Onoffreglering

On-off regulation, or onoffreglering in Dutch, is a simple form of feedback control used to maintain a process variable near a desired value by switching the actuator between two states: fully on and fully off. The controller relies on a pair of thresholds to create a hysteresis band around the setpoint, which helps prevent excessive switching.

Operation is straightforward. When the process variable crosses the upper threshold, the actuator is activated; when it crosses the lower threshold, the actuator is deactivated. This bang-bang control causes the variable to oscillate within the hysteresis band around the setpoint. The approach does not aim for precise regulation but for keeping the variable within a acceptable range.

Advantages of on-off regulation include simplicity, low cost, and robustness to parameter variations. It generally requires only basic sensors and a binary actuator. It is well suited for systems where precise control is unnecessary or where actuators switch between two states, such as heating elements, fans, or cooling devices.

Disadvantages include larger fluctuations around the setpoint and potentially higher energy use due to frequent switching. The method can wear actuators over time and may introduce audible or mechanical noise. Sensor noise can trigger unwanted switching unless the hysteresis band is chosen carefully or filtering is applied.

Typical applications are domestic thermostats for heating or cooling, refrigeration, water heaters, and simple automated systems in appliances or light industrial controls where simplicity and reliability are prioritized over precision.