Open-loop control

How it is used

Used to describe simple systems such as a timer-controlled pump, a conveyor running at a fixed frequency or a stepper motor without an encoder. Engineers choose it when it is cheap and good enough, and say that a system 'runs open loop'.

Example sentences

1. The dosing pump uses open-loop control, so if the hose gets blocked, nobody notices.

2. Open-loop control was fine until the load on the conveyor started to vary.

Common collocations

• open-loop system
• run open loop
• open-loop stepper drive
• open-loop speed control

Related terms

• closed-loop controlControl in which the actual output is measured and fed back, so the controller keeps correcting its command until the output matches the target.
• feedbackInformation about the actual output of a system, such as the measured position or speed, that is sent back to the controller so it can correct any difference from the target.
• stepper motorAn electric motor that turns in small fixed steps, often 1.8° each, so it can be positioned by counting pulses, usually without a position sensor.
• controllerThe device or program that makes control decisions: it reads measurements, compares them with what is wanted and sends commands to motors or other actuators.

More terms: Control Systems

• setpoint
• PID control
• process variable
• tune
• overshoot