A Robotic System for Remote Teaching of Technical Drawing

This paper describes a robotic system that supports remote teaching of technical drawing. The aim of the system is to enable a remote class of paper-based technical drawing, where the students draw the drawing in a classroom, and the teacher gives instructions to the students from a remote place while conﬁrming the paper drawing. The robotic system has a document camera for conﬁrming the paper, a projector, and a ﬂat screen to project a cursor on the paper, and a video conference system for communication between the teacher and the student. We conducted two experiments; the ﬁrst experiment veriﬁed that use of a projected cursor was useful to point the paper remotely. The second experiment was conducted in a real drawing class, and the result showed that the students had a good impression of the system.


Introduction
The COVID-19 pandemic began in early 2020 and still spreading worldwide [1].
Japan has also had a large number of cases since 2020 [2].Universities and other educational institutions have also been taking infection control measures, including changing face-to-face classes to online [3].Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) announced the requirements to the educational institutions to take appropriate measures to prevent infection and ensure learning opportunities through effective implementation of face-to-face and remote classes.Although most classes can be held online, conducting practical training classes online is difficult.There are several approaches to teach such classes online.
One approach is the virtual lab, which prepares all environments for experiments in virtual space [4].Another approach is the remote lab, where a student remotely controls equipment in a real laboratory [5].In addition, education using a telepresence robot can be used [6], where the teacher remotely controls a robot, and the robot and the students are in the same classroom.This paper adopts the third approach, where a robot is in a classroom with students, and the teacher teaches the practice through the remote-controlled robot.
Our target is a technical drawing class, and the teacher inspects each student's drawing face-to-face.Our robot has the following functions: (1) provide face-to-face communication between the teacher and the student, (2) provide a function for the teacher to confirm the student's drawing, and (3) provide a function for the teacher to point to the drawing paper.
The rest of the paper is organized as follows.First, section 2 describes the related works, such as virtual labs, remote labs, and teleoperated robots for education.
Then, in section 3, we describe the requirements and design of the proposed system and the implementation of the system.Section 4 describes the evaluation experiments and the result of the real use of the system in a class.Finally, in section 5, we describe some conclusions and future work.

Virtual and remote labs
As described in the introduction, there are several approaches to teaching practical classes online.There are at least two distinct purposes for online classes: The first one is to let a teacher teach classes remotely, and the second one is to allow students to take classes remotely.
The approach based on the virtual lab [4] achieves both purposes because this approach prepares all equipment needed for the experiment to be reconstructed in a virtual space.The virtual labs at the beginning of the 2000s were to offer multimedia content such as video clips and interactive content in addition to texts and images [7].Then the virtual labs have incorporated simulation to provide students with the same experience as a real lab.For example, Tinkercad [8] is a virtual lab environment for building electric circuits with Arduino.Virtual labs have been developed not only for the engineering field but also in other areas such as biology [9] or chemistry [10].
Besides, the remote lab is an approach for students to operate actual equipment in the laboratory remotely [5] [11], such as automation [12], chemistry [13], and physics [14].
The virtual and remote labs are often combined to provide a realistic lab experience at a low cost [15][16] [17].

Remote teaching using robots
The virtual and remote labs are approaches for students to participate in practical classes from a distance.On the other hand, remote teaching is an approach where the teacher is in a distant place and teaches students using systems such as telepresence robots.For example, Okamura and Tanaka developed a remote teaching robot system for older people to teach children [18].In addition, Zhang et al. developed a telepresence robot [19] that is not only remote-controlled by a teacher but also can detect students and navigate itself.
Telepresence robots are used especially for language teaching [20].For example, Kwon et al. developed a telepresence robot for English tutoring [6].In their work, the pedagogical effect of telepresence robots was compared with that of autonomous robots.The research suggested that telepresence robots with human teachers were preferred over autonomous robots [21].

Combination of remote labs and robots
Remote labs and robots were often combined; however, in most cases, robots were the educational materials [22][23] [24], and these works did not intend for the robots to be a media of teaching.On the other hand, as shown in the previous section, most telepresence robots for teaching did not have functions for practical training (other than language teaching, which does not need any instruments).Therefore, developing a telepresence robot for practical training that needs physical interaction should be a new attempt in the era of COVID-19.

