Modeling wind-gust disturbances for the analysis of antenna pointing accuracy

This paper develops and compares three wind models used to simulate antenna pointing errors. The first model represents wind forces acting on the antenna dish, thus closely representing actual wind action. The second model represents wind gusts as torque disturbances applied at the antenna drives. The third model represents gusts acting at the antenna rate input. A wind filter introduced in this paper, makes the wind gusts of the third model equivalent to the gusts of the second model. The third model is applicable to the currently developed models of the antenna's closed loop systems. Simulink models of the 34-meter and 70-meter antennas' close-loop system were used to simulate antenna pointing errors in wind gusts. The paper shows that for the NASA 34-meter and for the 70-meter antennas, all three models give similar results, and the results are compatible with field measurements of the servo errors taken in wind.