Examples of open-loop control system and closed-loop control system in daily life

1. Open-loop control system: If there is no feedback loop between the output and the input of the system, the output has no influence on the control effect of the system, and such a system becomes an open-loop control system.

The feed system of the original CNC machine tool is an open-loop control system, and instructions are input into the computer control system to drive the stepping motor to move. The movement of the workbench produces displacement output.

In daily life, many control systems can be understood as open-loop control systems. For example, the rotating speed of an electric fan is determined by the internal gear and cannot be automatically adjusted according to the ambient temperature.

2. Closed-loop control system: feedback control system is also called closed-loop control system. The output has a direct impact on the control effect. Working principle: Closed-loop control has a feedback link. Through the feedback system, the accuracy of the system is improved and the response time is shortened. It is suitable for systems that require high response time and stability.

For example, the controlled object is a furnace, the output variable is the actual furnace temperature, and the input variable is a given constant temperature, which is generally expressed by voltage. The furnace temperature is measured by thermocouple. The thermoelectric potential representing the furnace temperature is compared with a given voltage. The differential voltage between them is used to drive the corresponding actuators for power amplification control.

Extended data:

The input of the open-loop control system directly controls its output. Simple equipment and low cost. It can eliminate many stability problems in closed-loop control system. When the disturbance affects the value of the controlled system to some extent, the control force will change directly with the disturbance. But its anti-interference ability is poor, which greatly limits its control function and its accuracy is lower than that of closed-loop control system.

The feedback control system consists of a controller, a controlled object and a feedback path. The comparison link is used to subtract the input and output and give the deviation signal. In a specific system, this link can be called regulator and controller.

References:

Baidu Encyclopedia-Open-loop Control System

References:

Baidu Encyclopedia-Closed-loop Control System