Design of a Contactless Torque Measurement System Based on the Photoelectric Conversion Principle

Torque can intuitively reflect the working status of mechanical systems, making real-time monitoring and accurate measurement of torque essential for ensuring the safe and stable operation of mechanical devices. By analyzing various existing measurement methods, this article proposes a torque measurement system based on the photoelectric conversion principle. The system uses an LED light source and a four-quadrant detector to capture the minute deformations of the rotating shaft. To mitigate the adverse effects of temperature and current fluctuations on the LED optical power output, a dual closed-loop feedback control circuit for light intensity and current is designed. This system establishes a correspondence between torque measurements and standard values and uses a particle swarm optimization support vector regression (PSO-SVR) algorithm to achieve measurement calibration. Experimental results show that the system has the root mean square error (RMSE) of 0.67, the mean absolute percentage error (MAPE) of 2.4%, and the mean absolute error (MAE) of 0.49, demonstrating good performance in torque measurement.