| Active Phased-Array Antenna(APAA)is a kind of antenna that can adjust the electrical performance by changing the current phase through the wave-controlled circuit.Due to its strong multi-target tracking ability,resolution,versatility,and anti-jamming ability,APAA is widely used in the military field.However,when the active phased array antenna is faced with a complex service environment such as snow,snow,wind,and impact,the array surface will deform,leading to the change of the position of the antenna unit center,and then lead to the deterioration of the antenna electrical performance.It is necessary to calculate the electrical compensation amount through the reconstructed array deformation,and then adjust the electrical performance accordingly.However,the existing deformation reconstruction methods cannot meet the accuracy requirements in practical engineering due to their defects.At present,the curvature-based deformation surface reconstruction can not effectively calculate the non-unidirectional deformation form.The model accuracy limits the reconstruction accuracy of physical model-based reconstruction methods in engineering practice.To solve these problems,this paper mainly studies the following contents:(1)A sensing system for an active phased array antenna is proposed.Using the WDM technology of fiber Bragg grating sensor,the fiber Bragg grating sensor array is arranged in the antenna array to collect optical signals.Wavelength information is demodulated by the demodulation device and then converted into a strain variable and transmitted to the monitoring center.The deformation of the structure and the corresponding compensation are calculated through the monitoring center and transmitted back to the antenna end.The measurement problem of the fiber Bragg grating sensor is also studied,and the calibration and calibration experiments are carried out for a certain type of fiber Bragg grating sensor.(2)A new triangular element surface reconstruction method based on orthogonal curvature is proposed.First,an orthogonal mesh with trigonometric elements is divided on the surface to be reconstructed,and the measured strain is transformed into the orthogonal curvature.Then the coordinate increment of each grid is obtained by calculating the shape of space curves in different directions.Finally,according to the characteristics of the triangular element,the shape of the whole surface is combined.The proposed method is verified by the deformation of the finite element model of the aluminum plate under six working conditions.The results show that the proposed method is better than the existing method.An array antenna sample is taken as the object,and six kinds of deformation experiments are carried out.The deformation of the antenna element is calculated from the strain measured by the fiber grating sensor.The results show that the proposed method is more practical than the modal method.(3)A deformation reconstruction method with integrated transfer learning is proposed.The simulated strain and displacement calculated based on the physical model method are recorded as source data,and the combination of strain and displacement measured in practice is recorded as target data.Firstly,an affine transformation is used to solve the problem of data dimension inconsistency,and then the least square method is used to obtain the coefficient representing the distance between the source domain and the target domain.The distance coefficient is used to transform the source domain into data that is very similar to the target domain,and the data set and the target data set are composed of a new data set.The weighted enhanced regression algorithm two-stage Tradaboost.R2 is used to adaptively configure the proportion of each group of data in the new data set so that the reconstructed prediction model trained by the new data set is the best.Taking a large UAV wing as the test object,30 groups of target data were tested by FBG sensor and photogrammetric measurement,and 500 groups of deformation results were calculated by the modal method as the source data.The proposed method was used to train and reconstruct the prediction model,and the deformation under random load conditions was calculated.Compared with the measured results,it can be seen that the reconstruction accuracy is greatly improved.(4)An antenna monitoring software is developed based on the Microsoft Foundation Classes(MFC)library in C++ language.The software can obtain the strain collected by the fiber grating sensor,calculate the displacement by using the deformation reconstruction algorithm,then obtain the compensation amount according to the electric compensation theory,and display the deformation status of the model in real-time.Deformation monitoring of a sample of an active phased array antenna was carried out.According to the actual working conditions and reconstruction requirements,a suitable reconstruction method was selected,and a fiber grating sensor was designed and installed.According to the final monitoring results,several problems that should be paid attention to in the actual engineering are discussed,including the selection of reconstruction methods,the design of sensors,and the installation and testing,which are of far-reaching significance to the engineering application of deformation reconstruction. |
