and Output (Use trainer board for I/O)

These hands-on assignments are a worthwhile substitute for the traditional lab time and go a long way in reinforcing lecture material. Most of the hands-on assignments are single purposed and can be completed during the second half of a one-hour class period. In the second half of the semester, the assignments require more time and greater effort and are treated as mini projects. The goals for all assignments center on providing students with realistic experiences that will increase their confidence in multidisciplinary problem solving.

2 Mechatronics Kits for Student Use

Students in the class are paired up and assigned a portable, take-home mechatronics kit which comprises a commercially available training board complete with basic electronic components and a multi-meter. The kit, or “lab-in-a-box”, effectively extends the time that students interact with the course material, teaching assistant, and instructor. Thus, the kit compensates for the lack of lab time. The kit includes a trainer board that consists of a solderless breadboard, a six-step voltage supply, various switches, 8 LED’s, a seven-segment LED, a potentiometers. The trainer board is placed in a padded aluminum brief case along with a multimeter and a variety of electronics components including transistors, diodes, dc motor, and stepper motor. Students are given additional components as new topics are covered in class.

Another benefit derived from giving students these kits is that they have the opportunity to conduct experiments beyond those that were assigned in class. We have had students use the kit and their newly found knowledge in Mechatronics to do proof-of-concept presentations in other engineering courses.

Although many electrical engineering students have been required to own their own kits for years, it remains a significant area of opportunity for engaging ME students taking Mechatronics and introducing much-needed excitement and a sense of purpose to the discipline.

3 Short-term Projects

The lack of adequate laboratory time has also required innovative thinking in assigned projects. Short-term design projects are assigned to help the students get relatively quick feedback both with regard to their knowledge and their sense of accomplishment. Although the more involved design projects have their place and do yield significant delight when the students finally accomplish their goals, the author finds that the typical ME student is usually in new territory when it comes to the electronics aspects of mechatronic projects. Consequently, an extended design project that requires significant mechanical construction may detract from the learning objectives and is not considered necessary to meet those objectives. Three typical projects assigned to students are as follows:

• Control of an Automatic Stapler

• Temperature Data Acquisition with LED Readout

• Model Factory Conveyor System Control

In order to save precious time, design projects involve ready-made systems that students only have to outfit with sensors and switches in order to achieve the desired functions. One such project involves an automatic stapler such as used inside photocopiers. Students are required to design a mechatronic system assuming that the stapler is operating within a copier as originally designed. Thus, students must address issues such as the maximum number of pages to be stapled, an out-of-staple or cartridge-not-present situation, initialization of the stapler ram to its top-dead-center position, time delays preceding stapling, and the sensing of paper jams in the stapler area. Opto-isolator sensors and micro-switches are used to indicate machine status. Students get to interface the stapler with a computer and are responsible for the entire circuitry. A “C” program is written to control the operation of the stapler subject to the various conditions present.

The temperature data acquisition project involves circuit construction and the necessary programming to monitor temperature variations in the laboratory. An analog-to-digital converter is used along with a PIC microcontroller (PIC 16F84) from MicrochipTM to perform the task. A two-digit seven-segment LED is thrown into the mix for temperature display. Each team’s grade on the project depends on how much of the project is completed, with an opportunity to score more than 100% for a perfect project. By far, most students strive for the perfect score.

A third project involves the use of a programmable logic controller to drive a model factory conveyor belt moving a work piece from one station to another, Fig. 1. Adequate delays are necessary for the task at each station to be completed. Pneumatic cylinders are used to simulate work performed on the work piece. Rejected workpieces are pushed onto a secondary conveyor belt that must be activated for a given length of time. Students are required to write the program to control this system.

Fig. 1: Schematic of a Model Factory Conveyor System used in PLC project.

Students’ problem-solving skills are enhanced considerably with these short-term projects. They receive feedback on their performance rather quickly, as the project results are self-evident. Their troubleshooting skills are further enhanced by the multitude of problems that crop up in their efforts to complete the projects. The problems that students encounter span selecting components, calculations, circuit construction, and programming, [2].

These relatively short-term (1-week) projects communicate the essentials of mechatronics, i.e. thinking of the system as an integrated whole with an awareness of the essential principles of operation of electronic components, and the tying of mechanical events to software programming using sensors for a more cost-effective and robust system.

The additional overhead associated with designing, building, and testing mechanical devices – tasks typically encountered in the Capstone Design course, do not present a problem in the approach described here. Yet, students still acquire significant skill sets that will be useful to them immediately upon graduating. It is expected that, after this course, the student will be better versed in the conceptual design phase of product development, be more innovative in providing solutions to technical problems in contemporary devices and products, and be better prepared for job functions such as designing test apparatus to meet some particular need.

