Design and development of a compact portable assisted ergometer for upper extremity rehabilitation

Abstract

This paper presents an assisted ergometer system for upper extremity rehabilitation. The system integrates a servomotor-driven ergometer mechanism with an embedded control unit wirelessly interfaced with a heart rate monitoring sensor. It consists of a main frame (fitted with pedals and a servomotor), a microcontroller, and a heart rate sensor. The main frame houses pedals connected to the motor through a bevel gear mechanism that efficiently transfers power from the motor shaft to the horizontal pedal shaft, enabling smooth and consistent motion. The central embedded control unit receives real-time heart rate data from the sensor via wireless communication. The servomotor speed is dynamically adjusted based on the subject's heart rate by maintaining the heart rate within 50-80% of the age-predicted maximum. This ensures an appropriate level of exertion during the exercise session. A Proportional-Integral-Derivative (PID) control algorithm is implemented to provide precise feedback regulation, facilitating accurate and responsive motor speed adjustments tailored to the subject's physiological responses. The paper comprehensively describes the ergometer system's design and implementation, detailing the integration of hardware components and the algorithms employed for heart rate monitoring and motor control. Overall, the proposed system offers a practical and innovative solution for upper extremity rehabilitation by leveraging modern embedded technology, mechanical design considerations, and established exercise prescription guidelines. © 2025 Author(s).