Authors: M. Pavani, K. Shreya, Kb. Chetana Reddy, M. Deepika, M. Ranjith Kumar
Abstract: – Manual repetition counting during strength training is prone to human error, and conventional motion-based rep counters cannot verify whether a user has actually completed the required Range of Motion (ROM) for an exercise. This often results in the counting of partial or incomplete repetitions, damaging the reliability of workout data. This paper proposes a Universal Rep Counter with ROM Detection, an embedded system built around an MPU6050 inertial measurement unit (IMU) and an ESP32 microcontroller. The system fuses accelerometer and gyroscope data using a complementary filter to estimate the joint or limb angle in real time, and validates each repetition against a configurable minimum-maximum ROM threshold using a finite-state counting algorithm. Only movements that traverse the full required range and return to the starting position are registered as valid repetitions. The design incorporates an OLED/LCD display for real-time feedback and push-button controls for exercise selection, calibration, and reset, making the system adaptable to a wide range of resistance exercises including bicep curls, squats, bench presses, shoulder presses, rows, and lat pull-downs. This paper presents the system architecture, sensor-fusion methodology, rep-validation algorithm, and expected behavior based on simulated sensor data, and outlines a roadmap for hardware validation and future extensions such as automatic exercise recognition and AI-based form analysis.
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