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Multimedia Training Materials, Robot Controls, Self-paced learning, Instructor-student communication, Mechatronics
Abstract-This paper discusses the development of a multimedia training material for use at a high-level public vocational training center, run by the Employment Promotion Corporation (EPC) in Japan, and reports on the educational merits of this material. The instructional material was developed to assist trainees in acquiring programming skills needed for small robot control. It allows self-paced learning in a lab situation by means of multimedia audio and visual information, and is much more effective than the sole use of conventional textbooks in helping people working in the technical fields to understand robot motions and their control methods. Our system differs in that self-paced learning is introduced mainly to facilitate and improve the quality of the communication between the instructor and students. The response of those attending the seminar using this material shows that we have succeeded in this goal. The material's use results in increased trainee motivation, leading to enhanced learning, and suggests one direction in multimedia practices for engineering education.
Public vocational training in Japan is carried out through two distinct systems . One consists of the 270 training centers run by the 47 prefectural governments, aimed primarily at high-school graduates. The other is a nation-wide system of 70 Polytechnic Centers (10k gif) administered by the Employment Promotion Corporation (EPC) on behalf of the Ministry of Labor. While EPC has various functions, its main job is to run these centers to provide high-level vocational training for employees of small- and medium-sized companies. Of these, Chubu Polytechnic Center (47k gif), located near Nagoya City, is the largest. The Nagoya region is the site of one of Japan's major industrial centers, with many large and small companies in areas such as automobile, aircraft, electric machines, machine tools, chemical products, ceramics, textiles, etc. Here, there is a strong desire among working people, from top management to workers at the factory floor, to learn about the latest technologies and skills and channel this knowledge toward product development and in designing new production methods.
Indeed, production technology continues to advance at a rapid rate yearly, examples being the increased use of computerized automated production systems and robots in factories in recent years. The main role of Chubu Polytechnic Center is to provide high-level vocational training in such fields to employees of firms that have no in-house training facilities. The Center offers about 600 courses yearly for these engineers/technicians in the manufacturing sector in the areas of electrical engineering, electronic engineering, information technology, and mechanical engineering. A typical course runs from two to four days. The majority of training courses are structured so that trainees can start at the beginner's level and move on to more advanced levels. But there are also many who wish to acquire skills in related cross-over fields instead of merely deepening their own specialties. Interest in mechatronics, that field whose main subject is the electronic control of mechanical devices, has been particularly high in recent years. Thus, at Chubu Center we began in 1993 a mechatronics course that involves robot control, where the subjects of motors, sensors, and interface design are integrated into a laboratory course.
After conducting a few classes, we found that individual differences among the trainees in their learning abilities and previous knowledge presented an obstacle in terms of pacing the class. Such differences were related to age, experience, job types, etc., but clearly there were those who already had considerable knowledge of electronic circuitry, others who were more proficient in handling machines, and then still others without any experience in either field. (The center's policy is to accept all applicants to a course, so we were not free to arrange the classes according to individual levels.) Therefore, it was not possible to cover the material at a speed comfortable for everyone in class; those who quickly mastered the material would be waiting idly for the rest to catch up; the slow learners, on the other hand, couldn't quite keep up with the "regular" pace. (This difference sometimes amounted to half an hour, so we initially dealt with this problem by providing two instructors for a class of five.) Some trainees complained that there was not enough time within the allotted lab period to do all the assignments. When we surveyed the attendees' response, we found that many of them felt frustrated at not being able to proceed at their own learning pace.
We decided at this point that it was more important to allow each individual to learn at their own pace, rather than covering as much material as possible. Until this time, the instructor had explained the lab procedures in front of the entire class, demonstrating with an actual robot set; and this was repeated at the beginning of each assignment. Meanwhile, a Windows personal computer was provided to each trainee for robot control purposes. In order to introduce self-paced learning, we needed to provide demonstrations individually to each trainee. It seemed like a natural solution to develop a multimedia instruction software that would explain the lab objectives and give a visual demonstration of each robot control assignment on the screen of the computer provided to each trainee, and this is what we did. We have been using this instruction software in our mechatronics course since July, 1994. This paper will describe this instruction software, outline its authoring method, and report on the actual educational results using this software.
II. OUTLINE OF MULTIMEDIA SYSTEM
The instructional material and class procedures are described below.
A. Composition of instructional material
The lab set, shown in Fig. 1 (5k gif), consists of a personal computer, robot and table. We installed five units of these training sets in the lab (102k gif), one per trainee, so that they can each learn at their own pace. The personal computer has a 32-bit CPU, is installed with Windows 3.1, and equipped with a speaker, mouse, and CD-ROM drive. The instruction software is stored in the CD-ROM and accessed through the CD-ROM drive. Microsoft Windows is used for the computer's operating system, and a mouse can be used for entering commands, so that trainees with no prior computer experience would not have to spend the precious lab period learning DOS commands on the keyboard (although when writing the robot control program the keyboard must be used.) A color monitor is used to display assignment instructions, figures, and digital video images, and the speaker is used for sound and voice instructions.
