Satellite antenna deformation reconstruction technology based on FBG sensors
Objective In the current era of rapid digitalization,communication satellites play an extremely crucial role.When satellites are in orbit,the antenna is subject to temperature and external mechanical forces,resulting in thermal and mechanical deformations.These deformations cause distortions in the beam direction,significantly impacting the quality and reliability of information transmission.Therefore,reconstructing the deformation of satellite antennas and promptly correcting the phase of the output signals is crucial to ensure the performance of satellite communication.Fiber Bragg Grating(FBG)sensors have made significant progress in structural deformation reconstruction due to their sensitivity to deformation,small size,capability for multi-point measurements through serial connections,and immunity to electromagnetic interference.As the installation process can influence the sensing performance of FBG sensors,the author has developed FBG strain sensors and temperature sensors and designed an FBG deformation reconstruction system suitable for deformation measurements in variable temperature environments.Methods To achieve deformation reconstruction of satellite antennas using FBG sensors,we prepared FBG sensors using polyimide fiber gratings and conducted deformation reconstruction experiments on metal thin plates.Firstly,we analyzed the deformation field reconstruction algorithm based on discrete strain information on the structure surface.Subsequently,with the aid of a self-developed packaging device(Fig.4),we encapsulated the polyimide fiber Bragg gratings with non-metallic packaging materials,thereby preparing fiber Bragg grating strain sensors(Fig.2)and fiber Bragg grating temperature sensors(Fig.3)for deformation reconstruction.The layout of FBG sensors was analyzed using wavelength division multiplexing technology(Fig.6).FBG sensors were calibrated using equally strong cantilever beams and high-low temperature chambers(Fig.11).A three-dimensional deformation reconstruction test platform for simulating satellite antennas in variable temperature environments was built using the calibrated FBG sensors(Fig.7-8),and deformation reconstruction experiments were conducted under different temperatures and loads.To objectively evaluate the accuracy of sensor deformation reconstruction,the measurement values of a laser rangefinder were used as evaluation criteria to analyze the reconstruction accuracy of FBG sensors.Results and Discussions A non-metallic substrate-based FBG strain sensor and an FBG temperature sensor encapsulated in alumina ceramic were designed.A temperature-variable environment fiber Bragg grating(FBG)structural reconstruction system was established using these sensors,along with a grating demodulator and other equipment.The performance of different sensors demonstrated consistency and close sensitivity.The sensors are easy to install and suitable for engineering structural deformation monitoring applications.Conclusions The study describes the performance of FBG strain sensors packaged in flexible non-metallic substrates,exhibiting excellent consistency.The strain sensitivity and thermal response sensitivity of different FBG strain sensors are close.Calibration of the sensors reveals an average strain sensitivity of 0.835 pm/με,with a maximum deviation of 0.014 pm/με among different sensors at different stages.Calculating strain values from the FBG central wavelength and comparing them with strain values from a resistance strain gauge yields an average relative measurement error of 1.98％and a repeatability error of 0.52％.The average temperature sensitivity of FBG temperature sensors is 11.30 pm/℃,with a maximum temperature sensitivity deviation of 0.11 pm/℃ among different sensors.Comparison between measured values of FBG temperature sensors and actual temperatures from a temperature chamber shows an average relative measurement error of 0.94％and a repeatability error of 0.54％.Utilizing the fabricated FBG sensors for strain reconstruction of aluminum alloy specimens and comparing them with a laser rangefinder,the reconstruction error of FBG does not exceed 5.94％at room temperature and 6.97％in a variable temperature environment.
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