Intelligent Knife Switch Contact Status Monitoring Based on Special-Shaped Beam Fiber Bragg Grating Electromechanical Sensor

Abstract

To ensure the safety of people’s lives and property, the accurate measurement of various small vibrations is of great significance. Using gratings as sensitive components to make optical fiber sensors is a kind of electromechanical vibration measurement device with rapid development. In this study, a special-shaped beam Fiber Bragg Grating (FBG) electromechanical vibration sensor with sensitized grooves is proposed based on equal-strength cantilever beams. The composition and implementation principle of FBG sensing system are expounded, and how to realize the signal induction of FBG under vibration conditions is further analyzed. According to the intrinsic relationship between sensitivity coefficient and natural frequency in vibration sensor, the sensor head structure composed of structural parameters, such as equal-strength beam length of 73 mm, bottom width of 14 mm, and thickness of 5 mm, is finally selected. With the help of ANSYS software to calculate the natural frequency of the sensing head as a theoretical reference value, and SS304 stainless steel is selected as the cantilever beam to obtain a good vibration sensing effect. In the test, the acceleration is set to 0.35 G, and the pulse generates a sinusoidal signal of 0–10000 Hz. The natural frequency of the sensing head is 182 Hz, and the sensitivity is 100 mV/G, which is only small error with the theoretical analysis value calculated by ANSYS. The acceleration of the sensing head is changed, and different degrees of vibration are generated. The results show that the change of output center wavelength has a linear relationship with the acceleration change. The introduction of sensitized grooved special-shaped beams helps to improve the sensitivity of the device to perceive vibration. It is used for the monitoring of the contact status of the intelligent knife switch. The results show that the designed photoelectric grating electromechanical sensor measurement has good repeatability, and the wavelength of the reflection interrogator will suddenly increase and decrease rapidly with obvious regularity.