Autoguider servo design and testing of the W. M. Keck Telescope

The servo design and model of the W. M. Keck telescopes autoguider is presented. Telescope servo models often do not include the guider loop and therefore do not take advantage of traditional control analysis and test techniques to improve performance. Guide camera dynamics, computational and transport lags, and compensation networks are discussed. A means of measuring the actual frequency response characteristics of the guide loop is presented and the results are compared to those predicted by the model. Guide performance as a function of integration time is illustrated. An improved compensation network is developed and its performance examined.