Self-selective multi-objective robot vision projects for students of different capabilities

Mechatronics 23 (2013) 974–986

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Self-selective multi-objective robot vision projects for students of different capabilities Yongtae Do ⇑ Major of Electronic Control Engineering, Daegu University, Gyeongbuk, 712-714, South Korea

a r t i c l e

i n f o

Article history: Received 25 April 2012 Revised 3 October 2012 Accepted 22 November 2012 Available online 3 January 2013 Keywords: Mechatronics Engineering education Term project Robot vision Students of different capabilities

a b s t r a c t Over the last decade or two, project experience has received increasing attention in engineering education. Many engineering departments now use projects as a central part of their education course. In mechatronics education, for example, the techniques and knowledge of several different disciplines need to be synergistically combined, and students acquire practical skills by participating in various interdisciplinary projects. However, it is not easy for an instructor to manage a project efficiently, particularly if the project is assigned to upper year college students because they can have significantly different levels of ability. To overcome this problem, we propose a multi-objective project scheme. A project is arranged to have multiple small objectives with different difficulty levels, and each student selects one objective that he or she thinks can be achieved – there is a trade-off between the difficulty level of an objective that a student selects and the maximum score that he or she can obtain. The instructor’s evaluation and advice can then be given to students according to their individual capabilities (which is implied by the selected objective). In this way, every student can actively participate in the project, and the approach enables most students to produce successful results. The proposed project management scheme can be implemented in a parallel or serial structure. Both structures were tried with robot vision projects for junior students majoring in Electronic Control Engineering at Daegu University, South Korea. We found that the project scheme provides enhanced engineering education as well as increased student engagement and motivation. Ó 2012 Elsevier Ltd. All rights reserved.

1. Introduction Design projects are an emphasized feature in many engineering courses [1]. An important goal of an engineering design project is to expose students to a semi-realistic situation and let them learn by actually working on their own. The Accreditation Board for Engineering and Technology (ABET) states that [2–4]: ‘‘Engineering design is the process of devising a system, component, or process to meet desired needs. It is a decision-making process (often iterative), in which the basic sciences, mathematics, and engineering sciences are applied to convert resources optimally to meet a stated objective.’’ By participating in a project, students acquire the skills of applying theoretical knowledge learned in classroom lectures to build a working system. As this experience is practical and comprehensive, it will be valuable when the students enter the work force after graduation. Walsh et al. [5] described the effect of project-based education as a ‘‘sigmoidal segue’’ between the college and industry instead of a ‘‘step function’’ interface between the two. Mechatronics is a multidisciplinary field that synergistically combines mechanical, electrical, and computer engineering [6], ⇑ Tel.: +82 53 850 6625; fax: +82 53 850 6619. E-mail address: [email protected] 0957-4158/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mechatronics.2012.11.003

and a design project is particularly important in mechatronics education. In the relevant engineering courses in many colleges, design projects are assigned to students so that they can enhance their education by realistic experience. The mechatronics project can be a simple term project such as motor controller design [7], a software-based project such as LabVIEW programming for control [8], or a complex capstone project such as building a fire-fighting robot [9]. In order for these mechatronics projects to be successful, the instructor must pay great attention to project planning by considering various issues including the design topic, objective systems, management methods, technical content, available resources, expected results, and evaluation criteria. If a project is not well planned, participating students can easily become lost and the expected results might not be obtained in time. Although there is no doubt about the importance of design projects in mechatronics education, experience has shown that there are several practical problems in project management. First, projects are often planned by focusing on target systems to be built rather than by focusing on students. If a project is planned for education purposes, the participating students should be the focus of consideration. All the factors of a project need to be adjusted so that students learn more with greater enthusiasm while working on the project. It is necessary to consider the characteristics of each

Y. Do / Mechatronics 23 (2013) 974–986

participating student, such as educational background and capabilities. If a project is planned for upper year students, most have already experienced a number of projects. Through past experience, some students have become confident about a major-related project. On the other hand, some other students might have negative experiences with project work. It is not easy to motivate all students of different levels of ability with a single project theme, but it is of great importance to make most students actively take part in a project. Second, there are problems arising from teamwork. Projects in mechatronics classes are often carried out in a team environment because it has many advantages. A complicated problem in this multidisciplinary field can be solved in less time through cooperation by the participating students. Students can see what they have completed, which usually cannot be achieved by one individual. While working in a team, students also increase their skills of communication and cooperative interaction with other members. In a survey of engineering companies across North America, teamwork was identified as one of the top three skills needed by graduating engineers [10]. However, an instructor often confronts complaints from students who feel disadvantaged by being placed in a team with weaker students. They do not understand why each member receives an equal share in the evaluation although someone did not work hard. On the contrary, students who do not have much relevant knowledge and capability confess difficulty in finding their proper role on a team. Unlike industrial situations where specialists from different backgrounds work under a leader of higher rank, students in a classroom have similar educational backgrounds but only their capabilities are different. Third, the availability of resources is sometimes ignored when an instructor plans a project. However, quickly supplying required resources to students is a practically important problem. Mechatronics design can be comparatively more costly than design projects in other fields, but a larger budget is not always provided by the department. Students almost always want more assistance from the school to build a system in a more completed form, but it is not easy to meet their demands. Occasionally, even if a sufficient budget is available, other unexpected problems related to resources may occur, e.g., a parts shortage causes delivery delays and students spend significant time trying to find the replacements. Although this is also a rewarding experience for students, the project might not be completed in time. This difficulty becomes more significant for short term projects. A solution is to increase the share of software in a project. Encouraging students to use software simulation packages, or to build a software system using computer programming languages such as C++, MATLAB, or LabVIEW brings many benefits in project-based education. In this paper, we present a project scheme that consists of multiple small objectives with different difficulty levels. Each student selects one objective to pursue. Students who do not have strong capability select an objective with a low difficulty level, while confident students tackle a more advanced objective. In this way, every student can actively participate in a project because each has an achievable objective. Teaching also becomes more effective because supervision and evaluation can be made according to each student’s selected objective. The multiple objectives can be arranged to be placed in a sequence or to be achieved in parallel. We tested both structures at the class of ‘‘Sensor Systems’’, a junior-year course in the Electronic Control Engineering Major (ECEM) of Daegu University, South Korea.

