Which two types of control actions are commonly used in control systems?

Open-loop and closed-loop control represent two fundamental types of control actions in control systems, each with distinct characteristics and applications.

Open-loop control refers to systems where the control action is not influenced by the output. In these systems, a predetermined set of inputs is provided, and the control system operates based on these inputs without any feedback. This can be effective for processes where the relationship between input and output is well understood, but it lacks the ability to correct for disturbances or changes in system dynamics.

Closed-loop control, on the other hand, incorporates feedback into the control system. This means that the output is continuously monitored and compared to a desired setpoint. Any deviation from the setpoint generates an error signal, which prompts adjustments to the input to correct the output. This type of control is highly effective in maintaining system performance despite variations in the environment or process parameters and is widely used in various applications where precision and reliability are critical.

The integration of feedback in closed-loop systems allows for greater accuracy and stability compared to open-loop systems, making this distinction essential for understanding the functionality and effectiveness of different control strategies.