The robot system consists of the robot, drive unit, and teaching box . The robot is an articulated type, servo-controlled robot manufactured by Mitsubishi Electric Corp. It is small but functionally similar to many industrial robots in common use, able to move its arm to a goal point specified by the operator. The teaching box (19k gif) is for specifying positions used in the movement to the robot, which is done by the operator by pressing the keys on the teaching box to move the robot to a goal point. By specifying multiple positions, the robot can be taught to move along a trajectory or make a movement sequence. The position data taught in this manner are stored in the drive unit's memory.
The drive unit is composed of the DC servomotor drive circuit, I/O port, teaching box interface, computer interface, and emergency stop switch and terminal. The DC servomotor drive circuit is connected to the robot via a motor power cable and motor signal cable. The I/O port is used to control the motor of the conveyor (located next to the robot for transporting the workpiece) and to receive sensor signals. An RS-232C cable connects the computer interface and computer, and sends the robot control program to the robot and returns the robot status data to the computer. When necessary, the robot can be stopped any time by using the emergency stop switch on the front panel of the drive unit. The emergency stop terminal is connected to a photo-electronic safeguard so that if the robot runs away or the trainee comes too close, the robot will automatically stop. The robot, conveyor, and sensor are placed on top of a table.
B. The instruction software
There are three types of screens: the main display, explanations, and digital video images (see Fig. 2 (2k gif)). Each trainee covers the assigned class material by switching among the screens by clicking the icons or buttons using the mouse.
When Windows is first booted up, the main display, shown in Fig. 3 (12k gif), appears on screen. (Note that the words and text on screen shown in the figures have been translated into English for presentation in this paper, but original screens and instructional software are in Japanese.) It consists of three windows: the Notepad, Terminal, and Robot windows. The Notepad is used for writing and editing the robot control program. The Terminal is used for sending this program to the drive unit via an RS-232C cable. The Robot window shows eight icons, each indicating a different robot assignment. The lab assignments include PTP (point-to-point) control, CP (continuous path) control, palletizing, I/O control using the sensor and/or conveyor, cooperative control, and interrupt control. These assignments are arranged so that the trainee moves from the easier to the more difficult ones.
At the beginning of class, the instructor uses the first assignment "Pick and Place" to explain the use of the instruction set to the class. After that, the trainees go through the assignments each at his or her own pace. First the trainee selects the "Pick and Place" assignment from the main display's Robot window. This is a PTP control operation in which the robot moves the workpiece from position 1 to position 2. When the trainee moves the cursor to the Pick and Place icon and double-clicks the mouse, the screen switches to one explaining the assignment (see Fig. 4 (23k gif)). The explanation consists of three pages: a demonstration, position setting, and a description of the procedures. When the video icon on the demonstration page is double-clicked, a digital video that illustrates the assignment ("Pick and Place" in this case) starts running (see Fig. 5 (31k gif)). The trainee can view the video as many times as he/she wishes, and can also make it stand still or speed up by clicking the stop button or sliding the track bar on screen using the mouse. This kind of function is very effective in helping the trainee understand the assignment as when it involves a robot's movement. When the ">>" button at the upper right corner in Fig. 4 (23k gif) is clicked, the screen switches to the position setting screen (Fig. 6 (10k gif)). For the "Pick and Place" assignment, the robot must be taught two positions. When the video icon on this screen is clicked, a video that shows positions 1 and 2 starts to run (Fig. 7 ( 31k gif)). After the trainee views this, he/she clicks the ">>" button to switch to the screen that describes the procedures, shown in Fig. 8 (15k gif). Here, the procedural flow of teaching the positions to the robot and writing and running the control program is described.
C. Procedural flow of lab
The trainee begins the robot control lab from the main display, shown in Fig. 3 (12k gif). On the Terminal window, he/she first erases any data that may be stored in the drive unit. Then he/she teaches the robot the two positions for "Pick and Place"; by pressing buttons on the teaching box and direct observation, the robot is manipulated in each axis direction until it reaches the two goal positions (this is called manual teaching). For this stage, the trainee can view the digital video on the position setting page to see whether the positions are correct. Each time the robot reaches the correct goal position, its coordinates are stored in the drive unit's memory. Then on the Notepad window, the trainee writes a program for the Pick and Place operation in robot language, which is an end effector level language . (The instructor explains the robot language to class at the beginning of the lab period.) The program list for Pick and Place is shown in Fig. 9 (4k gif).
