SUGISAKAMASANORI

Journal of Robotics, Networking and Artificial Life
Vol. 9(4); March (2023), pp. 337–342
ISSN (Online):2352-6386; ISSN (Print):2405-9021
https://alife-robotics.org/jrnal.html

Jonghyun Ahn
Department of Intelligent Mechanical Engineering, Hiroshima Institute of Technology, 2-1-1 Miyake, Saeki-ku, Hiroshima, 731-5193, Japan

Received 15 November 2022
Accepted 05 January 2023

Robotics education
Robotics arm design
Robotics arm control
3D printer education

In the field of robotics education, understanding the design, manufacturing, and control of robots
is an important aspect of understanding the development of robots. Therefore, various universitylevel robotics education courses have been created to cover these topics. However, students
typically learn about design, manufacturing, and control in different classes. This can potentiallylower their understanding of robotics development. There are various reasons why these topics
are taught in different classes, but the main reason is the difficulty of manufacturing.
Manufacturing education parts often requires a machine such as a CNC, and in the case of a classfor many students, it takes a lot of time to manufacture objects designed by students. Recently,
low-cost 3D printers have become available, which are considered a solution for reducing
manufacturing time. In this paper, I propose a year-round robotics class that covers design,manufacturing, and control. Then I introduce the developed 5-axis robotic arm for education,
which can be manufactured using 3D a printer, as a result of the proposed class. The evaluationof the developed arm showed that the maximum payload (with a safety factor of 2.5) was 2.2 [kg],and the maximum repeatability was ± 0.201 [mm].
© 2022 The Author. Published by Sugisaka Masanori at ALife Robotics Corporation Ltd.
This is an open access article distributed under the CC BY-NC 4.0 license(http://creativecommons.org/licenses/by-nc/4.0/).

plastic. In this case, if the class is for a large number ofstudents, there are various problems with time and cost.
This is because expensive machines such as CNCs arerequired for the manufacture of various shaped robotparts. It is not easy to prepare a large number of CNCsfor manufacturing education, so it is difficult tomanufacture various robot parts within a fixed class time.
Recently, low-cost 3D printers, which are cheaper
compared to CNCs, have been introduced into theeducation field[3],[4],[5], and manufacturing education
using low-cost 3D printers is attracting attention as asolution to these time and cost problems.
In this paper, I propose a year-round robotics class thatcovers design, manufacturing, and control. I also
introduce the developed 5-axis robotic arm, which can be

1. Introduction
As the size of the global smart robot industry grows
every year[1],[2], the importance of robotics education isincreasing. In response, many universities around theworld have prepared robotics education courses that
include design, manufacturing, and control. However,students typically learn about design, manufacturing, andcontrol in different classes, which can lead to a lack ofunderstanding of the overall flow of robot development.
There are various reasons why design, manufacturing,and control are taught in different classes, but the main
reason is the difficulty of manufacturing education. In themanufacturing education for robotics, a lot of robot parts
designed by students or supervisors are made of metal or

Corresponding author’s E-mail: j.ahn.h2@it-hiroshima.ac.jp URL: https://www.it-hiroshima.ac.jp/english/337

students will learn about the basic mechanisms of 3D
printers and how to use them. In the control education
portion of the class, the supervisor will teach students
about the basic mechanisms of motors and motor drivers,
and how to use an Arduino board for motor control.
Following the design and manufacturing education,
students will then build and evaluate their own roboticarms, including measuring the maximum payload andposition repeatability. The proposed class plan is shownin Fig. 2.
The plan of proposed robotics class is composed with28 lectures as shown in Fig.2. The supervisor explains theclass content and the basic concepts of the tools in thefirst lecture. In lectures 2 and 3, students learn basic CAD,
and then design the parts of the robotic arm in lectures 4
through 9. In lectures 10 and 11, students learn aboutbasic 3D printing, and then manufacture the designed
parts using 3D printers in lectures 12 through 19. Afterthe hardware for the robotic arm is completed, students
learn motor control programming using an Arduino
board in lectures 20 through 24, and then evaluate thedeveloped robotic arm in lectures 25 through 27. In thefinal lecture, students present their developed robotic arm.

Proposed robotics class
Education topics

DesignManufacturing

Control

3D PrinterArduinoMain tools

CAD

Experience of entire processes of robot development

Evaluation of developed robot
Fig. 1. Overview of the proposed robotics classmanufactured using a 3D printer, as a result of theproposed class.
2. Robotics Education using Robotics Arm2.1. Development of the Robotics Arm

The proposal for a robotics class that covers design,manufacturing, and control is presented in Fig.1.
In the proposed robotics class, students can experience
the entire process of robot development, including design,
manufacturing, and control, as presented in Fig.1. In thedesign education portion of the class, the supervisor willteach students how to design robotic arm parts using
CAD software. In the manufacturing education portion,

A designed robotics arm, which will be assembled using
manufactured parts produced by a low-cost 3D printer, isillustrated in Fig.3.
As illustrated in Fig.3, the designed robotics arm has 5actuators. The arm was designed based on generalarticulated robots[6],[7],[8],[9]. he first actuator is used
for yaw-axis rotation, while the second and thirdFig. 2. Plan of the proposed robotics class338

The details of selected stepper motor are shown in Table
1.
As shown in Table 1, the selected stepper motor canoutput a maximum torque of 0.4[Nm]. However, theoutput of 0.4[Nm] is not sufficient to rotate the link ofrobotics the arm. Therefore, reduction drives are required
to rotate the link of robotics arm. The design of thereduction drive is also included in the design educationof the robotics arm. The designed reduction drive isillustrated in Fig.4.
As illustrated in Fig.4, the reduction drive is designedwith a planetary gear mechanism because it is compact
and provide high power density compared to standard
parallel axis gear trains[10]. The reduction ratio ofdesigned reduction drive can be defined as follows:𝑖=Fig. 3. Overview of the designed robotics armValues

Operating voltage

9 [V] ~ 40 [V]Maximum ampere

4 [A]Maximum torque

0.4 [Nm]

Step angle

1.8 [deg.]

