Command Preprocessor for the Beam-Waveguide Antennas

The high-gain linear quadratic Gaussian (LQG) controllers, designed for 32-GHz (Ka-band) monopulse tracking, have small tracking errors and are resistant to wind disturbances. However, during antenna slewing, they induce limit cycling caused by the violation of the antenna rate and acceleration limits. This problem can be avoided by the introduction of a command that does not exceed the limits. The command preprocessor presented in this article generates a command that is equal to the original command if the latter does not exceed the limits and varies with the maximal (or minimal) allowable rate and acceleration if the limits are met or exceeded. It is comparatively simple since it requires only knowledge of the command at the current and the previous time instants, while other known preprocessors require knowledge of the terminal state and the acquisition time. Thus, the presented preprocessor is more suitable for implementation into the antenna control software. In this article, analysis of the preprocessor is presented. Also, the performances of the preprocessor itself and of the antenna with the preprocessor are illustrated with typical antenna commands.