Dynamic Compensation Technique for POF Curvature Sensors

Polymer optical fibers (POF) can be applied as curvature sensors due to its high strain limits, fracture toughness, and flexibility in bend. However, POFs present viscoelastic behavior, which leads to a phase lag between the stress and strain. The polymer viscoelasticity can be associated to the high hysteresis and the errors that curvature sensors based on POF may present. For this reason, this paper proposes a dynamic compensation technique based on the angular velocity of the sensor. The technique comprises of initial quasi-static tests and tests with different angular velocities for the reduction of the sensor root mean squared error (RMSE) and hysteresis. Results show a reduction of both hysteresis and RMSE in almost all angular velocities tested. The mean reduction of the hysteresis is 20%. Whereas a mean reduction of about 3 times of the RMSE was obtained. Furthermore, the compensation technique results on a calibration equation, which can be applied in real-time measurements.