2. Background Mechatronics is no longer an emerging field of engineering. There are many mechatronic products in industry and in our daily

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lives. This makes mechatronics a popular subject in engineering education institutes worldwide. Mechatronics education has been emphasized particularly in Asian countries [11] including South Korea [12]. The ECEM of Daegu University has taught mechatronics-related technologies to students for over 20 years. In this section, we first describe the curriculum and education activities of the ECEM of Daegu University, where the project management scheme presented in this paper was implemented. Then, we review various issues in project-based education including recent efforts by other institutes. 2.1. The ECEM program of Daegu University Daegu University was founded in 1956. It is home to over 90 departments and majors including ECEM. The ECEM has educated students since 1991 and currently enrolls about 250 undergraduates and graduate students. The ECEM program is accredited by the Accreditation Board of Engineering Education of Korea (ABEEK) [13], which is similar to ABET of the United States [14]. The education at the major emphasizes design and analysis by applying the principles of engineering, basic science, and mathematics. Fig. 1 shows the curriculum of the ECEM program. To comply with the recommendations of ABEEK, a number of subjects include design projects as shown in Table 1. The education provided at the ECEM of Daegu University can be summarized as follows:  Freshman and sophomore years: The basic knowledge of electrical/electronic engineering is taught to the students in their first 2 years at the major. These subjects include introductory engineering design, computer programming, engineering mathematics, electric circuits, digital logics, technical writing, and physics. It is noteworthy that 2-year military service is compulsory for young men in South Korea, and most students perform their service after spending 1 year at college. When they return to school, many have difficulty restarting their study. Thus, some courses are arranged in the second year curriculum to help the returning students recall what they learned during freshmen year (e.g., C Language Practice, Basic Electronics Lab, and Engineering Mathematics).  Junior year: The students learn the core knowledge of electronic control including courses such as Automatic Control, Microprocessors, Power Electronics, Numerical Analysis, Instrumentation and Measurement, Sensor Systems, and Signal and Systems. A number of term projects are assigned to the students in certain subjects.  Senior year: The ECEM program teaches advanced topics and application-oriented courses such as Robotics, Artificial Intelligence, Intelligent Control, Digital Control, Digital Signal Processing, Embedded Systems, and Network for Automation. Most subjects are elective, whereas completing a capstone design is required for graduation. 2.2. Major-related extracurricular activities For students interested in participating in extracurricular activities related to their major, the ECEM supports student organizations, activities and events pertaining to the study of electronic control. Examples include the following:  Inculabs: There are unique organizations called ‘‘inculabs’’ at the Information and Communication College, to which the ECEM belongs. The inculabs were initiated through the financial support of the Korean government under the New University Regional Innovation (NURI) Program in 2004. An inculab consists of about 10 to 30 members including professors, graduate students, and undergraduate students. Members of an inculab

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Basic Engineering design

Basic

Basic Physics and

Mathematics(1)

Experiment(1)

Computer

Basic

Basic Physics and

Programming

Mathematics(2)

Experiment(2)

Technical Writing

Year 1

Circuit Theor y(1)

Digital Engineering(1)

Basic Electronics

Object oriented

Electric

Engineering

Lab.

Programming

Magnetics(1)

Mathematics(1)

C Language Practice

Circuit Theor y(2)

Electronic Circuit(1)

Digital Engineering(2)

Digital Engineering

Engineering

Electric Magnetics(2)

Lab.

Year 2

Mathematics(2) Object Oriented Language Practice

Communication

Microprocessor

Electronic Circuits(2)

Theor y

Instrumentation and

Automatic Control

Electronic Circuits

Measurement Engineering

Lab. Signal and System

Year 3 Microprocessor Application and Design

Power Electronics

Automatic Control

Sensor Systems

Numerical Analysis

System Design

Instrumentation and Measurement Capstone Design

Digital Control

Engineering Laborator y Robotics

Year 4 Digital Signal

Embedded System

Ar tificial Intelligence

Processing

Network for

Automatic Control Lab

Intelligent Control

Automation

Fig. 1. Curriculum of the Electronic Control Engineering Major (ECEM) at Daegu University.

