Every activity in our daily lives is affected by some form of control system. The concept of a control system also plays an important role in the working of space vehicles, satellites, guided missiles, etc. Such control systems are now an integral part of modern industrialization, industrial processes, and home appliances. Control systems are found in a number of practical applications like computerized control systems, transportation systems, power systems, temperature limiting systems, robotics, etc.

In this Article, We will be going through different types of Control Systems, In the previous Articles We have gone through what is Open-Loop System and Closed-Loop Systems, In this Article we will Explore Different types of systems such as Natural Control Systems, Man-made systems, Liner system, Non-linear System and Various other types of systems.

What is a Control System?

Control means regulate, control, direct, or command. A control system is thus an arrangement of different parts of the system connected together in such a way as to control, direct or command itself or other systems.

Example : if a switch is used to turn a light on or off, the entire system is called control.

Bulb Control System

Different Types of Control Systems

Different Types of Control Systems are Given Below:

1. Natural control system
2. Man-made control system
3. Automatic control system and Combinational control system
4. Time-variant control system and Time-invariant control system
5. Linear control system and Non-linear control system
6. Continuous-Time control system and Discrete-Time control system
7. Deterministic control system and Stochastic control system
8. Lumped-parameter control system and Distributed-parameter control system
9. Single-input-single-output (SISO) control system and Multi-input-multioutput (MIMO) control system
10. Open-loop and Closed-loop Control System

1. Natural Control System

The biological system inside human being are of natural type.
Example : Temperature of human body, solar system, digestive system and pH value of the blood etc.

2. Man-Made Control System

We are using various types of systems in our daily life which are manufactured and designed by humans are said to be a man-made control systems.
Example : Automobile system, power plant, switches and various controllers etc.

3. Automatic and Combinational Control System

Automatic Control System: These systems are actually made by using mathematics and engineering theories.
Example : sensors, responders etc.

Combinational Control System: These systems are combination of natural and man-made control systems.
Example : Driving a vehicles.

4. Time-variant and Time-invariant Control System

Time-variant Control Systems: Time varying control systems are those in which the parameters of systems are varying with the time. This is not dependent on whether input and output are function of time or not.
Example : space vehicle whose mass decreases with time, as it leaves earth. The mass is parameter of space vehicle system.

Time-Variant Control System

Time-invariant Control Systems: Time invariant control systems are those in which the parameters of systems are not varying with the time. here the inputs and outputs are function of time but parameters of system independent of time.
Example : Inductance, resistance and capacitors etc.

Time-Invariant Control System

5. Linear and Non-linear Control System

Linear Control System: the system said to be linear when the superposition principle is applied to it and satisfies the properties of homogeneity and additivity.

• Homogeneity property: f(x+y) = f(x) + f(y)
• Additive property: f(ax) = a f (x)

Non-Linear control system: This are the control systems which are not satisfies the properties of the homogeneity and additivity.

f(x) = x3

6. Continuous-Time Control System and Discrete-Time control system

Continuous-Time Control System: In the continuous time control system variables are the functions of a continuous time variable ‘t’.
Example : armature type speed control of motor.

Continuous-Time control system

Discrete-Time Control System: In discrete time systems one or more systems variables are known only at certain discrete intervals of time. This is not continuous on time.
Example : Microprocessor or computer based systems use this.

Discrete-Time control system

7. Deterministic and Stochastic Control System

Deterministic Control System: For an input signal or signal interference, the output can be predicted or repeated.

Deterministic Control System

Stochastic Control System: A control whose output cannot be seen or predicted. Any input signa l or interference signal is returned.

Stochastic Control System

8. Lumped-Parameter and Distributed-Parameter Control System

Lumped-parameter Control System: the control system which are describe by ordinary differential equation are called Lumped parameter systems.
Example : networks with different parameters like inductance and resistance etc.

Distributed-parameter Control System: the control system which are describe by partial equation are called Distributed parameter systems.
Example : Transmission lines having parameters resistance and inductance this are totally distributed along with it.

9. Single-input-single-output (SISO) Control System and Multi-input-multioutput (MIMO) Control System

Single-input-single-output (SISO) Control System: The system having only one input and one output are called single input single output systems.

Multi-input-multi-output (MIMO) Control System: The system having multiple type of inputs and multiple output is called multiple input multiple output.

SISO and MIMO System

10. Open-loop and Closed-loop Control System

Here, we are going to learn about all the things regarding Open-loop and Closed-loop Control System :

10.1. Open-loop Control System

The system in which the output is dependent on input but input is totally independent of the output or changes of output system, is called open loop control system.
Example : Traffic signal, washing machine, bread toaster, room heater, fan regulator etc

Open-loop Control System Advantages

• Such systems are easy to design.
• These systems are easy from point of view of maintenance.
• Economical.
• Highly Stable.
• Very convenient when output is difficult to measure.

Open-loop Control System Disadvantages

• These systems are inaccurate and unreliable.
• These systems cannot sense the internal disturbance in the system, after controller stage.

10.2. Closed-loop Control System

This is type of control system in which its control action depends on both input signal as well as output response.
Example : Automatic electric iron, ship stabilization system, Home heating system, missile launcher, speed control of DC motor, etc.

r(t)= reference input, e(t)= error signal, c(t) = controlled output, m(t)=manipulated signal, b(t)=feedback signal.

Closed-loop Control System

Advantages of Closed-loop System

• More accurate than open loop system.
• These systems can change environmental changes as well as internal disturbance.
• There is less effect of nonlinearities and distortions.
• High bandwidth of operation.
• Automation facility available.

Disadvantage of Closed-loop System

• Complicate maintenance.
• Complex design
• Expensive and less stable.

Comparison Between Open-loop and Closed-loop Control Systems