Table of Contents
What is Control System?
The control system is a system of getting output by regulating, commanding, and directing the input is known as a control system. In our human body, our brain controls our body parts to do specific work. So, in this case, the brain becomes the control system of our body.
As the industry evolved or, we can say, the technology evolved, we all are addicted to the machines, in other words, to the systems. In our daily life, we use washing machines, television, air conditioner, refrigerator, automatic iron, microwave, oven, water heater, etc. To get the output from these devices, we have to control the system and control engineering process to help its design. We have different control systems that control position, velocity, acceleration, temperature, pressure, voltage, current, etc. To be a quality control system, it should have a transparent mathematical relationship between input and output.
Characteristics of Quality Control System
Sensitivity
As the surrounding conditions are consistently changing, the parameters of the control system also change. For a quality control system, it should be less sensitive to an environment, but it should sensitive to input only.
Noise
An undesired input signal is known as noise. The system should be skilled to reduce the noise to get the desired output.
Accuracy
The measurement of error of the system limits the error to as low as possible in normal conditions. The accuracy of the system can increase by giving feedback to the input.
Stability
Stability is a significant characteristic of the control system. If we are getting the same output as we have given to the input, then the system is said to be a stable system.
Bandwidth
The bandwidth of a system should be huge to increase the functioning range. As the frequency range of the system increase, the system becomes efficient.
Speed
The system’s speed is the time consumed by the system to possess an input. The brief time of such systems is less.
Types of Control System
We have two types of control systems.
- Open-loop
- Closed-loop
Open-Loop Control System
In this system, the feedback from the output is not provided to the input of the system. The system is independent of the output.
Examples of Open-Loop Control System
- Manual Electric Iron
These iron starts heating until we switch OFF the iron. It won’t stop heating after it reaches its max capacity. Due to this, we misuse electricity. As we can see, the feedback is not connected to the input. Hence iron doesn’t know when to stop heating.
- Water Heater:
The water heater heats the water until the input voltage is present. It doesn’t care about how much the water is heated. It doesn’t have any feedback to input from the output.
Advantages of Open Loop Control System
- The system is easy to handle.
- Less component & system is economical.
- Less complex and easy to design.
Disadvantages of Open Loop Control System
- Due to the absence of feedback, these systems are inaccurate.
- Produce more errors.
- Unstable.
- More sensitive.
Closed-Loop Control System
It is a modified open-loop control system in which the feedback is connected from output to input to make the system accurate and stable.
Examples of Closed-Loop Control System
- Automatic Electric Iron
In these irons, we can set the maximum heating point. So when the temperature reaches this point, it automatically stops heating and starts getting cool.
- Air Conditioner
When we set the temperature limit in the AC, it cools the room at that temperature. Once the temperature reaches that level, it starts maintaining it by running the system in a controlled way.
Advantages of Closed Loop Control System
- Highly accurate because of feedback.
- Due to getting feedback from the output, the percentage error of the system is small.
- Highly insensitive.
- The bandwidth of the system is more.
- Highly stable.
Disadvantages of Closed-Loop Control System
- Systems are costly due to more components.
- Complex to design and handle.
- Due to the feedback, the gain of the system reduces.
- Require more maintenance.
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