The Research Of Optimal Sensors Placement Method In Modal Identification Of Cable-net Deployable Antenna

Cable-net deployable antenna has become the mainstream of the development ofspace-borne antenna for a long time in the current and future because of its excellentcharacteristics such as low weight, large-caliber, low cost, good stability, high precision,flexible adjustability and so on. However, it is due to the particularity of the structure ofcable-net deployable antenna that causes many difficulties for the modal identification.A key problem is that how to place the sensors reasonably. Based on a finite elementmodel of the20m cable-net deployable antenna, the method of optimal sensorplacement is investigated in this paper. And a creative algorithm is proposed.Furthermore, the correctness and the feasibility of applying in practical engineering ofthe algorithm are validated in the paper. The main research works are given as follows:Firstly, set up an ANSYS finite element model based on20m cable-net deployableantenna, and do some research on key technologies of modeling. At the same time,make modal calculation of the finite element model.Secondly, consider the characteristics of all kinds of algorithm of optimal placementof the sensor, and find out several algorithms which are suitable and mature to the largespace flexible structure (modal kinetic energy method, effective independence method,accumulating method based on the QR decomposition).Thirdly, in order to improve the effective independence method, a new approach ispresented, which combines the effective independence method and weighted averagedisplacement. This new approach has been applied to finite element model of thecable-net deployable antenna. The index of model assurance criterion (MAC) matrix,FISHER information matrix and singular value which are to be as measures are used toanalyze the optimize results between the new method and the old.Fourthly, the combination method is put forward to according to complementaryadvantages and disadvantages between the improved effective independence methodand the accumulating method based on QR decomposition. The transient responseanalysis module of ANSYS and ME’scope software are used to simulate the modalidentification process, whose results is in contrast to finite element modal calculationresults.Finally, Design and process the reflector frame part of cable-net deployable antennashrinkage10:1to physical model, a series of experiments about the optimal sensorplacement are conducted by the combination method and LMS modal testing system.The results of the experiments can verify well the calculation results of the finiteelement modal.