ABSTRACT
As we discussed in Chapter 1, the controller is a system driven by the measured signal y and by the reference signal r. It produces the control signal u to be fed into the control object. A linear controller can be represented as
u(t}=Fr(p)r(t)-Fy(p)y(t} (6.1)
with the feedback controller Fy and prefilter Fr. Traditional, analog, controllers are continuous time systems as above, while sampled controllers (see Section 6.7) are discrete time systems (replace p with q). In this chapter we will study the closed loop system, i.e., the system obtained when (6.1) is fed back to the control object. Many of the expressions obtained look like the SISO, continuous time result known from basic control theory.
