Palautesäätö

Palautesäätö, known in English as feedback control, is a method used to regulate the behavior of a dynamic system by using information about its output to influence its input. The aim is to make the output follow a desired reference trajectory or setpoint, while rejecting disturbances and compensating for model inaccuracies.

Typical elements of a Palautesäätö system include a plant (the system to be controlled), a sensor that measures the output, a controller that computes a corrective input from the error signal (the difference between reference and measured output), and an actuator that applies the control signal to the plant. The path from output back to input constitutes the feedback loop.

Operation relies on the controller processing the error signal to generate a control action. In linear time-invariant systems, common configurations include proportional (P), proportional-integral (PI) and proportional-integral-derivative (PID) controllers. The choice of controller affects stability, speed of response, and robustness.

Design goals emphasize stability (avoiding oscillations or runaway behavior), accuracy (low steady-state error), fast response, and robustness to disturbances and modeling errors. Trade-offs between sensitivity to noise and responsiveness are common, and real-world implementations must consider time delays, nonlinearities, sensor noise, and actuator saturation.

Applications are widespread and include process industries, heating, ventilation and air conditioning, automotive systems (such as cruise control), robotics, power electronics, and consumer electronics for maintaining temperature, speed, position, and other variables.

Overview lists the evolution from classical methods toward advanced techniques like model predictive control and robust control, while the basic principle of feedback remains central to regulating dynamic behavior.