Regulators can be developed using analog and digital techniques.
Different mathematical methods are needed to analyze and design analog
and digital regulators. Though digital technology can replicate analog
system operation, its abilities go much further. For example, nonlinear
and self-adjusting systems, which are difficult to create using only an
analog system, can be designed. The main issue in digital control is
regulator structure and parameter definition.
After the parameters are determined, implementation of controller
algorithms is a simple task.
Regulator systems are widespread in industry applications. In many
cases, the process is passed with a preset temperature profile. These
applications need a corresponding regulator to satisfy process
requirements. The structure of the simplest regulator is presented in
Figure 1. Structure of the Simplest Regulator
This structure presents an automatic control system with feedback. See
the following definitions:
w(t): System function algorithm
u(t): Control effect
z(t): External disturbance impact, which must be minimized
y(t): Output variable
e(t) = w(t) - y(t): Output variable y(t) deviation from required value
Examples of output variables are: temperature in the stove, the engine
shaft rotation speed, liquid level in the cistern,
etc. The key to temperature control is to constantly adjust the output
variable, y(t), so that it is near the value of w(t). Doing this, will
minimize the control error, e(t).
Temperature adjustments can be made with an automatic Regulator, Gr
(Figure 1), which is described by control law:
u(t) = Gr[e(t)].
To select the correct control law, the automatic regulator must know
the mathematical model of the control object:
y(t) = Go[u(t)].
The mathematical model is usually a nonlinear, ordinary system of
differential equations or differential equations in partial
derivatives. Identifying the form and coefficients of these equations
is done via the control object identification task. For conventional
systems, mathematical models are commonly used and then the principal
task is identification of equation coefficients. In many cases, these
coefficients can be selected empirically during the system tuning
process or by performing some special tests.
Some features of control systems with feedback indicators are:
Click here to read the rest of the technical
- Independent corrective action initialization when control
variables deviate from reference values.
- Dynamic regulation of temperature variation with minimal