Objectives and requirements
Our work aims to develop a telepresence robot for remotely teaching practical training.As reviewed in the previous section, there have been virtual and remote lab systems with which students can experience practical training online and telepres-ence systems that enable teachers to lecture from a distance to the students in the classroom.However, no system has enabled a teacher to train the students in a remote classroom in practical training.The virtual and remote labs are used for self-learning, but some training needs one-to-one interaction between teachers and students.Besides, the conventional telepresence robots were intended to give a lecture or interact with language learning, which cannot be used for practical training such as a laboratory experiment.This paper focuses on developing a robot for teaching a technical drawing class.
Teaching technical drawing requires interaction between a teacher and a student [25].Using computer-aided design (CAD) tools, we can relatively easily teach technical drawing online [26].However, it is said that a traditional style of technical drawing based on paper and pencil is better for developing students' skills than CAD [27].Therefore, it is important to provide a way to teach the paper-based technical drawing remotely in the COVID-19 situation.
When using telepresence robots for education, there are two possibilities of using robots: One is the case where students operate the robots remotely and the robots are in a classroom with a teacher and other students.
To realize a system to teach technical drawing using the telepresence technique, we need the following functions: • The teacher can confirm the drawing paper and drawing behavior on the paper.
• The teacher can point to the specific part of the drawing paper.
• The teacher and the student can communicate with speech and image.
All of these functions should be provided in real-time.In addition, the system should move around the classroom so that no other staff is needed to set up the system.

The task
The task conducted by the teacher using the robot is to give instructions for drawing inspection.The material is a drawing of an object as a third-angle orthographic projection, as shown in Fig. 1.The teacher gives questions asking which parts of the drawing are incorrect, and the student is told to mark the incorrect parts.
Since the supposed students of the class are beginners in design and drafting, the drawing inspection is to point out drawing errors such as shape errors and omissions of dimensions.Therefore, the robot needs to point out the errors in the drawings so that the students can intuitively understand the correction points.
For example, suppose that a dashed line is drawn for the centerline instead of a chain line.If the instructor only says orally, "Please draw a checkmark on the dashed line," students who are not familiar with the drawing rules will not understand what part is being pointed out.In the case of a person-to-person instruction, the teacher can give an instruction both verbally by saying what to do and non-verbally by pointing to the part.As another example, suppose that the dimension of a part is incorrect.If the teacher indicates face-to-face, it will be like, "This dimension here is off by X mm." while pointing to the part where the incorrect dimension is drawn.
As shown in these examples, conversations often include directive words such as "here" and "that."Therefore, to conduct this task, the teacher and student face each other, then the teacher instructs by pointing to the drawing, the student marks the drawing, and the teacher confirms the student's behavior and the marked place in real-time.

Overview of the system
Fig. 2 shows an overview of the proposed robotic system.The system is built on a mobile base, and a projector is built into the body.The mobile base is the same as the robot ASAHI [28].The projector projects the cursor on the flat screen at the system's top.A display, web camera, loudspeaker, and microphone are mounted on the system, and the document camera is mounted above the flat screen.Fig. 3 (a) and (b) show the front and side views of the system.Fig. 4 shows the student's side of the system.A student puts a piece of drawing paper on the flat screen and converses with the teacher using the screen, microphone, web camera, and loudspeaker.When the student puts the paper on the screen, the projector projects a mouse cursor from the back of the paper so that the teacher points a specific part of the paper.The document camera captures the paper from above.Fig. 5 shows the teacher's side.The teacher uses two PCs to operate the system, where one PC (the right side) is used to confirm the paper and point to the paper; another PC (the left side) is used to make conversation with the student.Specifications of the hardware are shown in Table 1.

The communication system
Fig. 6 shows the diagram of the communication system.The system is equipped with two PCs (PC1 and PC2), and the teacher uses two PCs corresponding to the two PCs of the system (PC3 and PC4).The system has two communication channels between the teacher and the student.One channel is to capture the drawing paper and point the paper (between PC1 and PC3), where the web conference system Zoom is used for bidirectional image communication.Another channel is to make a conversation between the teacher and the student (between PC2 and PC4), and we used Google Meet as the conference system.

Verification of projector-based pointing
As a first experiment, we investigated whether the use of a mouse cursor projected on the flat screen is effective or not.We employed two experimenters (experimenters A and B).One was to give participants an explanation of the experiment and help the experiment; the other one played the role of the teacher.Eight university students participated in the experiment.
The procedure of the experiment was as follows.First, experimenter A showed the participant a drawing (shown in Fig. 1) as an example and gave the participant the following instruction."This drawing is an example of a third-angle orthographic projection.Please look at the front view.It lacks a hidden line.Please mark the incorrect part using a red pen."After the instruction, experimenter A brought the participant to the robot and put the second drawing shown in Fig. 7 on the flat screen of the robot.
Next, experimenter B talked with the participant through the robot.First, experimenter B instructed the participant to confirm the drawing for one minute.After that, experimenter B gave the following four tasks: 1 The dimension R5 is a diameter in the front view, which should be a radius.
Please mark this part.
3 In the top view, the dimensions of the holes are incorrectly written, which should be 2 × ⊘15.Please mark this part.4 The centerlines are drawn as dashed lines in the top view, which should be chain lines.Please mark these parts.
We prepared two conditions: with and without a mouse cursor projected on the drawing.In the "with cursor" condition, a mouse cursor was projected from the back of the drawing paper (as shown in Fig. 4(b)), while no cursor was used in the "without cursor" condition.The order and combination of the four tasks and the conditions were randomized.
After the session, the participants compared two conditions.They evaluated the difference using a seven-grade Likert scale, where -3 is "the second condition was much more difficult than the first one to understand," and 3 is "the second condition was much easier than the first one to understand."Since the order of the tested conditions is randomized, we converted all the data so that the "with cursor" condition came after the "without cursor" condition.In addition, we asked the participants to write the reason for the evaluation.
Table 2 shows the evaluation result.As explained above, a positive number indicates that the participant evaluated the "with cursor" condition better than the "without cursor" condition.The average of the grade points is 1.1.We conducted the t-test, and the result was t = 2.71 and p-value=0.024,which showed the "with cursor" condition was evaluated significantly better than the other condition.

