Making a Mobile Educational Robot with a Practical Approach Using Arduino

The community service held at Vocational High School (SMK) Kawung 1 Surabaya aims to make a prototype of the Mobile Robot Edu. The robot is designed in a modular form and can be programmed according to the user's wishes. The robot consists of a controller module, an ultrasonic sensor module, a line sensor module, an IR receiver module, and a Bluetooth module. So that this educational robot can be used as a line follower robot, namely with a line sensor module on the controller module, this robot also functions as a robot that can be controlled via a remote controller that emits an infrared signal that will be captured by the IR Receiver sensor that is already installed on the controller module. In addition, the robot can be controlled by a smartphone with communication via Bluetooth. Control using a smartphone can be done via the touch screen, through a voice that utilizes Google speech recognition, and through gestures that use the accelerometer sensor found on the smartphone. The outputs of this community service are the Mobile Robot Edu prototype, scientific publications, and publications in the media. So that these outputs can be used for the learning process at SMK Kawung 1 Surabaya.


Introduction
In the current era of globalization, we must have broad insight, the ability to think and be creative to adapt to the development of Information Technology (IT), and the rapid growth of technology (Jamali et al., 2013). So, schools such as Junior High School (SMP), High School (SMA), and Vocational High School (SMK) not only focus on developing scientific and theoretical knowledge but also pay attention to logical thinking processes and one's behavior. So, to keep up with these developments, the world of education is also developing. In the development of the world of education, apart from the learning method, the media used as learning aids are also growing.
Several learning methods, namely STEM (Science, Technology, Engineering, Mathematics), area curriculum based on educating students in four specific disciplines, namely science, technology, engineering, and mathematics, in an interdisciplinary and applied approach. STEM integrates it into a cohesive learning paradigm based on real-world applications (Rabiman et al., 2020). Then the method was developed into STEAM (Science, Technology, Engineering, Arts and Mathematics). STEAM Education is the same as STEM but is added about art materials. Some of ISRM 2021 254 the essential benefits for using the STEAM learning method are 1. teaching children to think critically, 2. helping to remove blockers of ideas, 3. focusing on processes that help lead to innovation, 4. teaches the power of observation from the surrounding environment and 5. Keeping up with the times With the background described above, a mobile robot is designed for low-cost education to support the learning process using STEM and STEAM methods. The robot is intended to be a modular system integrated into one and can be programmed with several robot functions, namely as a line follower robot, a robot for obstacle detection, a robot with mobile phone control, and a robot that can be controlled via an IR remote controller. The robot is designed using opensource hardware and software that can be programmed using C++ text coding or block coding using mixly. Mixly is an open-source (free) graphic visual programming language software that can code Arduino programs. Programming is elementary, which is like putting together a block or puzzle game.
Extracurricular activities are activities carried out by school students outside of the standard/main curriculum learning hours (Bakoban & Aljarallah, 2015). Students choose according to their talents and interests. Of the many extracurriculars, one of them is Robotics. Robotic activities can be carried out from elementary school to high school children. In Indonesia, many educational institutions specialize in robotic activities. Some schools include robotic actions in separate subjects.
Some of the Benefits of Learning Robotics are as follows: • Stimulates systematic and structured thinking in solving a problem.
• Improve fine motor skills in students.
• Improve Imagination skills in designing a robot because designing a robot requires creativity. • Train cooperation in groups, increase self-confidence, accept and respect opinions, and dare express or display creative ideas. • Practice patience and perseverance in doing a project.
The development of learning support equipment/modules used to improve students' motor performance has been widely developed, one of which is a robotic module for education developed by the LEGO company, but the price is costly, so schools with laboratory development funds cannot reach it. Minimal. Therefore, we propose a service with the theme of robotics for education for teachers and students of SMK Kawung 1 Surabaya in this service.

Mobile robot
Mobile Robot or mobile robot is a robot construction whose characteristic is to have an actuator in the form of a wheel to move the entire body of the robot so that the robot can move positions from one point to another. This robot car is trendy for people who are starting to learn about robots. This is because making a robot car does not require heavy physical work. To be able to make a mobile robot, minimal knowledge of microcontrollers and electronic sensors is needed (Rubio et al., 2019).
Chassis mobile robots can be easily made using plywood or acrylic to metal (aluminum). A robot car can be made as a line follower (Line Follower), a wall follower (Wall Follower), or a light follower.
Developments carried out by several national children and even high school students have tried to develop this mobile robot for several functions, including line follower robots, maze solving, and several other more unique forms such as the one currently being set by Robotics Extracurricular and several competitions were held. To test the extent to which children can explore the science of robotics. Some forms of mobile robots are shown in Figure 1.

