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In the digital era, the demand for practical and efficient security systems has significantly increased, particularly in the context of access control for restricted rooms or buildings. This research aims to develop an automatic door locking system utilizing an RFID card and a NodeMCU ESP32 microcontroller integrated with Internet of Things (IoT) technology through real-time notifications using the Telegram application. The system is designed to replace conventional locking methods that often present various weaknesses, such as key loss, physical duplication, and lack of remote access capabilities. The development method employed is the Research and Development (R&D) approach, consisting of needs analysis, system design, hardware and software implementation, followed by testing and evaluation. The main components used in the system include the RC522 RFID reader for user identification, Espressif manufactures the ESP-32 microcontroller, which is equipped with Wi-Fi and Bluetooth modules to enable wireless internet connections. NodeMCU ESP32 as the control center and internet connector, a relay module as an electronic switch, and a solenoid door lock as the actuator. The results show that the system is capable of accurately reading RFID card UIDs, granting access to registered cards, activating the solenoid to unlock the door, and sending access status notifications to Telegram in an average of less than three seconds. The system also effectively denies access to unregistered cards and sends warning messages accordingly. Therefore, this system enhances the security and efficiency of room access control and has the potential to be adopted as a prototype solution in the development of smart homes or modern access control systems.

Android continues to innovate, and biometric systems particularly fingerprint sensors must operate with high efficiency. However, the main challenge lies in the communication between hardware and software, which often causes high latency, excessive power consumption, and protocol incompatibility between components. As a result, authentication speed decreases and system stability is compromised, especially on mid- to low-range devices. This study explores various implementations of Android-based fingerprint systems, focusing on how sensor modules interact with the microcontroller or Trusted Execution Environment (TEE) and the operating system through a hardware-software co-design approach to evaluate integration efficiency across all layers. The analysis reveals that conventional protocols such as Bluetooth or serial connections still cause delays, while improvements in drivers and the Hardware Abstraction Layer (HAL) can significantly reduce latency. As a solution, the researchers propose a co-design optimization approach that utilizes data flow normalization within the HAL and adopts lightweight communication protocols to accelerate the verification process. Based on the test results, this approach successfully improves efficiency—authentication time is reduced by up to 35% and power consumption decreases by approximately 15%. Therefore, the efficiency of communication between hardware and software becomes a key factor in enhancing the performance and reliability of fingerprint systems on Android devices.

Indoor positioning technology based on smartphones plays an important role in the current technological development context. Especially in applications such as warehouses, supermarkets, hospitals, or buildings. While the global positioning system (GNSS) is popular and effective outdoors, it has several limitations when operating in enclosed spaces, such as indoors, due to the complexity of these environments. Smartphones have many built-in sensors (such as light sensors, sound sensors, gyroscopes, accelerometers, and magnetic sensors) and support the connection of various types of wireless communication technologies such as Wi-Fi and Bluetooth. However, such sensors were not initially developed for positioning applications. This study addresses the positioning problem using the MUSIC technique in conjunction with the Time of Arrival (ToA) method. The effectiveness of the positioning solution is evaluated through the signal-to-noise ratio (SNR) index. The absolute error and squared error indices are evaluated through the cumulative distribution function (CDF) to indicate the effectiveness of the proposed solution. Additionally, we propose a Pedestrian Dead Reckoning method to determine a person's position in indoor environments continuously. Based on the segmentation of the moving process by turns, the direction measurements in each segment are processed using a Kalman filter, which is designed to enhance the results achieved by the system. We also discuss the challenges and some future research directions in the field of smartphone-based indoor positioning.

Stroke is a physical disability disease, which affects the upper extremity motor system. To support post-stroke motor rehabilitation, research on IoT-based elbow exoskeleton therapy devices that help elbow therapy with flexion and extension movements. The therapy device uses DS-SERVORD5160 as the main driver to provide flexible movement. By using the ESP32 microcontroller control system equipped with a Bluetooth connection that is connected via the MIT App Inventor application from a smartphone that can be done at home to increase the effectiveness of post-stroke recovery. The results of this study with low (20°), medium (40 °) and high (60 °) modes by providing a maximum load of 2 Kg. It can be concluded that the device shows stable performance in low (20 °) and medium (40 °) modes, but in testing with high mode (60 °) with a load of 2 Kg there is a decrease in servo performance which is indicated by the instability of the servo movement which shows an angle of 56 °.

The shipping industry is closely related to economic growth in various countries. This transportation is very dependent on export and import activities. As the country's economy improves, especially in Asia, the maritime transportation business in Indonesia will also develop. The pattern of sending goods via sea transportation has changed, especially in terms of bulk transportation. which demands modern technology such as automation and intelligent control systems. This research aims to design and develop Android-based spreader control using Arduino Mega 2560 on a floating ship. This project is designed to increase efficiency and ease of operation in the loading and unloading process on ships, which previously still used manual control with a remote control or joystick which had limitations such as limited visibility. In this research, the spreader control system is connected to an Arduino Mega 2560 microcontroller via the HC-05 Bluetooth module, allowing the operator to control the spreader via an Android device. Test results show that data is obtained at a distance of 1 to 13 meters, the Android-based spreader control system shows a response time ranging from 1 to 9 seconds, which shows that the system is functioning properly. At a distance of 14 to 19 meters, the response time increases to 18 seconds, indicating quite good system performance. This shows that there is quite significant latency in data transmission. However, the system still managed to carry out spreader control well. At 20 meters, the system failed to respond to the spreader control. This shows that the effective range of this Bluetooth module is below 15 meters. This research makes a significant contribution to the development of automatic control technology in the shipping industry, especially in the use of intelligent control systems integrated with mobile devices.

