A System for Measurement of the Asymmetry between Left and Right Shoulders

The study presents the development of a system for measurement of the asymmetry between the human shoulders. Such measurements are necessary in order to diagnose potential muscular imbalance and when possible, take corrective actions in the form of daily exercises. The system is based on two infrared proximity sensors, installed above the shoulders of the investigated human shoulders. A calibration procedure of the sensors and a following calibration model selection reduced the absolute error for the shoulders difference below 1.49 mm. Yet, if the measurement distance is kept within the range (40...110) mm, the accuracy is below 1 mm. The experiments also showed that the calibration is individual for each reflection surface, which should be considered during experimental measurements.