Control System | open loop system | closed loop system

Control System:-

 A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large industrial control systems which are used for controlling processes or machines.

Types of Control System:-

1. Open Loop Control System.

2. Closed Loop Control System.

1. Open Loop Control System:-

 In an open-loop control system, the control action from the controller is independent of the process variable. An example of this is a central heating boiler controlled only by a timer. The control action is the switching on or off of the boiler. The process variable is the building temperature. This controller operates the heating system for a constant time regardless of the temperature of the building.

 Another example of a control system is a light bulb in our house. When we switch on the switch of the bulb then it gets glow and when we switch off the switch of the bulb then it gets off.

2. Closed Loop Transfer Function:-

 In a closed-loop control system, the control action from the controller is dependent on the desired and actual process variable. In the case of the boiler analogy, this would utilise a thermostat to monitor the building temperature, and feed back a signal to ensure the controller output maintains the building temperature close to that set on the thermostat.

 A closed loop controller has a feedback loop which ensures the controller exerts a control action to control a process variable at the same value as the setpoint. For this reason, closed-loop controllers are also called feedback controllers.

 Another example of closed loop control system is Smart air conditioner. When you set the temperature as you want (for example 22°C) and when room temperature reaches your desired temperature (i.e. 22°C) the Smart Air conditioner will get off automatically.