Table 1 Subjects involving design projects at the ECEM of Daegu University. Year, semester

Subject

Credit

Share of design project in course (%)

Freshman, spring

Basic engineering design

3

100

Sophomore, fall

Digital engineering(2) Circuit theory(2)

3 3

33 33

Junior, spring

Instrumentation and measurement engineering Microprocessors Automatic control Electronic circuits(2)

3

33

3 3 3

33 33 33

Microprocessor applications and design Sensor systems Automatic control system design Power electronics

2

100

3 3

33 66

3

33

Digital control Capstone design

3 3

33 100

Junior, fall

Senior, spring

freely form teams and build hardware and software systems purely for fun, or sometimes to prepare for various contests. Activities inside an inculab mostly involve creative mechatronic designs by undergraduate students, while graduate students and professors provide advice. There are currently two inculabs at the ECEM, the Electronic Control Systems Inculab and the Intelligent Automation Inculab. No clear distinction exists between the topics of study in the two inculabs, but they are advised by different groups of professors. Each inculab has experimental facilities, and members are allowed to use the

facilities anytime (24 h a day, 7 days a week). Professors monitor inculab members closely and encourage some talented students to study further in graduate school.  Clubs: There are two major-related clubs at the ECEM, AIS and Light&7.5. The activities of the clubs are similar to those of the inculabs. However, the clubs are governed by the students. In the clubs, students select their members, whereas professors select members for inculabs. In addition, clubs are open to students of other majors such as communication engineering and computer engineering.  Samsung Software Membership: Samsung Electronics operates a college student training program [15]. They run training centers in major cities in South Korea, including Daegu, to support the creative development activities of selected students. The scope of the program is not limited to software; it also includes mechatronics such as robotic systems. A few students of ECEM, particularly those who want to join Samsung after graduation, develop practical skills in support of the company. Students participating in any of the aforementioned activities are usually highly motivated. They have their own member training programs such as workshops, seminars, tutoring, and mentorship. They share their know-how among members, and they often win prizes in internal and external contests. It is certain that these extracurricular activities bring various benefits that otherwise could not be obtained through student education in the major. However, this is one of the factors that make students heterogeneous. The students participating in these extracurricular activities are quite confident, but some others – even including those who usually get good grades in classes – often think they do not have enough practical skills for the professional world after graduation.

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2.3. Issues in project-based engineering education Project-based education has many merits in engineering education. Labenda et al. [16] pointed out two deficits in traditional lecture-based education that can be compensated by student project activities. First, knowledge transfer by vocal/visual presentation cannot achieve high efficiency of education. Learning success improves only with the practical participation of students. Second, there are practical factors that cannot be acquired in lecture, such as practice-related and socio-economic competences. In the past, instructors’ concerns in project-based engineering education were usually related to the engineering issues only. In recent years, however, there has been growing interest in other aspects of educational projects including developing efficient methods of project management and incorporating the management issue into a project scheme, devising new project topics to let engineering students think about problems of our society (from engineering perspectives), and developing better project evaluation methods. Structuring a project properly and managing it efficiently are important for achieving the intended educational goals of the project. Frequently, instructors assign a project to students and leave the students alone to solve the problems associated with the topic until a specified deadline. Students are then graded based on the reported results. However, if instructors stay outside of a project structure, the project could be difficult to complete successfully from the viewpoint of education because instructor involvement during a project affects students’ activities quite positively. For example, it has been reported that instructors, if perceived to have good working relationships both inside and outside the classroom, can help students have positive and engaging experiences while working on a project [17]. Efficient management is important for students as well. They must understand the project scope assigned by instructors, effectively analyze required tasks, and plan the timing and sequence of each task when starting a project. These activities can be outlined in a documented project management plan [18]. The preparation of a detailed plan helps students meet their design objectives successfully because failures often happen when students spend time only near the project deadline [19]. Instructors also can benefit from well-structured project planning when supervising student activities. Sustainability is another important factor to consider because an education system needs to improve itself continuously. Students can proceed to the next step and use a better approach to obtain required results after reviewing their previous step during project work. Instructors can use the results to reform the project scheme for the next group of students. A line-tracing robot project described in [20] has a typical cyclic project management structure of self-improvement, which takes the following steps: (i) plan and arrangement, (ii) practice, (iii) evaluation, and (iv) improvement from the results of last year. Most engineering education projects have been carried out within the engineering domain only with goals to help students experience practical applications of theoretical knowledge acquired in classroom lectures. Recently, however, there have been approaches to develop projects that require students to apply engineering principles to solve problems related to our society [21]. Promoting social awareness as part of educational projects can be a way to prevent engineering students from becoming technocrats who deal with machines only, without philosophy. In addition, expanding the scope of an engineering project into other outside aspects of society can be an effective method to attract prospective engineering students [22,23]. Engineering projects are usually executed in teams. There are many benefits of team-based projects, as discussed in Section 1. However, there are practical difficulties, particularly in the team’s composition and evaluation. Appropriate team composition is

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crucial to the success of teamwork, but is not easy. Often, in a team, one or two leading students do most of the project work. Communication among team members, which includes the support of weaker members by stronger ones, is expected but often does not work. One solution is accepting this as the difficulty of teambased work, and let students select teams by themselves [24]. However, in this case, weak students can have difficulty in finding a team. The drawbacks of a group with only weak students are obvious, but having only strong students in a group is equally undesirable [25]. It has been suggested in a study [26] that teams should be self-selecting according to rules that encourage their diversity. Team-forming rules can be established by considering factors such as the project objectives and the characteristics of participating students. Letting graduate students work alongside undergraduate students for a project is another method [27]. This method can be beneficial to participating undergraduate students because they can receive close guidance from graduate students who act as mentors. This method, however, can be applicable only when there are enough graduate students available with funds to support them. A comprehensive study on the methods of grouping members for a team project can be found in [28–30]. Evaluation is another difficulty that instructors encounter. Often, the same marks are given to all members of a team for promoting cooperation among team members. However, since it is practically impossible for all members to equally work, giving the same marks brings dissatisfaction to some students. Assessing individual student performance in team-based work by peer evaluation is a solution [31]. In a comparative study of different methods to assign marks to members in a team [32], it was reported that students preferred allocating individual marks proportional to the individual contributions. The individual mark for a significantly above-average contribution was limited to a certain level based on the team mark to encourage teamwork process. However, students who receive bad scores from their co-members in peer evaluation are almost always weak students. In addition, when the number of students in a team is small, a peer evaluation can be distorted by the relationships among members.

