Design and validation of a low-cost wireless pedal force measurement system for biomechanics and rehabilitation applications

The magnitude, direction, and temporal distribution of pedal forces generated by the lower limb are critical parameters in the assessment of athletic performance, motor control, and functional recovery during rehabilitation. However, existing pedal force measurement systems are often limited by their high cost, restricted portability, and dependence on laboratory environments, which constrain their clinical and field applicability. This thesis aims to address these limitations by presenting the design, development, and validation of a low-cost, portable, wireless, and multi-point pedal force measurement system suitable for biomechanics and rehabilitation applications. The proposed system integrates two 50 kg load cells into each pedal, enabling direct measurement of force components at the closest point of application. An ESP32 microcontroller is utilized for data acquisition and wireless transmission, while a custom C#-based software interface is developed to facilitate real-time visualization, recording, and analysis of the collected data. System performance was evaluated through static load tests using calibrated reference weights of 21.1 kg, 42.3 kg, and 63.7 kg, and through positional sensitivity analyses to determine the influence of load application points on measurement accuracy. The findings revealed an exceptionally strong linear relationship (r = 0.9999) between the measured forces and reference loads, indicating high measurement accuracy. The mean difference between pedals was only 0.10 kg, demonstrating excellent repeatability and symmetry. Moreover, a one-way ANOVA result of p = 0.21 indicated that variations in load application position did not significantly affect measurement accuracy, confirming the system's robustness and stability across sensor locations. In conclusion, this study introduces a scientifically validated, cost-effective, portable, and user-friendly pedal force measurement system that integrates low-cost hardware components with wireless communication capabilities. The system offers a reliable and versatile tool for performance monitoring in sports science, symmetry and strength assessments in lower-limb rehabilitation, and advanced biomechanical research. Keywords: Biomechanics, Lower-limb rehabilitation, Pedal force symmetry, Real-time monitoring, Kinetic assessment