Abstract
In a servomechanism with high accuracy of operation, a feedback loop of high gain is required, whose realization is often difficult according to the parasitic mechanical resonance of actuators.
To avoid this difficulty, a method called “By-Pass Method” giving the construction and equalization of a feedback loop is proposed. In general, an existing actuator has a low pass characteristic, so that if we add a simple by-pass circuit of high-pass type in parallel, a flat frequency characteristic is obtained: in a high frequency region where parasitic resonances exist, the transmission through by-pass circuit is dominant. By this method it is not necessary to equalize one by one the peaks and bottoms in the frequency characteristic of an actuator.
As an example, an application to the tracking servomechanism in video-disk system is shown, and a loop gain over 80db is realized experimentally.