3. Multi-objective project scheme In most design projects of engineering departments, an instructor explains the outline of a project, such as the aim, approach, evaluation criteria, and time constraints, to the students at the beginning of a course. Then, the enrolled students participate in research and development, often in a team environment, to obtain the required results. Effective cooperation among team members with active attitudes is important to completing a project successfully. The instructor often mixes students of different abilities in the same team, expecting that strong students lead other members and weak students learn from stronger mates when working together on a project. However, our experience has shown that it does not work this way, particularly in junior and senior year classes where students already have quite different capabilities in their major. Paradoxically, team-based project work can be effective for freshmen or sophomores when they have similar abilities and feel rather equal. Alternatively, if a project is planned so that students produce individual outputs, the difficulty level of the project becomes an important issue. Often, instructors arrange a project with respect to the expected ability of middle-achieving students in a class. Then, however, the stronger students are not challenged by the project, and the weaker students flounder [33]. If the goal of teaching is to realize the potential of each student, a practical approach is to ensure that the objectives and evaluation methods of a project are altered appropriately according to the capability of each student.

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In this section, we present a project management scheme that has multiple objectives with different difficulty levels. The instructor introduces several objectives of a project, and each participating student selects one objective that he or she thinks can be achieved. There is a trade-off between the difficulty that students should tackle and the maximum score that they can obtain; when one pursues an objective that has the highest difficulty, it is possible to obtain the highest score available when the objective is successfully achieved. The main goal of the proposed method is for all the students participating in a project to do their best while developing their potentials for a given engineering problem. Weak students will have a rare but exciting experience of completing a project for themselves. They will apply some simple theories in textbooks to solve an easy problem. Strong students, on the other hand, will have a challenge that requires their high talents. They will have the privilege of being one of only a few in the class, who tackle practical (and difficult) problems using various learned or created techniques. Most of them, with some middle level students, are encouraged to extend their work as an open-ended project. The outcomes that we can expect from the proposed project scheme are as follows:  Active attitude toward undertaking projects.  Development of skills to formulate and solve problems by applying theories and techniques.  Increased number of students who succeed with their projects without the help of others.  Raised confidence in solving engineering problems. We found that this method of project management is practically effective for a class of students having different capabilities. The proposed method can be implemented in two ways: parallel and serial structure. 3.1. Parallel structure It is usually possible to arrange different objectives in a project theme. The different objectives involve different conditions that can be applied, or different results that can be obtained by different procedures. Students select one objective that they think they can tackle considering their confidence about relevant skills and knowledge. For example, an instructor can have students experience practical motor controller design by letting them select one of three target systems; an open-loop DC motor speed control, a stepper motor control, or a servo DC motor control [7]. These systems have different levels of complexity; weak students may want to build a simple open-loop controller while confident students may try to develop a sophisticated servo controller. Fig. 2 shows a schematic diagram of the parallel project arrangement. Multiple objectives achievable through different streams are first introduced by the instructor. Students are then instructed to survey the relevant background data and the theoretical aspects of the project topic. To make this process efficient, the instructor could provide a list of references or reading materials. After a fixed period of time, students present their survey results and make a discussion. It is worthy to note that the students’ survey results are often similar to one another. This is because what students can understand at the undergraduate level is limited, and they often refer to the same sources (e.g., internet resources or related introductory textbooks). Student discussion after the survey is thus more important than what they actually obtain from the survey because students can grasp the concept, background, and difficulty-level of the project during the discussion. The instructor sometimes needs to participate in the discussion, particularly when the discussion heads in the wrong direction. After the

discussion, each student selects an objective to pursue. For example, if three objectives are introduced like Fig. 2, a group of weak students, say GW, are expected to pursue the simplest objective O1. Students who belong to the middle group, GM, will opt for the objective of intermediate difficulty, O2. Likewise, a group of strong students, GS, will select the most difficult objective, O3. After a fixed-period of time, students report their results and the results are evaluated based on the pursued objective. This means that there is virtually no competition between students who work for different objectives. The instructor can apply different grading systems to the different objectives, and students pursuing more difficult objectives are likely to receive higher scores than those working on less difficult objectives. However, another case is also possible. This situation happens when a student who has pursued O2, for example, fails to reach the objective while a student who has pursued O1 achieves a result successfully. Or, when a student shows creativity, he or she can earn a higher score than those who work for a more difficult objective but produce a plain result. For a term project, the time allowed for the project is usually inadequate. Thus, the objectives are rather simple, and the instructor can encourage some students who show enthusiasm in performing the term project to continue their work as an openended design project after the course. Students are usually excited when they are advised to do advanced work by the instructor; this can be a kind of reward for earnest students. In the open-ended project, a number of students work in a cooperative environment to devise what they want to build based on their experiences from the term project. The instructor can be a team member; however, a significant amount of guidance is not necessary because those students who continue their work after the course are highly motivated. 3.2. Serial structure The multi-objective project scheme can be arranged in sequential steps. Each step has its own objective, and the ultimate project goal is accomplished when all the steps are completed. Fig. 3 describes a serial connection of multiple objectives. As in the parallel structure, a student selects an objective that he or she wishes to pursue. For example, when a project is divided into three steps, the students of group GW usually select the earliest step to pursue the first objective, O1. Students who belong to the middle group GM then pursue O2 using the results obtained by the students who worked toward O1. Students pursuing O2 must understand the work done for O1. Thus, informal cooperation is encouraged between the students in two adjacent groups. The strong students belonging to GS finally work to complete the project. An interesting point is that weaker students explain their methods to the stronger students in this structure. This is contrary to a general teamwork situation wherein stronger members always perform a leading role in the relationship among members. As in the case of parallel implementation, the instructor can advise a few active students to continue their work as an open-ended design project after the course. Compared to the parallel structure, the final system can be built in a more complete form when a multi-objective project is managed in the serial structure because students relay one result into the next. In addition, a student who initially wanted to pursue an objective of lower difficulty can continue to work for a more difficult objective if he or she finds the project work to be interesting. Since students are required to participate in a project during only one of the divided periods within a semester, students have less burden. This also gives an instructor a lighter workload in terms of the number of projects to monitor at the same time. However, there are also disadvantages to a serial structure. First, noticeable