Evaluation of the total system
The second experiment was conducted within an actual class of technical drawing at Osaka Institute of Technology.In this class, each student drew a drawing of the specified object.After finishing the drawing, the student moved in front of the robot and put the drawing on the flat screen.Then the student and the teacher began a session.After the session, the students answered a questionnaire.The students and the teacher were in different rooms.
The questionnaire had three questions, (1) This robotic system was useful for training, (2) This robotic system was easy to understand, and (3) It was fun to use this system.The students answered these questions on a five-grade Likert scale, from "5: Strongly agree" to "1: Strongly disagree."Forty-nine students participated in the experiment.The result of the questionnaire is shown in Table 3.This result shows that the students felt that the robotic system was somewhat useful, easy, and fun.
We gathered other opinions from the participants.One opinion said that this system was good because the student did not need to see the drawing upside down, which happened when the student and the teacher faced each other so that the teacher saw the drawing from the correct orientation.

Actual use in the class
The proposed system was used in actual classes at Osaka Institute of Technology.
First, we operated the robot in the class on April 15th, 2021.Since this was the first time the robot was used, the inspector, who played the role of a teacher, inspected the drawing from a few meters away from the robot to be able to respond immediately in case of any trouble.
In 2022, face-to-face classes were held every week from April 21st to June 2 nd (14 classes).The system was used in 8 out of 14 classes.Although the number of participants varied from class to class, about 50 to 100 participants took the robot inspection in each class.A problem in the beginning was that there was only one robot, so the students needed to wait for inspection because most of the students finished their drawings at a similar time.Therefore, we added two more learning support robots later to relieve congestion.
We introduced a reservation system for drawing inspection.After finishing the drawing, the students reserved inspection using the reservation system.When the system called a student, that student went to the robot to get his/her drawing inspected.The reservation system was based on Microsoft Teams, in which a student filled his/her student ID in the Excel worksheet in Teams class.We did not use an original reservation system mainly for security reasons.There were several troubles in operation using the reservation system and the robots.We called out to the students by their numbers for their turn, but some students did not notice the call because they concentrated on the drawing so deeply.However, as a result, the inspection proceeded smoothly with the three robots.
In the last session, the inspection was performed completely remotely from another room.The operation was the same as in the same room, and we encountered no problems in the class.

Conclusion
We described a teleoperated robotic system for a remote class of technical drawing.
The proposed system aims for a teacher to give instructions on paper-based technical drawing to the students in a classroom.The robot equips with a document camera to capture the student's drawing paper, a flat screen, and a projector to project a cursor on the paper, as well as an online meeting tool for communication between the teacher and the student.From the experimental result, we confirmed that projecting a cursor on the paper using a projector is useful for a teacher to give instructions.
The students' opinions in the actual drawing class revealed that the system was actually useful in a class.
The contribution of our work is twofold.First, it enabled the teacher in a remote site to point to a part of the paper to enhance the interaction.If we project the cursor upside, the cursor may be occluded by hands or arms on the paper.Second, the developed system enabled both the student and the teacher to view the paper from their own viewpoints.When a student and a teacher interact face-to-face, the paper from one side is inevitably upside-down.
In the experiment, we did not use the mobility of the robot.Considering the actual use-case of the system, we need to convey the system from classroom to classroom, which needs another staff at the location if the system has no moving ability.Therefore, we think that the moving ability is important.In fact, we conducted another experiment and confirmed that the operator could drive the robot between two classrooms.
In addition to the current functionality of the robot, we are planning to add a few more functions to the robot, such as a robot avatar [28][29] for communication aid and a pen plotter to enable the teacher to draw lines on the paper.

Figures
Figures

Figure 1 Figure 2
Figure 1 An example of a drawing material.

Figure 3
Figure 3 Overview of the proposed system

Figure 6 A
Figure 6 A schematic diagram of the communication system.

Figure 7
Figure 7 The drawing used in the experiment.

Table 2
Result of verification experiment of "with cursor" condition

Table 3
Result of the questionnaire in the second experiment