Analysis of Closed-Loop Control System

A Control System is divided into two categories based on the feedback responses. An Open-Loop Control System is a category of a Control system that works to provide desired output, which does not affect the input of the system. Whereas, a Closed-Loop Control System is another category of Control System, that works along with an analysis sensor, that operates the feedback Responses which influence the system’s operation. Overall, a Control System plays a vital role in emphasizing the fact of automatizing almost every manual action, which is becoming a rapid need of the modern generation.

WHAT IS A CONTROL SYSTEM?

A control system is a device that controls the output of any other connected device. In the modern world, there is a general need for automation of almost everything. A control system is a device that helps in achieving the automation of several devices. They work based on the input provided to the system, according to which they provide the output from the desired device. A control system is categorized into two groups, based on feedback connections.

• Open-Loop Control System

• Closed-Loop Control System

OPEN-LOOP CONTROL SYSTEM:

An Open-Loop Control System is considered as a control system that is not into a loop i.e., the output provided by any device does not influence the input of the control system. In simple words, an Open-Loop Control System is a one-way flow of commands. There is no analysis sensor available in such control systems, due to which there is no feedback from the output. Thus, it is also called a Non-Feedback system.

As the inputs are independent of the output, there are high chances of transition errors to occur and the system is a non-feedback system, it is unable to correct the occurring error.

TYPES OF OPEN-LOOP SYSTEMS:

We are surrounded by the Open-Loop Control System in our everyday life. Some of such devices are:

• Automatic Washing Machine: Almost everyone has done laundry in the washing machine. It is seen that the machine runs a pre-set timing, no matter if the washing is completely done or not.

• Hair Drier: A hair drier is an example of an Open-Loop Control System, as the hair drier will keep running as long as the switch is on irrespective of the hair whether it is dried or not.

• Light Bulb: The light bulb will keep on glowing if the switch is turned on even if it is nighttime or day.

CLOSED-LOOP CONTROL SYSTEM:

A Closed-Loop Control System is a system enclosed in a loop as the name itself suggests. In a Closed-Loop Control System, the output of the device runs a feedback response which influences the input of the system, which in turn makes the system self-reliable to make desired changes. As there is an analysis sensor that provides the feedback, there is a minimal chance of errors, and the system itself corrects several errors. A Closed-Loop Control System is also called an Automatic Control System because the system influences the input according to the provided output.

 TYPES OF CLOSED-LOOP SYSTEMS:

There are several examples of Close-Loop Control Systems that surround us in our day-to-day life. Some of such devices are:

• Air Conditioner: An air conditioner is one of the types of Closed-Loop Control systems. It works based on the temperature of the room i.e., the input of the system is influenced by the temperature of the room (output)

• Electric Iron: Electric iron also works based on the output i.e., the temperature of the iron which prevents the iron from getting overheated.

• Voltage Stabilizer: A voltage Stabilizer is an example of a Closed-Loop Control System that operates based on the voltage (Output) of the system.

ANALYSIS OF CLOSED-LOOP CONTROL SYSTEM:

The working of the Control System is dependent on the feedback from the output. There are two types of feedback

• Positive Feedback:  T=G / 1-GH

• Negative Feedback: T= G / 1+GH

Here, T denotes Transfer Function G denotes Open Loop Gain, and H denotes feedback path gain.

The feedback causes effects on the control system. The sensitivity of a Closed-Loop Control System depends upon (1+GH). The variation in sensitivity due to the negative feedback is expressed as:  S^G_T = ∂T/ ∂G G / T

The effects of the feedback on the noise signal are expressed as:

C(s) / N(s)=Gb / 1+GaGbH

CONCLUSION:

It all comes down to the need of the modern world of making everything automatic and running them to get desired output. This led to the rise of the Control system, which is further divided into two categories based on feedback signals i.e., Open-Loop Control System and Closed-Loop Control System. We are surrounded by these control systems in our day-to-day life, for example, light bulbs, washing machines, air conditioners, etc. There are several advantages of both the Loop Control System, along with a few drawbacks. It is suggested to have detailed knowledge of Laplace Transforms to understand the analysis of the Closed-Loop Control System.