Technological advancements have significantly contributed to the robotics industry, yet mobility remains a challenge that can be addressed with mobile robots. In education, it is crucial to understand the basic principles of robotics and the use of related software and hardware. This research focuses on using a 4WD mobile robot as a learning tool. This robot offers flexibility and is easily controlled via a smartphone with built-in sensors. A smartphone application was developed using App Inventor, an open-source web-based development platform. The HC-05 Bluetooth module was used to connect the smartphone application with the 4WD robot. The goal of this research is to design innovative learning media to aid in understanding the concepts and control of the 4WD robot, as well as to increase students' interest and motivation in learning robotic systems. The results of the research demonstrated success in creating a 4WD robot prototype controllable via an Android smartphone. The distance between the Arduino and smartphone did not significantly affect the robot's movement, although communication was disrupted if the distance exceeded 10 meters. Directional control was achieved through the rotation of the right and left wheels, and sufficient power supply was needed to drive all wheels. Programming with C/C++ and Bluetooth communication functioned as planned. This innovative learning media is expected to help students understand and operate the 4WD mobile robot more effectively

Suara manusia memiliki banyak sekali karakteristik. Ada yang memiliki suara berat, suara yang lembut, suara yang tinggi, suara yang rendah dan lain sebagainya. Manusia dapat mengenali karakteristik suara tersebut dan mengerti hal-hal yang diucapkan. Berbagai inovasi telah dikeluarkan untuk merancang suatu kecerdasan buatan untuk mengerti arti ucapan yang diberikan oleh manusia. Hal ini menjadi ketertarikan bagi penulis untuk merancang sistem pengenalan suara. Rancangan yang dibuat penulis adalah membuat sistem pengenalan suara yang berbasis Google Speech API pada Smartphone Android untuk dapat mengendalikan sepeda motor dengan menggunakan teknologi Bluetooth HC-05 pada Raspberry Pi. Penelitian ini menggunakan 3 tahap pengujian. Pengujian pertama merupakan pengujian untuk mengetahui jarak ideal antara bibir dengan microphone pada Smartphone Android saat memberikan perintah kepada sepeda motor. Pengujian kedua dilakukan untuk mengetahui jarak ideal untuk berkomunikasi antara Smartphone Android dengan Raspberry Pi, dan pengujian ketiga adalah untuk merancang sistem keamanan tambahan dengan menggunakan sidik jari pada Smartphone Android. Hasil yang didapatkan pada pengujian pertama adalah persentase keberhasilan tertinggi berada pada jarak 5cm dengan nilai sebesar 99.17% dan tingkat terendah pada jarak 30cm antara bibir dengan microphone dengan nilai sebesar 78.33%. Pengujian kedua didapatkan hasil bahwa jarak maksimal untuk melakukan komunikasi antara Smartphone Android dengan modul Bluetooth HC-05 pada Raspberry Pi adalah sebesar 20m, lebih dari itu perangkat tidak dapat berkomunikasi. Pengujian ketiga didapatkan hasil bahwa selain sidik jari yang terdaftar maka user tidak dapat menggunakan aplikasi yang telah dirancang karena aplikasi akan melakukan looping secara terprogram.

The purpose of this thesis is to produce tangible results in providing comfort or convenience in controlling electrical appliances, including turning on or off lights at home and controlling other electrical appliances. The method used in making the Design of Control System for Electrical Equipment Using Bluetooth Based on the Atmega 328 Microcontroller is a prototype. This research method consists of several stages, library research, analytical methods, design and implementation methods. The results achieved are reducing the number of fires due to electrical short circuits and increasing aspects of comfort and convenience for users as well as people with disabilities and the elderly, who find it difficult to stand or to reach lights and the implementation of infrastructure devices, where a series of these tools can work after bluetooth devices are available in the community. android smartphones. connected to the bluetooth module connected to the arduino microcontroller. Basically, using the principle of this tool, the user must be able to operate a smartphone based on the Android operating system. The conclusion is that this equipment has been tested and can be used as a controller of power tools with a lightweight android smartphone via a Bluetooth connection without having to press the switch button.

Perkembangan teknologi semakin maju, kemajuan perkembangan ini dapat memberi keuntungan kepada masyarakat seperti perkembangan pada bidang Kesehatan seperti pada penelitian ini yang membuat aplikasi monitoring kadar gula darah dan tingkat dehidrasi dengan menggunakan MIT App Inventor. MIT App Inventor sendiri merupakan aplikasi web sumber terbuka yang dikembangkan oleh google. Dalam pembuatan aplikasi di MIT App Inventor programnya menggunakan blok-blok yang sangat mudah. Aplikasi ini dapat memonitoring kadar gula darah dan tingkat dehidrasi karena terdapat bantuan dari Bluetooth hc-05 yang berfungsi sebagai komunikasi data pengiriman data monitoring dari Arduino ke android.

The purpose of this research is to produce tangible results in providing comfort or convenience in turning on or off the night life at home everyday, especially for people who forget to turn off the lights. The method used in making microcontroller-based home lighting control using an android smartphone is. This research method consists of several stages, analysis methods, design methods, implementation testing methods, and maintenance. The results achieved are improving the aspects of comfort and convenience for agencies, where this series of tools works after bluetooth devices are available on android smartphones. connected to a bluetooth module which is connected to the Arduino microcontroller. Basically, the principle of using this tool is that users must be able to operate a smartphone based on the Android operating system. The conclusion of this research is that the Arduino-based light control device using bluetooth can fulfill its function to control the lights properly and the device is designed to be minimalist and safety so it is safe to use.