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Introduction

Instructor

Survey

Presentation and Discussion

Stream I

O1

Evaluation

Demo and Report

O2

Evaluation

Demo and Report

O3

Evaluation

Demo and Report

Stream II

Students

GW

GM

GS

Stream III

Open- ended Project Fig. 2. Parallel implementation of multi-objective project scheme. GW, GM, and GS represent student groups. O1, O2, and O3 are multiple objectives with different levels of difficulty arranged by the instructor. Solid lines represent work flow, and broken lines indicate actions made by either the instructor or the students.

Instructor

Introduction

Students

Survey

Presentation and Discussion

O1

Evaluation

Demo and Report

Step I

O2

Evaluation

Demo and Report

Step II

O3

Evaluation

Demo and Report

Step III

GW

GM

GS

Open- ended Project Fig. 3. Serial implementation of a multi-objective project scheme.

results are usually found in the last step carried out by strong students because objectives in earlier steps are often preparatory to

the next step. Second, there are significant mismatches between the numbers of students pursuing different objectives. Students

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tend to select a low difficulty objective first if they are allowed to continue pursuing a higher objective. Third, a project arranged in the serial structure takes more time to complete compared to the parallel structure. Finally, there is a possibility that a link between consecutive tasks cannot be connected when all students pursuing a lower objective fail to complete their projects. To prevent this situation, the instructor needs to monitor the progress of student work as frequently as possible.

4. Practical project examples The multi-objective project scheme was implemented for term projects of a junior year course called ‘‘Sensor Systems’’. This course is the second instrumentation subject after ‘‘Instrumentation and Measurement Engineering’’ in the first semester of the junior year in the ECEM. The Instrumentation and Measurement Engineering course deals with techniques for measuring electrical quantities such as current, voltage, power, and impedance. The Sensor Systems course covers sensing devices and techniques for automated systems including robots. A majority of junior year students enroll in this 15-week course although it is an elective. The following is a week-by-week list of topics covered in the course:  Sensors and automatic systems, sensor specifications.  Sensor data processing, error, least squares fit, redundant sensor fusion.  Vision sensors, vision system structure.  Various image formats.  Digital image processing techniques.  Image segmentation, color spaces.  Camera calibration, 3D vision.  Range sensing.  Sensing rotational movement.  Sensing velocity and acceleration.  Tactile and force sensing.  Sensor networks. Before entering the final year, students need to gradually develop their ability to use the textbook theories in practical applications by performing small-scale projects. Sensor Systems is one of major courses in which such small-scale projects are performed. The students enrolled in Sensor Systems have a homogeneous education experience, but they have significantly different levels of capability after completing two and one-half years in the major. Some students have a high level of skill and have won prizes in various robotics, creative design, or software programming contests. On the other hand, there are a considerable number of weak students who have difficulty following the educational track of the major. They have low self-esteem in terms of their study, and easily give up when confronting a rather complex problem. The term projects of the Sensor Systems class are usually related to vision sensing because robots are the most popular system built by senior year students for graduation capstone design projects, and students often use a camera for the sensing of their robot. In addition, most students in the Sensor Systems class also attend the Microprocessor Applications and Design course, in which (non-vision) sensor-based automatic systems are built in team projects. In the Sensor Systems course, the main concern of the instructor is to ensure that all the enrolled students participate actively in the assigned project regardless of their level of confidence. For this reason, the two projects described in this section were carried out as individual work, and each student had no choice but working hard to get a result. Vision sensing is a good project theme because it can be easily arranged into several objectives with different levels of difficulty.

