Automatic process control systems are used in various industries to maintain and regulate processes, ensuring they operate efficiently and within specified parameters.
The mainly used two types of automatic control systems in industries are closed-loop or feedback control systems and open-loop or feed-forward control systems, and this post or article shows these control system advantages and characteristics.
Closed Loop or Feedback Control System
In this type of system, the control variable is measured and compared with the reference input. Its difference is the input signal.
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That is, the loop in which the main variable is used to control the process/input is called a closed-loop control system.
It is clear from a fig that the main variable is used to automatically regulate steam input. That is, steam is controlled by the main variable (temperature), so it is a closed-loop control system.
Advantages
Only one controller is used to change the entire input.
Characteristics
1. Minimum derivation, following a disturbance.
2. Feedback control cannot give close control when there is a large time delay in measuring price output as when the main variable is a chemical composition, a molecular weight.
Open Loop or Feed Forward Control System
If the main variable is not used to control any input, it is called an open-loop control system. In this, each piece of information is controlled by a separate controller.
It is clear that the pressure inside the jacket is controlled by the pressure controller and the flow is controlled by the flow controller.Â
It is clear from Fig that the temperature of the kettle which is the primary variable is neither used for pressure control nor liquid flow control nor is it used for temperature control.
The feed-forward control system cannot maintain the C at a set point, So the method is not accurate.
Advantages
1. Simple construction and easy maintenance.Â
2. No stability problem.
Automatic Control Systems Examples
Automatic control systems are widely used in various industries and applications to regulate and manage processes efficiently.Â
1. Thermostat in HVAC Systems
In heating, ventilation, and air conditioning (HVAC) systems, thermostats automatically control the temperature by turning the heating or cooling system on or off based on the desired setpoint.
2. Cruise Control in Vehicles
Cruise control systems automatically maintain a constant vehicle speed set by the driver, making long-distance driving more comfortable and fuel-efficient.
3. Water Level Control in Tanks
Automatic control systems are used to regulate water levels in tanks or reservoirs, ensuring a consistent supply of water for various applications, such as in municipal water distribution systems.
4. Industrial PID Controllers
In manufacturing and industrial processes, PID controllers are employed to regulate variables like temperature, pressure, flow rate, and level to ensure product quality and process efficiency.
5. Elevator Control Systems
Elevators use automatic control systems to move between floors, stop at the desired floor, and open/close doors safely.
6. Traffic Signal Control
Traffic signal systems automatically adjust signal timings based on traffic flow and congestion to optimize traffic management in urban areas.
7. Power Generation and Grid Control
Power plants and electrical grids employ automatic control systems to maintain a stable supply of electricity, regulate voltage, and respond to demand fluctuations.
8. Water Treatment Plants
Automatic control systems are used in water treatment plants to control the addition of chemicals, filtration, and disinfection processes to ensure safe and clean drinking water.
9. Robotics and Automated Manufacturing
Industrial robots and automated manufacturing systems use control systems to perform precise and repetitive tasks, such as welding, assembly, and material handling.
10. Aircraft Flight Control Systems
Aircraft use automatic control systems to stabilize and control their flight, including autopilots that can maintain altitude, heading, and speed.
11. Chemical Process Control
In chemical manufacturing, automatic control systems regulate factors like temperature, pressure, and reactant flow rates to ensure consistent product quality and safety.
12. Environmental Control in Greenhouses
Greenhouse automation systems manage temperature, humidity, and lighting conditions to optimize plant growth and crop yield.
13. Home Automation Systems
Smart homes utilize automatic control systems to control lighting, security, heating, and cooling based on user preferences and sensor inputs.
14. Wastewater Treatment
Automatic control systems play a crucial role in wastewater treatment plants by optimizing the treatment process, managing flow rates, and ensuring environmental compliance.
15. Telecommunications Networks
Telecommunications networks use automatic control systems to manage network traffic, routing, and quality of service to provide reliable communication services.
