2. Frequency synthesis methods

Digital cascade correctors, such as the one shown in figure 3 , will be studied in some detail in this article.

An initial method for determining these correctors will be developed in this section. It is based on the use of frequency methods, which were the basis of correction for continuous linear servo systems. For these systems, it has been possible to define frequency specifications: resonance coefficient, bandwidth, gain margin, phase margin, etc., and to determine the most suitable corrector: phase advance, integral action, PI, PID, etc.

Engineers have acquired a great deal of knowledge in this field of frequency correctors, and it therefore seems interesting and natural to try and transpose this knowledge to the case of digital correctors....