4.1. Automatic fire detection by vision sensing  Motivation: It is important for students to have a good understanding of their project topic. If they feel the topic is directly related to practical needs, they are usually more motivated. Fire detection is one of the topics that the real world needs because fire is the most common disaster. The cost due to fire is tremendous and the loss of human lives is a more tragic factor. In January 2007, for example, there were 4877 fire cases reported in South Korea, and 252 people lost their lives in a single month [34]. Currently, the most popular method of fire detection is using a smoke sensor. An electronic smoke sensor is cheap, small, and easy to use. However, a vision-based method has several practical advantages. Unlike simple electronic detectors, a vision-based method can detect fire from a distance, and scene images contain auxiliary information such as the fire’s location, size, and spread speed. Although vision-based fire detection needs high system cost due to expensive equipment, installation, and signal processing, rapid advances in the electronics/computing industry has reduced the cost problem. Students participating in the fire detection project first surveyed the relevant facts, and understood the necessity of effective vision-based fire detection techniques.  Project scheme: The visual fire detection project was managed in parallel structure with three objectives, as summarized in Table 2. After the students’ survey and discussion on the topic, each student selected an objective to pursue. O1 is the easiest and O3 is the most complex. Objective O1 involves detecting fire flames in grayscale images. No temporal features are used as the flames are detected only in still pictures. Students usually used brightness and shape features to detect flame regions. Most students who selected O1 had low confidence. So, it was important for the instructor to encourage them to proceed continuously until reaching a result, regardless of whether or not the result was good. The instructor met students at a computing laboratory for 1 h per week to advise them and check their progress, whereas the other 2 h of this three-credit course in a given week were allocated for theoretical lessons. The instructor talked to students in person, and determined what they did not know. Unsurprisingly, most of the weak students did not know how to start at first, and often stopped when a difficulty occurred during problem solving. The project did not require any particular equipment (until open-ended design) except for a PC. Thus, students could work any time, in a department computer room or at home. They could gradually learn how to build vision sensing software while performing the project. As only an intensity cue was used, it was not easy to devise a creative method, and to get a good result. In this situation, report writing was emphasized by allotting one-third of the total score on the report. Each student submits a report at the end of project, and the document is expected in the typical format for a technical writing including a project title, introduction, literature survey, methodology (including flow charts and expected output), results, analysis, summary, references, and appendices. As most students of the GW group do not prepare their reports in advance, the instructor needs to check their notes as frequently as possible, and make comments on the notes that will be converted into a completed report at a later time. Only a limited number of grayscale images containing fire flames were provided to the students, and the obtained results were evaluated by checking how effectively the flame regions could be extracted using a reasonable approach. Students pursuing O2 also processed still images to find flames. However, they used color cue, and the amount of data to process became triple (Red, Green, Blue) that of grayscale images used for O1. Three sets of images were

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Table 2 Summary of visual fire detection project. Course

 Sensor systems – Elective for the juniors of ECEM – 15 weeks long, 3 credit hours – Term project contributes 20% of the subject grading

Goal

Develop a vision sensing program that can be employed for a fire security robot system

Features

 Individual term project with a self-selective objective (O1, O2, and O3 specified by the instructor) in a parallel scheme  Period: 8 weeks (excluding mid-term exam week) after the 1st month of the semester – 2 h for theoretical lecture, 1 h for project workshop  Report submission: survey (at week 3), Final (at week 8)

Objectives

 Objective O1: find fire flame region in a given image – Target student group: weak students (GW) – Condition: limited number of grayscale still images  Objective O2: sort fire and non-fire color images – Target student group: middle students (GM) – Condition: various color image sets  Objective O3: detect fire in color video – Target student group: strong students (GS) – Condition: real-time processing of color video

Evaluation

 Different scores for different objectives (maximum scores) – O1 (15): survey (3) + method and implementation (7) + report (5) – O2 (18): survey (3) + method and implementation(10) + report (5) – O3 (20): survey (3) + method and implementation (12) + report (5)  Document submission – Format: summarized survey presentation, final report in the structure of scientific writing  Method and implementation – O1: functional (4) + reasonable method (3). – O2: functional (4) + reasonable method (3) + results for test images (3) – O3: functional (4) + reasonable method (4) + results for test video (4)

Open-ended design after the term project

 Students who are interested in the project are encouraged to continue an open-ended design – A group of volunteering students work as a team for the physical implementation of their term project during vacation – This after-semester design activity is not credited, but is supported by the department under the supervision of the instructor

prepared for students working on O2: the first set consisted of various fire scene images, the second set contained nonfire images with fire-like entities (e.g., yellow tulips, red lamp light, etc.) to trick the detection algorithm, and the third set consisted of randomly collected non-fire scene images. Each set had 60 images. During the project, only one-half of the prepared images were provided for students to develop their method using them, and the remaining images were used later for the evaluation. The most difficult objective, O3, was fire detection using color video images. Spatial features and temporal variation of fire flames were used. This is a rather complex problem, and a paper [35] was provided as a reference. Students pursuing O3 demonstrated how their system worked, and the system was checked with six fire and non-fire videos for evaluation.  Open-ended design: Since the fire detection project was a term project, it was not easy for students to build a complete system. Some students were quite interested in the project, and the instructor encouraged them to continue their project in an open-ended design. Although the open-ended project was not credited, the students were supported by the department in two ways: (i) they could use a well-equipped laboratory facility any time under their own responsibility, and (ii) they could purchase electronic/mechanical components using the department budget – the ECEM allows each faculty member to spend up to about $US 3000 per year freely on student education. A number of students (mostly from those who pursued O3) volunteered to continue their work after the course. After brainstorming, they decided to build a security robot that can find fire. A pan-tilt camera was employed, and the students implemented the video-based flame detection algorithm they developed for the term project. They also used gas, temperature, and smoke sensors to increase the credibility of fire detection. Using ultrasonic range finders, obstacles around the robot could be detected.

Wheels were driven by four DC motors, and the system’s operation was monitored and controlled using a graphical user interface (GUI). Fig. 4 shows the system that the students constructed during winter vacation (after the Sensor Systems course), which is about 2 months long. 4.2. Visual human hand detection  Motivation: Students start this project by surveying the meaning of the project topic, potential applications, and existing methods. They find that man-machine interaction is an important issue in recent trends of human-centered engineering. Students realize that humans should be placed in the center of the process when they develop techniques. The visual detection of human hands, the topic of the term project, has diverse applications. For example, a visual hand gesture recognition system provides a more natural interface to a computer-based system than widely used methods such as keyboards, mice, and joy sticks. Sign language understanding is another application of visual hand gesture recognition. Although understanding sign language is a difficult problem in machine vision, students showed high interest in the technique for assisting handicapped people. Before starting the project, students report their survey results including hand structure, modeling, vision sensing methods, and various application examples.  Project scheme: The vision-based human hand detection project was carried out as the term project for the Sensor Systems course. It has three objectives with different difficulty levels, as in the fire detection project, but the hand detection project was managed using the serial scheme. Thus, this project took longer to complete, and was started earlier. Table 3 summarizes the term project and its three objectives. The tasks performed sequentially for the three objectives are shown in Fig. 5. The first and the easiest objective, O1, is the segmentation of hand

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Ultrasonic range finder

Gas, Temperature, Smoke sensors Pan/ Tilt camera

RF transmitter

Fig. 4. Fire-detecting mobile robot constructed for open-ended student design.

