Determination of periodic modes in relay servo-mechanisms employing sampled data

A difference equation approach is presented to determine the periodic modes in relay servomechanisms employing sampled data. In using the method, together with Izawa and Weaver´s method, the investigator can have all the information concerning possible periodic modes of a system. This new technique is based on expressing periodic sequences in terms of orthogonal functions in the discrete sense and balancing the harmonics.