Arduino nano
Arduino Nano is a microcontroller development circuit board based on the ATmega328P chip with a minimal form factor. Functionally it is no different from the Arduino Uno. The main difference lies in the absence of a DC power jack and the use of a Mini-B USB connector. It is called a development circuit board because it functions as a prototyping tool for microcontroller circuits. Using a development board will be easier to assemble a microcontroller-based electronic circuit than if you start making the ATMega328 from scratch on a breadboard, as shown in Figure  Arduino IDE (Integrated Development Environment) is the software used to program the Arduino board. Arduino IDE can be downloaded for free on the official website Arduino IDE (www.arduino.cc). Arduino IDE is proper as a text editor to create, edit, and validate program code and can also be used to upload program code to the Arduino board. The program code used on the ISRM 2021 256 Arduino is called the Arduino "sketch" or the Arduino source code, with the .ino source code extension (Pan & Zhu, 2018).

DC motor control
DC motor control can be done by adjusting the speed and direction of rotation. that is by combine the following two techniques: • PWM (Pulse Width Modulation) is a technique for regulating the speed of a DC motor The speed of a DC motor can be controlled by varying its input voltage. This technique generally uses PWM (Pulse Width Modulation). PWM is a technique in which the average value of the input voltage is regulated by sending a series of ON-OFF pulses. The average voltage is proportional to the pulse width, which is known as the Duty Cycle.
The higher the duty cycle, the greater the average voltage applied to the dc motor (High Speed), and the lower the duty cycle, the smaller the average voltage applied to the dc motor (Low Speed). Figure 3 illustrates the PWM technique with various duty cycles and their intermediate voltages.  Figure 4. If S1 and S3 are closed while S2 and S4 are open, the motor will rotate clockwise and vice versa. If S1 and S3 are open while S2 and S4 are closed, the motor will rotate counterclockwise. O'clock.

Line sensor
The line sensor is used to detect black or white lines. This sensor is used in line follower robots (line follower robots). The sensor consists of 2 components, namely an LED and a photodiode. The LED will emit that light using the TCR5000 sensor module. The physical form and circuit of the TCR5000 sensor are shown in Figure 5.

IR transmission protocol
The transmission protocol determines the pattern in which the modulated IR signal is converted to binary. There are many IR transmission protocols. Sony, Matsushita, NEC, and RC5 are some of the more common protocols. The NEC protocol is also the most common type in Arduino projects, so I'll use it as an example to show how a receiver converts a modulated IR signal into a binary signal. Logic '1' starts with a 562.5 s long HIGH pulse of 38 kHz IR followed by a 1,687.5 s long LOW pulse. A logic '0' is transmitted with a long HIGH pulse of 562.5 s followed by a LOW pulse of 562.5 s: Figure 6 is how the NEC protocol encodes and decodes binary data into a modulated signal. Other protocols differ only in the duration of the individual HIGH and LOW pulses.

Material and Methods
This series of community service activities are carried out based on problems that arise with partners. 4 stages of the process will accommodate some of the obstacles experienced by teachers and education personnel at SMK Kawung 1 Surabaya. The following are the stages of community service activities at SMK Kawung 1 Surabaya, namely Partner Data Analysis, Activity Mapping, EDU Mobile Robot Hardware Development Training, Software Development Training (C++ and Android) At the Partner Data Analysis stage, it can be explained that the activity is to analyze the understanding of teachers and students regarding robotics technology. After that, Activity Mapping is carried out to help resolve these obstacles/problems. At the Activity Mapping stage, the proposer discusses the schedule for mentoring activities and workshops/training to be carried out with the school (Gaddis & Halsey, 2015).
Phases 3 and 4 on EDU Mobile Robot Development Training will provide the elements of project management as a perfect activity by combining ease of use, capability, and flexibility so that users can manage teaching activities effectively and interactively. The training/workshop activity begins by giving a questionnaire about the development of robotic technology and then providing a briefing on general robotics theory and practical approaches. Learning is carried out directly in the classroom or laboratory while still implementing health protocols. Then the teaching continued by assembling the mobile robot kit provided by the team that carried out the service activities. Furthermore, an evaluation is given with a questionnaire. The description of the

Testing robot material
Materials for making mobile robots which include assembling electronic circuits and C++ software and applications using android. The block diagram of the mobile robot can be seen in Figure 8.