After storing the program in text format, the trainee sends the control program to the drive unit using the Transfers program on the Terminal window (14k gif). When the entire program is transmitted, the robot begins the Pick and Place operation. The trainee must observe the robot during the operation and check its movements to see whether the positions "taught" and program are correct. In addition, the class is instructed at the beginning to stop the robot using the emergency stop button if it moves in an irregular manner (e.g., crushing the workpiece, hitting the table with more force than necessary, etc.) The trainee (122k gif) is free to refer back to the assignment instructions or check the procedures any time, and if any technical problems arise can always seek assistance from the instructor. Those who have completed the assignment at hand can move on to the next one.
III. AUTHORING SYSTEM
The configuration of our authoring system is shown in Fig. 10 (4k gif). It consists of a Windows personal computer connected to a video capture card, sound card, video cassette recorder, camcorder, magneto-optical drive, CD-ROM drive, and image scanner. The multimedia instruction software for robot control described above was developed by digitizing the various media and then integrating them using the computer.
1) Digitizing text, figures and photographs
The text and figures are digital to begin with since they were written or drawn using a word processing program. Photographs were digitized and incorporated by using a color image scanner. We used color figures and photographs since they are much easier for the viewers to grasp visually.
2) Digitizing sound and video
The robot movements were recorded by camcorder, and then a video cassette recorder was used for playback to make computer editing easier. The video output consists of video signals and audio signals, which were respectively digitized by means of a video capture card and sound card that were installed to the computer. In digitizing the video signals, it was necessary to control the size of the video data so that they would not take up excessive memory space. Thus, we used a small screen size of 120 pixels~160 pixels (height ~ width), 256 colors, and a frame speed of 15 fps (frames per second). Even with these restrictions, a 40-second video required 40 MB of memory so we compressed the data to one-tenths. The audio signals were also edited to take up less memory space, with a 11.025-kHz sampling frequency and 8-bit data length .
3) Software development
By using Visual C++ to write the software program for the instructional material, we were able to incorporate user-friendly features such as the use of "automatic bootup" icons for the lab assignments, or being able to use the mouse for changing "pages" of, or exiting from the explanations. This allowed those trainees unaccustomed to using Windows OS to benefit from the lab without having to learn extra computer skills. Furthermore, we made use of the Notepad, Terminal, Write, and Media Player that come with Windows and thus saved unnecessary time and effort in the software development process . The developed instruction software was stored on a magneto-optical disk and then sent to a commercial firm to make it into CD-ROM.
IV. EVALUATION RESULTS
We have conducted six training seminars as of July 1995, in which we used the multimedia instructional material; a seminar lasts three days and is attended by five trainees most of whom are employed by various manufacturers. At the end of these seminars, we asked those who attended to fill out a questionnaire to obtain their responses to the seminar.
A. Observations from the instructor' side
Before introducing the instructional material, the instructor explained the lab objectives (i.e., assignments) and procedures to the entire class at the beginning of the each assignment, and there were usually some people in the class who did the control assignments incorrectly. After the multimedia material was introduced, however, it became possible for the trainees to read the explanations or view the demonstrations on their computers repeatedly until they correctly understood the assignment. The material thus provided an environment where the trainees could each learn at his or her own pace, instead of the instructor having to set the general pace of the class. Meanwhile, from the instructor's perspective, since the assignments were explained by the computer, this saved him from having to repeatedly explain the assignment objectives and control procedures, questions on which had been fairly common before the multimedia material was introduced. This gave the instructor more time to discuss with members of the class the finer technical issues relevant to the assignment at hand, such as the trainee's approach to robot programming, or ways of designing the sensor-conveyor interface circuit, or to just have a relaxed conversation with the trainees. This in turn made it possible for the instructor to give individual guidance to match each trainee's ability, thus deriving higher educational benefits. One tangible result of introducing the instructional material was that we were able to reduce the total time allotted to the lab period from 12 to 9 hours, and at the same time increase the number of assignments from 6 to 8. Furthermore, at times, a natural cooperation took place among the trainees, with those who had finished the assignment earlier helping out the slow learners; this seemed to take place more frequently after introducing the instructional material, which led us to think that the trainee-centered approach encouraged people to take the initiative in helping fellow classmates.
This aspect of freeing the instructor from repetitious and tedious explanations so that he can provide quality instruction is an important one, we feel, but the merits gained thus would not be forthcoming if the class were to be larger than, say, ten trainees. This is because for larger classes the communication that takes place between the instructor and individual trainees would clearly be weaker, and also because the instructor would not be able to comfortably monitor the entire class to see whether everyone is carrying out the operations correctly, or to deal with accidents like short-circuits in the motor or relay wiring, etc.
The educational quality of the class ultimately depends on the instructor, on whether he/she can derive the fullest benefits from the materials provided . If, for instance, the instructor uses the same multimedia material but does not allow self-paced learning to take place, and cares little about individual communication with the class, those attending will most likely be bored with the assignments or, conversely, become frustrated from not being able to keep pace with the rest.