4 Facilitating Self-directed Learning

Of all the learning people acquire in their lifetime, none is more valuable than learning how to learn on their own [3]. As educators, one of our main goals for our students is that they embrace life-long learning and develop the ability to formulate and solve problems. Mechatronics offers an excellent opportunity to reinforce practices and attitudes that will enable students to explore solutions when confronted with multidisciplinary-type problems. In teaching this course, students are nurtured and encouraged to become self-directed in solving problems. A variety of vehicles are used in this nurturing process.

Various elements of the problem-based learning teaching method are used in this course. For example, when an electronic device, say a transistor, is introduced and discussed in class, students receive copies of the manufacturer’s data sheet for the component. Using a discussion style format, students identify the relevant parameters, their meanings, maximum or minimum values and how these figure into the overall design of the mechatronic system. Consequently, students are placed in the position of the practicing engineer in industry, a situation which enhances their problem-solving skills.

Another approach that encourages self-reliance is the requirement that the student give a verbal account of the effort expended in correcting problems associated with non-working systems. Frequently, we find that students fail to employ fundamental troubleshooting strategies in trying to get their systems to function. This requirement of accountability helps students work their way through problems.

Of all the gifts that schooling can bestow upon students, nothing is more important than teaching them how to learn on their own [3]. When the teaching takes place in a familiar context, such as with smart devices and automated systems, students are empowered to learn on their own and reap benefits far beyond those available in traditional class structures. By keeping doing and thinking together [4], the approach described in this paper helps students learn about learning.

Results

The approach to teaching a 3-credit mechatronics course without the benefit of laboratory time described here promotes greater student participation in the learning process, attentiveness, and the development of more independent, critical thinking skills. The hands-on exercises help in reinforcing knowledge of the essentials of mechatronic systems, as well as to quickly point out weaknesses in student preparedness. Short-term projects help students get relatively quick feedback both with regard to their knowledge of the subject and their sense of accomplishment.

Student performance on assignments and exams has been, on average, better than in other courses that the author teaches. About 30% more students get A’s and B’s in Mechatronics. Although it is difficult to compare this course to other ME courses, a measure of positive results can be found in heightened student interest. Most students complete all assignments and projects, with some needing more than the allotted time.

Conclusion

The author’s goals for the hands-on assignments center around providing students with problem solving and engineering practice experiences that will allow each student to gain more confidence in his/her ability to solve multi-faceted problems. Furthermore, the teaching approach described here encourages self-reliance in figuring out what pieces of information are needed to solve problems and how to find that information. It is important that students be taught problem-solving skills that can be put to use rather quickly upon entering the workforce. One student talked about getting a job with a major corporation doing work associated with PLC control, a subject with which he had just become familiar during the same semester.

Overall, the author’s experience with this course has been very positive. Because of the realism of the exercises in the course and the way students are engaged, they get a true sense of accomplishment as well as the ability to make meaningful contributions to product development activities related to mechatronic systems.

References

1.

1. Hodge, H., H.S. Hinton, and M. Lightner, “Virtual Circuit Laboratory,” Journal of Engineering Education, vol. 90, no. 4, 2001, p.507.

2. Friedman, Myles, (2000), Ensuring Student Success: A Handbook of Evidence-Based Strategies, The Institute for Evidence-Based Decision-Making in Education, Inc., Columbia, South Carolina, p.155.

3. Lindeman, Eduard C., 1961, The Meaning of Adult Education, The Oklahoma Research Center for Continuing Professional and Higher Education, Norman, Oklahoma, pp.6-7.

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1 Olakunle Harrison

Olakunle Harrison is an assistant professor of Mechanical Engineering at Tuskegee University. He joined Tuskegee in 1997 and has since taught courses in mechanics, automotive systems, machine design, capstone design, mechatronics, and design for manufacturing. He received his bachelor’s degree in Mechanical Engineering from the University of Tennessee, Knoxville, in 1986 and went on to receive the master’s and Ph.D. degrees from the same university in 1989 and 1995, respectively. He currently serves as the ASME and SAE faculty advisor at Tuskegee University and is developing an Automotive Systems focused research effort at Tuskegee University. Dr. Harrison has also directed summer academic program for pre-college and entering engineering freshmen. His research interests are in automotive systems, mechatronics, engineering design, product development, and design for manufacturing and assembly. He is a registered professional engineer in the state of Alabama.

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[1] Assistant Professor, Mechanical Engineering, Tuskegee University, Tuskegee, AL 36088

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