Type of Control System

There are three basic types control system that are:

Feed Forward Control System
Open Loop Control System
Closed Loop or Feedback Controls System

Feed Forward Control System

Feed forward is a type of system which counters the changes in its surroundings.
It is used to maintain the wanted status of the system.
The biggest advantage of this system is that it does not permit the huge disturbance in the output.
The objective of feed forward control, also known as predictive control, is tom measure or predict and potential open-loop disturbances and compensate for them manually before the controlled variable devices too for from the original set point.

Open Loop Control System

Definition: An open-loop control system is one where the control action is independent of the "output" or the desired result. In other words, the system does not use feedback to determine if the desired outcome has been achieved.

Operation: The system takes an input, processes it through a controller, and then drives the actuators to produce an output. The system does not measure or react to the output in any way to adjust the input or control action.

Characteristics:

No Feedback: The system does not have a feedback loop to monitor the output and make adjustments accordingly.
Pre-Set Control Actions: The control actions are predetermined and follow a fixed sequence regardless of the actual output or disturbances.
Simplicity: Open-loop systems are generally simpler and less expensive to design and implement compared to closed-loop systems.

Examples:

Washing Machines: A washing machine that runs for a pre-set time without sensing the cleanliness of the clothes.
Toasters: A toaster that toasts bread for a specific time period without checking the actual level of toasting.
Irrigation Systems: An irrigation system that waters plants based on a timer rather than the moisture level of the soil.

Limitations:

Lack of Accuracy: Since there is no feedback, the system cannot correct any errors or deviations from the desired output.
Susceptibility to Disturbances: Any changes in external conditions or disturbances can affect the performance without the system compensating for them.

Closed Loop or Feedback Control System

Closed loop control system is a control system where its control action depends on both of its input signal and output response.
Closed loop control also known as feedback control system.
Open loop control system can be converted into closed loop control system by providing a feedback. This feedback automatically makes the suitable changes in the output due to external disturbance.
In this way closed control loop control system is called Automatic control system.
Some example of Closed control system are:
- Automatic Electric Iron, Water Level Controller
- An air Conditioner, Missile Launched and auto tracked by Radar.