4 Examples of Open and Closed Control Systems

Sources

Farhan Sheikh, EEEProject, “Open Loop System [Explained] in Detail” - 2017-09-18, archived on 2024-09-13
El Pro Cus, “What is an Open Loop Control System & Its Working” - Accessed 2024-09-13
Vivien Beverley Fletcher, “Systems Approach Universal System” - 2015
D. Hoyt, Y. Adonyi, S. Kim, Welding Journal, “Microwave Joining — Part 1 : Closed Loop Controlled Microwave Soldering of Lead Telluride to Copper” - 2016
Electronics Coach, “Examples of Closed-Loop Control System” - Accessed on 2024-09-13
Ravi Teja, ElectronicsHub, “Closed Loop System: How It Works & Examples” - 2024-06-21
Electronics Tutorials, “Closed-loop Systems” - Accessed on 09-13-2024

Basic Parts

Reference input: an external signal applied to the summing point
Summing point: sum of all inputs
Control elements: controls the process by sending a control signal
Plant: the system controlled by the feedback control system
Controlled output: output of the plant
Feedback elements:

Open Loop Systems

1. Clothes Dryer

It does not depend on the output and will stop based on the timer.

Function	Component
Reference Input ( $r$ )	Timer
Control Elements ( $g_{1}$ )	Controller
Plant ( $g_{2}$ )	Heating element
Controlled Output ( $c$ )	Clothes Dryness

2. Traffic light

Function	Component
Reference Input ( $r$ )	Internal Timer
Control Elements ( $g_{1}$ )	Controller
Plant ( $g_{2}$ )	Traffic Lights
Controlled Output ( $c$ )	Traffic Signal Output

3. Flashlights

Function	Component
Reference Input ( $r$ )	Light Switch
Control Elements ( $g_{1}$ )	Controller
Plant ( $g_{2}$ )	Bulb
Controlled Output ( $c$ )	Light

4. Water Faucet

Function	Component
Reference Input ( $r$ )	Tap Handle
Control Elements ( $g_{1}$ )	Valve
Plant ( $g_{2}$ )	Water Level
Controlled Output ( $c$ )	Flood

Closed Loop Systems

1. Microwave

Function	Component
Reference Input ( $r$ )	Temperature and Time Selector
Control Elements ( $g_{1}$ )	Controller
Plant ( $g_{2}$ )	- Motor - Fan - Heater
Controlled Output ( $c$ )	Heat
Feedback Elements ( $h$ )	Thermostat

2. Temperature Control System

Function	Component
Reference Input ( $r$ )	Temperature Selector
Control Elements ( $g_{1}$ )	Valve
Plant ( $g_{2}$ )	Tank
Controlled Output ( $c$ )	Achieved Temperature
Feedback Elements ( $h$ )	Pressure Thermometer

3. Current Limit Control

Function	Component
Reference Input ( $r$ )	Current
Control Elements ( $g_{1}$ )	Controller
Plant ( $g_{2}$ )	- Converter - Motor
Controlled Output ( $c$ )	Load
Feedback Elements ( $h$ )	Current Sensor

4. Motor Controller

Function	Component
Reference Input ( $r$ )	Desired Speed
Control Elements ( $g_{1}$ )	- Gain - Op-Amp
Plant ( $g_{2}$ )	- DC Motor - Rotating Shaft
Controlled Output ( $c$ )	Actual Speed
Feedback Elements ( $h$ )	Tachometer