Research On Gear Rotating Fiber Bragg Grating Displacement Sensor

Displacement is one of the most important parameters in the safety monitoring of civil engineering structures. In recent years, safety accidents in civil engineering happened frequently in our country. It is very important to grasp the information timely and accurately, which can understand the civil engineering where the cracks, landslides, relative position changes and so on. It makes the displacement measurement crucial.At present, the displacement measurements were powered by the electric displacement sensor and mechanical displacement sensor. However, the electric displacement sensor has low Anti electromagnetic interference ability, poor waterproofing and other shortcomings; the mechanical displacement sensor has complex installation, low precision and other shortcomings. It is usually fixed the fiber grating at the various of elastic beams in the existing FBG displacement sensor, and the displacement loaded into the elastic beams directly; the deformation of the elastic will cause the wavelength of the fiber grating shifting; then the fiber grating wavelength shift can be measured by the FBG demodulator; finally, the corresponding displacement will be gained through the calculation model. This type of sensor has a lot of advantages, such as high precision, anti electromagnetic interference ability, stability of chemical property, further more, it can be satisfied with the need of the distributed measurement. However, the.sensor also has some disadvantages, such as small range (less than50mm). Therefore, this subject designs a fiber Bragg grating displacement sensor based on this demand. Gear rotary fiber Bragg grating displacement sensor’s range is150mm, and the range can be adjusted according to the actual need measuring range, the linearity of the sensor is1.554%FS, the sensitivity is8.96pm/mm, the hysteresis is4.82%FS. My major works are as follows:1. Designed the mechanical structure of the gear rotary fiber Bragg grating displacement sensor, established the sensor model of the gear rotary fiber Bragg grating displacement sensor.2. Determined the size and materials of the sensor component according to the requirements of the design, and processing to complete all parts of the gear rotary fiber Bragg grating displacement sensor.3. According to the selected materials and size, the gear rotary fiber Bragg grating displacement sensor’s theoretical sensitive can be calculated. The sensitivity in theory is9.93pm/mm, the theoretical resolution is0.101mm.4. Designed positive and negative travel experiment. The experimental results show that the nonlinear error of the sensor is1.554%FS, the sensitivity is8.96pm/mm.