Line follower robot
In their application to the manufacture of line follower robots, line sensors use optical sensor components, namely infrared reflective sensors. The line sensor uses a TCR5000, which functions as a reflector that hits the robot's path. The robot's path is black and white so that the LED light emitted from the TCR5000 sensor will be reflected by the path and received by the phototransistor. The output of the phototransistor collector is in the form of a voltage. The IC74HC14, which is connected to the collector, is to correct the high and low signal conditions so that if the Arduino digital input pin reads it, it is only at level 0 and level '1'. The line sensor circuit can be seen in Figures 9 and Figure 10. The output of the sensor circuit is connected to Arduino pins A0, A1, A2, A3, and A4. The pin is configured as an input because it will be used to read changes in the condition of the sensor output, which is logically HIGH or LOW so that the sensor reading results are in the form of a 5bit binary number (A0, A1, A2, A3, A4). Then from these binary conditions, it can be used to control the direction and speed of the DC motor, as shown in Figure 11. The condition of the 5-bit binary sensor readings used to control the DC motor can be seen in Table 1. Each line sensor output condition controls the DC motor, which is implemented in the mo-torcp1()… motorcp10() function program. The implementation of the function program can be seen in Figure 12. The following explains the motorcp1() function program to control the DC motor speed and direction of rotation.
The square wave that appears on the oscilloscope screen has a time of HIGH (Th) = 1.2 ms and at LOW (TL) = 0.8 ms while the wave period is T = Th + TL = 1.2 ms + 0.8 ms = 2 ms, so the value of the duty cycle (D) and the average voltage of the square wave generated from the Arduino PWM (pulse width modulation) pin can be calculated as follows: D = (Th/H) x 100 % = (1,2/2) x100% = 60% Voltage Average2 = (Th/T) x Vmotor = (1,2/2) x5V = 3V The speed of the DC motor is affected by the voltage supplied by the DC motor; the greater the voltage, the speed of the DC motor will increase.

Mobile robot with proximity sensor
Mobile robots are designed to move autonomously and measure the distance of objects that block in front of them. So, the robot can be programmed to avoid objects that stop in front of it. The robot circuit is shown in Figure 12. The robot measures distance using the SR-04 ultrasonic sensor module. The space that has been measured using the sensor is used to make decisions in driving the DC motor, which is sent to the input of the DC motor driver IC L293D circuit (Winardi et al., 2020).

Mobile robot with proximity sensor
Mobile robots are designed to move autonomously and measure the distance of objects that block in front of them. So, the robot can be programmed to avoid objects that stop in front of it. The robot circuit is shown in Figure 12. The robot measures distance using the SR-04 ultrasonic sensor module. The space that has been measured using the sensor is used to make decisions in driving the DC motor, which is sent to the input of the DC motor driver IC L293D circuit (Winardi et al., 2020). Robot software is designed with algorithms; if the robot approaches the obstacle object at a distance of 5 cm, then the robot will avoid the obstacle.

Control mobile robot with remote controller
The infrared receiver circuit using the TSOP1838 sensor is shown in Figure 13. This sensor will receive data transmitted by the remote controller with infrared light media. Where the data transmitted is in the form of modulated numeric codes. The numeric codes received by the sensor will be amplified by the AGC (Automatic Gain Control) circuit, then filtered using a bandpass filter circuit with a cut-off frequency of 38Khz and demodulated by a demodulator circuit. This data is obtained by connecting the infrared receiver sensor, which is connected to the ATMega328 microcontroller and serially connected to the computer. Then each time the remote controller button is pressed, it will be read by the infrared sensor and then received by the microcontroller and sent serially to the computer. The results are displayed on the monitor screen.

Tool implementation
The results of implementing the tool from the training in the form of a prototype mobile robot are shown in Figure 14.

Conclusion
This Educational Mobile Robot Module is designed to meet the needs of education and training participants at SMK 1 Kawung Surabaya in the context of community service for the Science and Technology Utilization Program for the Community. Because the training participants mainly consist of students and several teachers from the Information Technology Study Program, this module is prepared with qualifications to summarize all the Mobile Robot Education field (Practical Approach Using Arduino). The presentation technique is carried out in an integrated manner without sorting based on education level. This is done to avoid repeating a topic just because the presentation is different based on the level of education. As a module, the discussion begins by explaining the objectives to be achieved and is accompanied by questions that measure the level of mastery of the material for each topic. Thus, users of this module can independently measure the level of completeness they have achieved.