Weight0.28 [kg]Cost

About 20.00 dollar (Include motor driver)(1)

where za is the number of teeth of the sun gear, zc is thenumber of internal gear teeth, and ηi is the efficiency ofreduction drive.
In the designed reduction drive, za was 16, zc was 64 andηi was 0.7. Therefore, the reduction ratio i was 3.5. The

Table 1. Details of selected stepper motor
Detail2𝑧𝑎∙ 𝜂𝑖𝑧𝑎 + 𝑧𝑐

actuators are used for pitch-axis rotation. The fourthactuator is used for roll-axis rotation, and the fifth
actuator is used for pitch-axis rotation. Each actuator foraxis rotation is a stepper motor, which was chosenbecause it can output high torque and can be easily
commanded to move and hold by an Arduino and motor
driver without the need for position sensors.

Fig. 4. Overview of the designed reduction drive

Fig. 5. Parts of reduction drive and assembled 2 reduction
drive

339

Fig. 6. Designed parts of robotics arm

Fig. 8. Overview of power and communication system
diagram for manufactured robotics arm

As shown in Fig.7, the manufactured robotics arm wasassembled in the same shape as Fig.3.
2.2. Control Programming of Robotics ArmFig. 7. Overview of the manufactured robotics arm using 3D
printer

The Arduino[11] board and Arduino IDE are employed
to control the manufactured robotics arm. The Arduino
board has the Input/Output pins for sensors and actuators,
and a programable processor unit for Arduino IDE. The
power and communication system diagram to control themanufactured robotics arm is shown in Fig. 8.
As shown in Fig.8, the Arduino is connected to acomputer via USB serial, which has the Arduino IDE
installed. Students in the class use pulse signals to control
the stepper motors that are equipped at each joint of therobotics arm through the motor drivers using the Arduino.
They also control the voltage of the regulated power
supply to increase motor torque. The controlled
movement of each joint of the robotics arm can be viewed

designed reduction drive can assemble same reduction
drives as shown in Fig. 5.
The designed reduction drive can be assembled withmultiple copies of itself to increase the output torque, asshown in Fig.5.
The other parts of the designed robotic arm arepresented in Fig.6.
These parts, as presented in Fig.6, are also designed
using CAD to be manufacture by the low-cost 3D printerand linked together.
The manufactured robotics arm using a low-cost 3D
printer is shown in Fig.7.

340

Rotation

Weights
fix point

Table 2 Results of position repeatability measurement

Actuator 2Actuator 2

Joint No.

1

23

45

Average ofpositiondifference [mm]0.008

0.005

0.402

0.2530.216

on YouTube at the following URL (https://www.youtube.
com/watch?v=Mf9ZWRFVhq0).

and increases the weight if the rotation is successful. As
a result of the measurement, the measured maximum
payload (with a safety factor of 2.5) was 2.2 [kg]. The
scene of the position repeatability measurement is shownin Fig. 10.
In Figure 10, the position repeatability is measured
using a precision dial indicator, and the position
repeatability of each joint is measured 20 times. The
results of measurement are shown in Table 2.
As shown in Table 2, minimum average of positiondifference was 0.005[mm] and maximum average ofposition difference was 0.402[mm].

3. Evaluation of the robotics arm

4. Conclusion

In the lecture 24~27 (Fig.2), the students evaluate theperformance of the developed robotics arm in terms ofmaximum payload and position repeatability. The
maximum payload is measured using a weight. The sceneof maximum payload measurement is shown in Fig. 9.
To measure the maximum payload, a student in the classfixes a weight on the developed robot, rotates the actuator,In this paper, I proposed a year-round robotics class thatcovers design, manufacturing, and control, and introduce
the developed 5-axis robotic arm for education. The
participating student completed all the lecture shown inFig.2. As an evaluation of the developed robotics arm,
the maximum payload (with a safety factor 2.5) was2.2[kg] the maximum repeatability was ± 0.201[mm].
Since this class was conducted on a trial basis, it wasattended by only one motivated student. Therefore, thestudent was able to participate diligently and complete all
the content. However, the university has a diverse student
population with varying levels of motivation.
As future work, I plan to offer the proposed robotics
class to a wider student population and quantitatively
evaluate and report on any problems that arise during theclass.

Weights

Weights

Move to upside

(a)

(b)

Fig. 9. Scene of the measurement of the maximum payload(a): Scene of fix weight on the robotic arm(b): Scene of the actuator 2 rotation

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Authors Introduction
Prof. Jonghyun Ahn
He is an Assistant Professor in theDepartment of Intelligent MechanicalEngineering at the Hiroshima Institute ofTechnology in Japan. He graduated witha degree in underwater robotics from theKyushu Institute of Technology in 2017.
His research interests include robotics
education, marine robotics systems,
intelligent sensing, and underwater communication systems.

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