Design and Development of a Sitting Posture Monitoring System Using Load Cell and Ultrasonic Sensors Based on the ESP32 Microcontroller

Prolonged sitting with poor posture is one of the main causes of lower back pain, especially among office workers and students who spend most of their time at a desk. This study developed a prototype of an ESP32-based sitting posture monitoring chair to monitor sitting position in real time. The system combines an HC-SR04 ultrasonic sensor mounted on the backrest to measure back distance and determine chair status (empty, upright, or slouching), along with four load cells with HX711 modules under the seat to detect user presence. Upright posture is indicated by a green LED, while slouching triggers a red LED and a buzzer. From 4 test trials, the system was able to determine chair status with an accuracy of 85% and an average distance measurement error of 2%. This prototype is expected to serve as a low-cost, simple, and non-invasive alternative for posture monitoring.