Precise Alignment of Spacecraft Antenna using Theodolite based Hardware and Software Interface

摘要

The antennae for spacecraft, ground stations, military ships, LOS links, aircraft etc., require precise alignment with their reference axes for the best electrical performance. Theodolite based, noncontact, 3-D measurements are used for alignment, which involves coordinate determination of targets and their transformation into different axes systems. This paper presents the development of a computer based system for the above. The interface for electronic theodolites, the mathematical model and software for co-ordinate determination and transformation have been developed. Triangulation Principle has been used to establish the theodolite co-ordinate system. The co-ordinate transformation involves formulation of an over determined set of nonlinear equations and their solution using singular value decomposition. Validation of the system along with a discussion on repeatability and accuracy of measurement are presented. With an additional module for relating reference cube axes with theodolite axes, the system has been successfully used for alignment of steerable antenna of GSAT-1.