Technical Report:7890-TR-1 THE ANALYSIS AND DESIGN OF DIGITALLY-CONTROLLED INSTRUMENT SERVOS

摘要

This report analyzes the effects of time-sampling and amplitude quantization of output and error signals on the performance of a second-order instrument servo which is to be controlled by a digital computer. Two configurations are considered. One is a high-performance type, capable of reproducing sine-wave inputs with a low-frequency phase-shift equivalent to a delay of one-half sampling period and a resonance peak of 2 at a frequency of one-fourth the ampling frequency. The second configuration employs a logarithmic level-selection scheme for the computer output signal. This considerably reduces the number of discrete levels in the decoding of the computer signal required to achieve a given resolution and maximum output shaft rate. Application of the design techniques is made to an instrument servo which converts the signals generated in a digital operational flight trainer to the analog pointer positions of the cockpit instruments.