What is a Control System?

What is a  Control System?

Control System Definition

A control system is defined as a system of devices that manages, commands, directs, or regulates the behavior of other devices or systems to achieve a desired result. A control system achieves this through control loops, which are a process designed to maintain a process variable at a desired set point.

Components of the control system

• Controller

• Controlled object

• Executive mechanism

• Transmitter

Features of a Control System

Explicit mathematical relationships

Control system requirements   

• Accuracy

• Sensitiveness

• Low noise

• Large bandwidth

• High speed

• Low oscillation

Type of control system

Open-loop control system : A control system in which the control actions are completely independent of the system output

Advantages of Open Loop Control Systems

• Simple in construction and design.

• Economical.

• Easy to maintain.

• Generally stable.

• Convenient to use as output is difficult to measure.

Disadvantages of Open Loop Control System

• They are inaccurate.

• They are unreliable.

• Any change in output cannot be corrected automatically.

Practical Examples of Open Loop Control Systems

• Electric Hand Drier

• Automatic Washing Machine

• Bread Toaster

• Light Switch

Closed-loop control system: In a control system, the output influences the input so that the input adjusts itself according to the output produced

Advantages of Closed Loop Control System

• Closed loop control systems are more accurate even in the presence of non-linearity.

• Highly accurate as any error arising is corrected due to the presence of a feedback signal.

• The bandwidth range is large.

• Facilitates automation.

• The sensitivity of the system may be made small to make the system more stable.

• This system is less affected by noise.

Disadvantages of Closed Loop Control System

• They are costlier.

• They are complicated to design.

• Required more maintenance.

• Feedback leads to an oscillatory response.

• Overall gain is reduced due to the presence of feedback.

• Stability is the major problem and more care is needed to design a stable closed loop system.

Practical Examples of Closed Loop Control System

• Automatic Electric Iron

• Servo Voltage Stabilizer

• Water Level Controller

• Cooling System in Car