Design and Development of an Item Retrieval Detection System for Lockers in the BRAIL Room

Abstract

A locker item retrieval detection system based on the HC-SR04 ultrasonic sensor was developed to automatically monitor locker conditions by distinguishing between occupied and empty states based on distance measurements. The system is integrated with an ESP8266 microcontroller and a DS3231 real time clock (RTC) module to record event timestamps in real time. Experimental testing was conducted using four different sensor placement positions, namely Center Top (CT), Center Back (CB), Left Middle (LM), and Right Middle (RM), with a predefined threshold value used as the classification boundary for locker conditions. The results indicate that the Center Back (CB) position achieved the highest detection accuracy of 92.90%, as its average distance measurement was closest to the threshold value, thereby minimizing relative classification error despite fluctuations caused by ultrasonic reflections within the enclosed locker space. These findings demonstrate that the proximity of sensor readings to the threshold value has a more significant impact on detection accuracy than measurement stability alone.