Table 3 Summary of visual hand detection project. Course

Goal Features

Objectives

Evaluation

Open-ended design after the term project

 Sensor systems – Elective for the juniors of ECEM – 15 weeks long, 3 credit hours – Term project contributes 20% of the subject grading Develop a vision sensing program that can be employed for a hand-based man-machine interface  Individual term project with a self-selective objective (O1, O2, and O3 specified by the instructor) in a serial scheme  Period: 14 weeks (excluding mid- and final-term exam weeks) – 2 h for theoretical lecture, 1 h for project workshop  Report submission: survey (at the 3rd week), final (after 2 or 3 weeks of work)  Objective O1: find hand skin region in color image – Target student group: weak students (GW) – Condition: skin pixel detection in color still images  Objective O2: recognize hand pose among rock, scissors, and paper in color image – Target student group: middle students (GM) – Condition: detection of features of the hand region in still images  Objective O3: recognize hand pose among rock, scissors, and paper in color video – Target student group: strong students (GS) – Condition: real-time processing of hand motion in color video  Different scores for different objectives (maximum scores) – O1 (15): survey(3) + method and implementation(7) + report(5) – O2 (18): survey(3) + method and implementation(10) + report(5) – O3 (20): survey(3) + method and implementation(12) + report(5)  Document submission – Format: summarized survey presentation, final report in the structure of a scientific writing  Method and implementation – O1: functional (4) + reasonable method (3) – O2: functional (4) + reasonable method (3) + results for test images (3) – O3: functional (4) + reasonable method (4) + results for test video (4)  Students who are interested in the project are encouraged to continue an open-ended design – A group of volunteering students work as a team for the physical implementation of their term project – This after-semester design activity is not credited, but is supported by department under the supervision of the instructor

regions in still color images. It was assumed that students of the GW group would select O1. Their program was written in a C language function subroutine, and students who worked on the second objective, O2, employed it when they developed a program to identify a hand posture among rock, scissors, or paper. Then, students pursuing O3 finally worked to recognize rock, scissors, or paper in sequential images of a moving hand in real time. In image sequences, the tracking of a moving object uses the object’s spatial and temporal features such as position, orientation, color, velocity, and acceleration. The tracking includes procedures for prediction, detection, and verification. Target features detected in past image frames are used to predict those in current image frame. Prediction can reduce the size of a region of interest, which increases system speed and makes

the system more computationally efficient. It also increases the accuracy of detection because most unnecessary background clutter can be excluded. The detected target on a current image is verified in various ways including pattern matching. Fig. 6 shows the time required to complete the different objectives over a 15 week semester. One more week was allowed for students who pursued for O1 or O3 because they had to perform their work just before an examination (a mid-term or final examination). As in the fire detection project, the three-credit class hours of the Sensor Systems course were divided into 2 h of theoretical lessons and 1 h of project-related tutoring. The instructor checked the progress of each student and increased their speed, if necessary, by providing advices and hints. The

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Fig. 5. Tasks performed sequentially for the three objectives in the visual hand detection project.

Fig. 6. Timeline diagram of the activities for different objectives in the serial structure.

students pursuing a higher level of objective were allowed to use any result obtained at the lower level. They were even allowed to combine two or more methods reported from the lower level. While some students worked on their objective, students pursuing other objectives did not need to work. This resulted in lighter burden on the students because they worked for only a short period of time (even though they had to work intensively for the period). Students appreciated this because, as shown in Table 1, they were under the highest load in the fall semester of their junior year, during which the Sensor Systems term project was undertaken.  Open-ended design: Students who showed high enthusiasm during their projects were encouraged to continue their work after the course as an open-ended design project. Five students made a team and agreed, after discussion, to develop a robot that can play the rock-scissors-paper game with a human. The resulting robot is shown in Fig. 7. A camera was installed on the chest of the robot and a neural network was trained using the backpropagation algorithm [36] to recognize a hand pose. Three sets of ultrasonic range sensors were attached to the front of the

Fig. 7. Rock-scissors-paper gamer robot: (a) the constructed robot, (b) robotic hand poses (rock, scissors, and paper, from left to right). (c) Robot faces displayed on the monitor according to the game’s result (win, lose, draw from left to right).

robot to detect an approaching human. The robot hand was designed to have three fingers to represent the poses of rock, scissors and paper. When the instructor suggested attaching two more fingers to make the robot hand similar to a human’s, students did not agree by claiming that the number of human fingers might evolve into three if the fingers’ only function is

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Fig. 8. Project objectives and completed work: (a) fire detection project, and (b) hand detection project. In the figures, the symbol # means ‘‘the number of’’.

