The Study On Tilt Angle Sensor With High Resolution Dynamic Measurement

Optical fiber sensor has the advantages of high resolution,anti-electromagnetic interference and high sensitivity.At present,the research of fiber optic tilt sensor is main based on Bragg grating(FBG)principle.The continuous monitoring of large building health,such as bridge,tunnel and dam,needs the high-resolution dynamic tilt sensor.Fiber optic tilt sensor can meet the needs of large building health testing,but there is no optical fiber tilt sensor which can be measured in real-time.In this paper,a fiber optic tilt sensor based on fabry-perot interferometer is proposed,which can realize high resolution dynamic real-time measurement of tilt Angle.Tilt sensor uses solid mechanics model,that is made up of inertial mass and double vertical cantilever beam.The magnetic damping structure reduce the vibration influence,which is made of an inertial mass block below with a copper ring and permanent magnets.According to theoretical analysis,the F-P cavity length variation approximates the vertical cantilever deflection corresponding to the inclination angle.Using high speed spectrometer and white light interference rapid demodulation algorithm(WLI),the dynamic real-time measurement of the dip Angle is realized by the dynamic real-time measurement of the absolute length of the f-p cavity.A moving average method is used to extract DC and AC components from the measurement results of the F-P cavity length,the DC and AC signals respectively represent the external inclination and vibration.In order to estimate the variation range of the F-P cavity length and determine the structural parameters of the vertical cantilever beam,the FEA of the designed vertical cantilever structure is conducted.An experiment is carried out by using an adjustable micro-tilt platform mounted on a vibration table.The experimental results show a high inclination resolution of 0.027?and the sensitivity of 304.457um/ ° within the measurement range of ± 1 °.The dynamic resolution of the inclination measurement in ambient vibration is also estimated to 0.63? with the simulated vibration frequency and amplitude of 50 Hz and 20.9 um.Due to the dynamic measurement method,the inclination angle readouts is tolerant of ambient vibration.The tilt sensor also provides information on environmental vibrations,such as frequency phase and amplitude,while the dip is measured.