Analog control system

The analog control exists when all variables in the system are analog representations signals

as shown in the following figure.

 

In this loop, main components are:

• Process transfer function to be controlled (Some examples are given in chapter 2), Gp

• Analog controller that manipulates the process to carry out the required performance,

  Gc

• Measurement transfer function of transducers, H

An analog controller is a device which implements the controller modes described in this

chapter, using analog signals to represents the loop parameters. The analog signal may be in the form of an electric current or a pneumatic air pressure. The controller accepts a

measurement expressed in terms of one of these signals, calculates an output for the mode being used, and outputs an analog signal of the same type. Sins the controller does solve equations, we think of it as an analog computer. The controller must be able to add, subtract, multiply, integrate, and find derivatives. It does this working with analog voltages or pressures.