playing the rock-scissors-paper game. To make the game interesting, students exhibited the robot’s feeling by simulating emotional faces based on the game’s result. 5. Results In both projects described in Section 4, the project work is a minor part of the course because the term project is less than one-third of the course in terms of allocated time and awarded scores. However, students showed great interests in the project. Although the objectives were set by the instructor, students needed self-instruction to implement a particular development task for their project. Due to the unique structure of the projects, students initially asked many questions and had difficulty starting the project, but soon they headed in the right direction to reach their selected objective. Particularly, weak students who had often failed in obtaining results in the assignments and projects of other courses found themselves working actively for the objective. The two exampled projects were related to vision sensing. Although both were planned to have three objectives, they were managed using two different structures: parallel and serial. The objectives of the visual fire detection project were achieved in parallel. Most students (30 out of 33 students) completed their projects – a project was considered to be ‘‘completed’’ if a student demonstrated that his or her system worked and the final report was submitted by a due date. The most interesting result was from a student who pursued O2. He analyzed the pros and cons of different color representations for the project, and employed YIQ (Luminance, In-phase, Quadrature) color space to extract flame pixels in color images. Using 180 fire and non-fire images, his method achieved a 75% success rate. The number of students who selected O3 was only three (i.e., less than 10% of all participating students). They demonstrated that their system could distinguish between fire and non-fire videos. However, their methods were hardly different from the method of [35] that was provided as a reference. The vision-based hand detection project was performed using the serial structure. There were no clear differences among methods developed by students for O1. This was because many students who worked on O1 were weak students, and their focus was often on completing the project rather than finding a better method. On the other hand, several interesting approaches were found by students who pursued O2. One student studied artificial neural networks by himself and tried to identify hand postures by training a neural network. Although his method showed a lower success rate than a simple method based on the size and shape of the detected hand, he worked hard to learn the techniques of neural net-

works. The results obtained by the students who worked for O3 were not good in general. Although fairly robust real time hand tracking systems were constructed with a webcam, a PC and a developed algorithm, their results for hand posture classification were somewhat unstable for sequential images. For example, programs often made a decision while a hand was still moving. Three students out of five could successfully present a demonstration of their system. In comparing the parallel and serial project management structures, the overall results were not much different. About 92.5% and 90.9% of the students completed their fire detection projects managed using the parallel structure, and their hand detection projects managed using the serial structure, respectively. However, the patterns how the students selected their objectives were different. In the parallel structure, students were not allowed to change their objective in the middle of the project, and there was not much difference between the number of students who selected O1 and O2. On the other hand, in the serial management scheme, students were allowed to pursue an objective at a higher level than their initial choice. A majority of students first selected O1, and about half of them later continued to work on O2. The number of students who wanted to pursue O3 was remarkably small in both projects. Fig. 8 shows the number of students and their overall results. After the class, students assessed the course using an online questionnaire. Project experience was one of the questions in the assessment. Students rated the project experience highly, as summarized in Table 4. For the fire detection project, 32 out of 40 students voted ‘‘very good’’ or ‘‘good’’. Even better assessment result was obtained on the hand detection project: 29 out of 33 students voted positively. In both cases, only one student disliked the project (the reason is not known because the voting was done anonymously). There were other questions in the assessment, such as the teacher’s aptitude, the teaching method and efficiency, course contents, and the general level of satisfaction. The students’ voting results for these questions were quite similar to their answers about the project. Students might have a general impression about a course – if a student likes a course, then he or she may have a tendency to answer to all questions positively. If the key path to success in mechatronics is a balance between two sets of skills – modeling/analysis and experimentation/hardware implementation skills [37] – then, the term projects described in this paper were carried out successfully. Students worked hard with enthusiasm to construct a method by analyzing the given problem, and then modified their method to obtain better performance during the implementation process. As Dekker pointed out [38], engineers must go back and expand on previous

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Y. Do / Mechatronics 23 (2013) 974–986 Table 4 Student feedback on the project experience. Projects

Fire detection Hand detection

Student voting

Total number of students

Very good

Good

Fair

Poor

Very poor

23 22

9 7

7 3

1 0

0 1

40 33

References

Fig. 9. Process to achieve the objective of a project by ‘‘re-doing’’.

steps because they know the least about the problem at the beginning of a design project. Students actually experienced the ‘‘re-doing’’ process, as shown in Fig. 9, by continuously modifying their methods to achieve higher performance in both term projects. Although the objectives were proposed by the instructor, students often set their own performance criteria and tried to improve their methods continuously.

6. Conclusions We described a multi-objective project management scheme considering different levels of student ability. In conventional educational projects, a project is usually arranged by targeting the middle-level students in a class. Such an approach cannot encourage weak students or develop the potential of strong students. The proposed method, in comparison, can highly motivate students at all levels in a class using differently set objectives and evaluation factors according to the students’ levels. The project management method was tested with the term projects in a junior level course, Sensor Systems, at Daegu University. Two vision sensing projects were carried out with three objectives with different difficulty levels. A fire sensing project was performed in a parallel management structure, and a hand detection project was performed in a serial structure. Outcomes from both projects were satisfactory. Students, including weak students, were quite motivated and actively worked to achieve their project objectives. Most weak students completed their work successfully, and this allowed them increase their confidence. A disadvantage of the multi-objective project management scheme is an increased burden on the instructor. In South Korean colleges, an instructor usually takes complete charge of a course. The Sensor Systems class has been taught by a single instructor. The instructor should advise students from different groups differently, and evaluate their results using different criteria. However, it was a satisfying experience for the instructor because the instructor had more chances to talk with each student in the class. In comparison, the serial scheme is less of a burden on the instructor than the parallel scheme because the instructor needs to meet with only some of the students who are currently working on the project. Actually, the serial scheme was developed after the author found that the parallel scheme overloaded the instructor. Other more complex issues, including applying the multi-objective project management scheme to general capstone design projects and managing team-based projects with the multi-objective scheme, should be considered in future work.

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