Cost-Effective and Low Power IoT-Based Paper Supply Monitoring System: An Application Modeling Approach  
[PERSON]  
1  
[PERSON] [PERSON]  
Attraphongse Taparugssanagorn  
Attarbonse Taparugssanagorn  
path of connection, and relationships between objects. The two approaches have the same main components, i.e., embedded devices, network protocols, the Internet, cloud services, and real-time operating systems (RTOS) [2]. Embedded devices are based on microcontrollers that run software. Network protocols such as MQTT, Transmission Control Protocol (TCP)/Internet Protocol (IP), and Web sockets are used to exchange information. The cloud provides computing resources and space for storing data. [PERSON] et al. propose a system for measuring, monitoring, and controlling washroom dispensers and products [3]. When a toilet paper dispenser or soap dispenser reaches a low level, janitors are alerted to refill the dispenser. A PC, data communication unit, and washroom monitoring system are included in the system. [PERSON] et al. propose an instrumented toilet roll holder [4]. The toilet roll holder records how much toilet paper is on the roll in use and sends the data to an online database. The authors constructed the toilet roll holder using the Electric Imp cloud service and an embedded hardware and software platform featuring an infrared sensor to detect the amount of paper on the roll. However, these authors do not optimize the power consumption of the system. Similarly, [5; 6; 7] created IoT-based hygiene monitoring systems for public toilets using various types of sensors. However, none of these researchers have explored power consumption. The Kloala Team [8] propose a real-time monitoring IoT gadget called Kloala that provides statistics and information about toilet paper usage. The main feature of this project is a real-time monitoring function that allows users to use a smartphone to check how much toilet paper is still on the roll. The Kloala device is placed above a toilet paper roll with different attachments and measures the distance to the roll using a laser distance sensor. The smartphone app displays the actual toilet paper level, allowing the user to monitor storage and order new rolls. Paper supply data are displayed in graphical form, giving an overview of the users' behavior. The system uses an ESP8266, the MQTT service, and laser distance sensors. [PERSON] et al. [9] propose a system called the intelligent tissue dispenser system (ITDS) that reduces labor costs to refill a tissue dispenser and increases users' satisfaction. The ITDS consists of three main components, a power source, a microcontroller, and a sensor. The authors describe the infrastructure, the data integration model, the data visualization approach, and an ITDS commercialization model. The authors chose the ESP8266 microcontroller and use an ultrasonic sensor to measure the actual distance of the object from sensor. The US-015 is chosen instead of the HC-SR04 because it can operate at 3.3 V. The reading level status can be set at three levels, i.e., low, medium, and high. The main limitation of all the systems described [3; 4; 8; 9] is that they require replacing the existing infrastructure (paper dispenser) and mounting a completely new set of devices. [PERSON] et al. [10] propose a product-level sensor for a product dispenser. It comprises an ultrasonic-level sensor for determining the level of the sheet product contained in the dispenser. It includes product-level sensors for rectangular tissue boxes and circular dispensers. However, the sensor size is too large for public toilets. The performance of ultrasonic and laser distance sensors is compared in two papers [11; 12]. The first group of authors [11] chose HC-SR04, a popular ultrasonic sensor. The second group [12] chose the VL53 LOX Time-of-Flight (ToF) laser-ranging sensor.