Research on static shape estimation of truss antennas

The improved high precision and high performance are required to antenna structures. However, this kind of structures tends to deform easily as their size is enlarged. Therefore, in order to keep the surface accuracy of antenna, it is important to estimate a surface configuration of antenna from limited information provided by embedded sensors in structural elements. This paper shows a fundamental examination about the static shape estimation of truss antennas. Two approaches of shape estimation are proposed to deal with the case where measurement points are limited to the distortion in a subset of truss elements. In the first approach, based on the static modal analysis, the modal expansion method, in which the surface deformation of antenna is expressed by summation of natural modal displacements is employed. In the second one, the polynomial approximation method is used based on the assumption that the temperature distribution acting on the antenna can be approximated by a low order polynomial. In this method, to minimize the shape estimation error, the sensor placement can be determined by the optimal location technique including the singular value decomposition. Some numerical examples for the shape estimation of large truss antenna using the proposed estimation methods are illustrated in this paper. From the results of examples, the validity of the present approaches is verified.