B. Questionnaire results
As mentioned earlier, we asked those attending the seminar to fill out a questionnaire and evaluate the course at the end (see Fig. 11 (8k gif)). We received responses from 28 people ranging in age from 20 to 51, with an average age of 30.
1) Responses on the instructional material's operability
Although the use of Windows OS is becoming fairly common among computer users nowadays, as shown in the results for Question 1, about 70 percent of those attending the course had no prior experience using Windows. We were somewhat worried, therefore, that there would be some resistance to its use. In actuality, however, the Windows setup and operating methods that we provided, as shown in Fig. 2, were readily accepted by those attending. Most of them were technically oriented people possessing a certain degree of computer literacy, which probably explains why they were able to learn the Windows operations rather quickly. Thus, if a seminar is to be held for people with no prior experience with computers, it may be a good idea to give an introductory class on Windows at the beginning.
2) Responses on the digital video
From the results to Question 2, we see that many trainees thought that "the explanations using digital video are easy to understand." This shows the effectiveness of using video images that give a realistic demonstration of the assignment on screen. As for the video's picture quality, about half of the respondents felt that it should be improved (Question 3). In fact, the digital video image of our material is inferior in picture quality to a television image; as stated earlier, in order to save on memory space and transmit data at high-speed, we compressed the data, which removes a considerable portion of the data.
3) Overall evaluation of the instructional material
Although most of the people attending the seminar had no previous learning experience using a multimedia material, over 90 percent felt that "the instructional material was useful,"(Question 4) and that they "would like to continue attending seminars using multimedia material in the future."(Question 5) These results show clearly that our multimedia instructional material and the adoption of self-paced learning were rated highly by those attending the seminar. Apart from the six regular seminars, we also conducted a few seminars in which the instructional material (with self-paced learning) was used partway through and the rest of the seminar conducted under the previous method (i.e., without the multimedia material, and the instructor giving explanations and demonstrations before class), and vice versa; the objective here was to get a comparative evaluation from those attending (of which there were 17). Here, the results show that many felt that learning took place more smoothly when the instructional material was used, and none experienced boredom.
C. Trainee comments
As stated earlier, we have conducted six seminars as of July 1995 using this instruction software and, so far, the trainees' responses have been unanimously positive. Below are some of the comments by trainees.
"It was an enjoyable experience to learn using multimedia and robots, and I was able to understand the subject very well. I definitely plan to continue attending seminars like this one in the future."
"Since I wasn't used to Windows or using the mouse, at first I felt some resistance to learning robot control and thought that I may not be able to keep pace with the seminar. It turned out very good, however, since I was able to learn at my own pace using this multimedia learning material."
"This was the first time that I ever attended a learning situation which was so well equipped with teaching materials. The assignments themselves and the instructional CD-ROM were very well thought out, and everything was spelled out for us. I felt that I learned a great deal."
"There were many convenient features, such as being able to hear the instructions repeatedly, or to carry out the actual robot teaching operation while viewing the digital video, and these helped me to go through the assignments smoothly."
"The explanation of the assignments using digital video is wonderful. If only the quality of the screen image were better..."
This paper described the design of a multimedia instructional material used in the training of robot control, and reported the evaluation results within the context of advanced vocational training. While many of the multimedia instructional materials developed so far seem to be designed to replace the instructor in his/her role within school education, ours differ in that self-paced learning is introduced mainly to facilitate and improve the quality of the communication between the instructor and students. The response of those attending the seminar indicates that we have succeeded in attaining this goal. We believe that this approach to designing multimedia materials has great creative possibilities, and can be applied to various lab situations as well as other learning situations at the university level.
The authors wish to acknowledge their colleagues at Chubu Polytechnic Center who helped in developing the multimedia instruction material described in this paper, and the many trainees who attended the robot control seminar and generously offered their constructive views. Thanks are also due to R. Takeguchi who helped in translating the paper into English.
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Tatsuya Kikuchi (65K gif) received a B.S. degree in Electronic Engineering from the Polytechnic University, Kanagawa, Japan, in 1984. From 1985 to 1991, he was a design engineer of servomotor controls. From 1992 to 1994, he was an instructor in the Department of Electronic Engineering, the Chubu Polytechnic Center. Since 1995, he has been working at the Kanto Polytechnic Center. His interests include mechatronics and multimedia computing. E-mail: firstname.lastname@example.org
Takashi Kenjo obtained a Masters Degree in 1964 and a Doctor-of- Engineering Degree in 1971 from Tohoku University. His special interest is in small precision motors and their controls on which he has written several monographs published by Oxford University Press. He has been with the Polytechnic University of Japan since 1965 and is a professor at the Electrical Engineering and Power Electronics Department.