Control system

A control system is a systematic (strictly defined) set of tools for collecting information about the object under control and the means of influencing its behavior, designed to achieve certain goals. The object of the control system can be both technical objects and people. The object of the control system may consist of other objects that may have a permanent structure of relationships.

Management systems with the participation of people as objects of management are often called management systems , that is, automated management.

Technical control structure - a device or a set of devices for manipulating the behavior of other devices or systems .

The control object can be any dynamic system or its model . The state of an object is characterized by some quantitative values that vary in time, that is , state variables . In natural processes, the role of such variables can be the temperature , the density of a certain substance in the body , the course of securities , etc. For technical objects, these are mechanical displacements (angular or linear) and their speed, electrical variables, temperatures, etc. Analysis and the synthesis of control systems is carried out by methods of a special section of mathematics - control theory .

Management structures are divided into two large classes:

Automated control system (ACS) - with human participation in the control loop;
Automatic control system (ACS) - without human participation in the control loop.

Content

Types of automatic control systems

The automatic control system, as a rule, consists of two main elements - the control object and the control device.

By Management Purpose

The control object is a change in the state of the object in accordance with a given control law. Such a change occurs as a result of external factors, for example, as a result of controlling or disturbing influences.

Automatic control systems

Automatic stabilization systems . The output value is maintained at a constant level (the specified value is a constant ). Deviations occur due to disturbances and when turned on.
Software regulation systems . The set value is changed according to a predetermined program law f. Along with errors encountered in automatic control systems, errors from the inertia of the regulator also occur here.
Tracking systems . The input impact is unknown. It is determined only during the operation of the system. Errors very strongly depend on the type of the function f (t).

Extreme regulatory systems

Able to maintain an extreme value of a certain criterion (for example, minimum or maximum), which characterizes the quality of functioning of a given object. The quality criterion, which is usually called the objective function , an indicator of extremum or an extremal characteristic , can be either directly measured physical quantity (for example, temperature , current , voltage , humidity , pressure ), or efficiency , productivity , etc.

Allocate:

Systems with extreme relay control. A universal extreme controller should be a highly scalable device that can perform a large number of calculations in accordance with various methods.
- The signal controller is used as an analog quality analyzer, which uniquely characterizes only one adjustable parameter of the systems. It consists of two devices connected in series: a Signum relay ( D-flip-flop ) and an executive motor ( integrator ).
- Extreme systems with a non-spinning object
- Extreme systems with inertial object
- Extreme systems with floating characteristic. It is used when the extremum changes in unpredictable or difficult identifiable manner.
Systems with a synchronous detector (extreme continuous systems). There is a differentiating link in the direct channel, which does not let the constant component through. For any reason, this link may not be removed or bridged. This link is impossible or inapplicable. To ensure system operability, the modulation of the driver and the signal coding in the forward channel are used, and a synchronous phase detector is established after the differentiating link.

Adaptive automatic control systems

They serve to ensure the desired quality of the process with a wide range of changes in the characteristics of control objects and disturbances.

By type of information in the control device

Closed ACS

In closed automatic control systems, the control action is formed in direct dependence on the controlled variable. The coupling of the output of the system to its input is called feedback . The feedback signal is subtracted from the driver. This feedback is called negative .

Open ACS

The essence of the principle of open control is a rigidly defined control program. That is, the control is carried out "blindly," without control of the result, based only on the model of a controlled object embedded in the ACS. Examples of such systems are: timer , traffic light control unit, automatic lawn irrigation system, automatic washing machine, etc.

In turn, distinguish:

Open on setting effect
Open perturbing

Characteristics of ACS

Depending on the description of variables, the systems are divided into linear and non-linear . Linear systems include systems of description elements, which are given by linear algebraic or differential equations .

If all parameters of the equation of motion of the system do not change with time, then such a system is called stationary . If at least one parameter of the equation of motion of a system changes in time , then the system is called nonstationary or with variable parameters .

Systems in which external (master) actions are defined and described by continuous or discrete functions in time belong to the class of deterministic systems.

Systems in which random signal or parametric effects take place and are described by stochastic differential or difference equations belong to the class of stochastic systems.

If the system has at least one element, the description of which is given by the partial differential equation, then the system belongs to the class of systems with distributed variables .

Systems in which the continuous dynamics generated at each moment of time is interleaved with discrete commands sent from the outside are called hybrid systems .

Examples of automatic control systems

Depending on the nature of the controlled objects , biological, ecological, economic and technical management systems can be distinguished. Examples of technical management include:

Discrete action systems or automata ( trading , game , music ).
Systems of stabilization of voltage , temperature, fluid level, speed, sound level , image or magnetic recording , etc. These can be controlled aircraft complexes, which include automatic engine control systems, steering mechanisms , autopilots and navigation systems .

Literature

Yashkin II. The course of the theory of automatic control. M., Science, 1986
Polyak B. T., Scherbakov P. S. Robust stability and control. M., Science, 2002
Besekersky V. A., Popov E. P. The Theory of Automatic Control Systems. M., Science, 1966
Tsypkin Ya. Z. Fundamentals of the Theory of Automatic Systems. M., Science, 1977
Novikov DA Theory of Organizational Systems Management . 2nd ed. - M .: Fizmatlit, 2007.
Krasovsky A. A. Dynamics of continuous self-adjusting systems. M. 1963
Morosanov I.S. Relay extreme systems. M., Science, 1964
Kuntsevich V.M. Pulse self-adjusting and extreme automatic control systems. Science, 1966
Rastrigin L. A. Extreme control systems. M., Science, 1974
Butko G. I., Ivnitsky V.A., Poryvkin Yu.P. Performance evaluation of aircraft control systems. M., Mechanical Engineering, 1983