Parameter Identification And Experimental Of Large Space Structure Based On Photogrammetry

Large space structures exhibit complex dynamic characteristics such as low elastic vibration frequencies and dense modes,which leads to the difference between the parameters determined by simulation calculation or ground test and the actual on-orbit dynamic parameters.On-orbit dynamic parameter identification and subsequent vibration suppression are required to obtain structural vibration response data.Photogramme try technology not only avoids the adverse effects such as additional quality brought by contact measurement,but also can collect rich observation data.Therefore,the use of photogrammetry to identify large space structures dynamics has been studied.Firstly,the binocular stereo vision measurement technology,the camera calibrat io n method and the distortion correction principle were studied.The industrial camera developme nt environment was configured and a 3D reconstruction program was developed.Secondly,the structural vibration measurement algorithm is studied to improve the detection efficiency and measurement accuracy.In terms of measurement efficiency,a fast point-pointing algorithm is designed.The image is segmented based on the pre-selected threshold and then the edge contour is retrieved and filtered.The contours that meet the requirements are fitted to locate the marker points.The experimental results show that the algorithm meets the requirement of structural vibration measurement accuracy,and also meets the efficiency requirement.In terms of measurement accuracy,According to the spatial continuity feature of structural deformation,a method for improving the measurement accuracy of the overall deformation of the structure is proposed.Firstly,the profile is divided into different regions according to the structural profile feature and the marker point distribut io n.Then,the coordinate information of the marker points in different regions is used to fit the deformation displacement of the corresponding marker point by using a polynomial.Then,the problem of dynamic characteristic parameter identification is studied.The eigensystem realization algorithm and its extension algorithm are introduced in detail.The natural excitation technology and eigensystem realization algorithm are combined to deal with the identification research under different excitation conditions.Finally,an experimental platform was built.The dynamic parameters of a flexib le aluminum plate were identified under the conditions of unit pulse excitation and environme nt a l excitation.The identification results were consistent with the results of laser displaceme nt sensor measurement and finite element calculation.This proves the feasibility and superiorit y of the large space structures dynamics parameter identification based on photogramme tr y technology.