regleringsglidning

Regleringsglidning is a term used in control engineering to describe a gradual drift or creeping of a regulator’s performance, which causes the controlled variable to deviate from the intended setpoint over time. It can appear as a slow, persistent offset or as a slowly changing regulation level, even when the setpoint is constant and nominally stable.

Causes of regleringsglidning include persistent disturbances (such as load changes or environmental shifts), mismatch between the process model and the real plant, and nonlinearities or hysteresis in sensors and actuators. Time delays, sensor bias or drift, and actuator saturation can also contribute. In systems with integral action, windup due to saturation or limited actuator range can lead to temporary drift after disturbances. Measurement noise and aging components may gradually erode regulation accuracy.

Consequences of regleringsglidning are reduced regulation precision, increased energy use or wear due to unnecessary actuator activity, and in some cases instability or oscillations if the drift interacts with the loop dynamics.

Diagnosis typically involves analyzing the regulation error over time, step or disturbance-response tests, and checking for biases in measurements or consistent deviations under steady disturbances. More advanced methods include disturbance observers, filter design, and model validation to identify sources of drift.

Mitigation strategies focus on improving robustness and accuracy, such as anti-windup schemes, calibration and bias compensation, adaptive or robust control techniques, model predictive control, and the inclusion of feedforward paths or disturbance rejection mechanisms. Regular maintenance helps prevent drift due to aging components.