Research On Optical Fiber Monitoring Technology For Straightness Of Scraper Conveyor Under Floor Fluctuation Conditions

Online monitoring of the straightness of the scraper conveyor at the working face,timely transmitting the real-time shape of the scraper conveyor to the control center,and timely adjusting the shape of the scraper conveyor are of great significance for achieving intelligence and guiding the normal production of the working face.In order to meet the current demand,the fiber Bragg grating(FBG)straightness monitoring method for scraper conveyors has emerged as the times require.As a high-precision method for monitoring the straightness of scraper conveyors,when there are fluctuations in the bottom plate of the working face that cause a large slope angle,the strain of the substrate grooved FBG sensor may exceed its long-term allowable strain range.Based on the fiber grating sensing theory,this thesis designs a large strain fiber grating sensor,establishes a scraper conveyor straightness monitoring system,and monitors the straightness of the scraper conveyor under the condition of undulating floor.The main research contents are as follows:(1)The bending principle of the scraper conveyor at the working face is analyzed,and the curvature radius of the scraper conveyor at the undulating section is calculated.It is believed that the excessive strain of the fiber Bragg grating sensor is related to the vertical bending of the scraper conveyor caused by the varying slope angle.The relationship between the wavelength and curvature of the fiber Bragg grating sensor is analyzed,and a model of the sensor and the flexible substrate is established.The curvature of the corresponding position is derived through mathematical methods,The principle of fiber grating straightness monitoring for scraper conveyor is revealed.(2)In response to on-site problems,an analogy method was used to analyze and consider that the sensitivity of fiber gratings can be changed by changing the crosssectional area of the grating segment and the substrate of the fiber segment.Based on this principle,a large strain fiber grating sensor was designed by increasing the crosssectional area of the structural grating segment and reducing the cross-sectional area of the structural fiber segment.(3)The relationship between the strain transfer efficiency of the sensor and the influencing factors such as the elastic modulus and radius of the adhesive layer,as well as the adhesive length of the fiber grating,was calculated and analyzed.The structural dimensions were determined.Through numerical simulation,a numerical model of the large strain fiber grating sensor was established,and appropriate materials were selected based on the simulation results.(4)A large strain fiber Bragg grating sensor experimental platform was built.By controlling variables,the relationship between the strain in the phase of strain increase and strain decrease of the large strain fiber Bragg grating sensor and the wavelength variation of the fiber Bragg grating was measured,and the characteristics of the sensor such as linear error,sensitivity,and hysteresis were obtained.The feasibility of sensor application was analyzed based on field practice.By designing a large strain fiber optic grating sensor,technical support is provided for the monitoring of the straightness of the scraper conveyor under undulating floor conditions,and the problem of the limited long-term allowable strain range of the fiber optic grating sensor is solved.It has application prospects in the field of online monitoring of the straightness of the scraper conveyor.The thesis has 56 figures,4 tables,and 77 references.