Gain tuning is the process of selecting the proportional, integral and derivative gain values of a feedback control loop so that the controlled system responds with the desired speed, stability and overshoot characteristics. Gains are set through analytical methods such as Ziegler-Nichols, model-based optimisation, or empirical trial-and-error adjustment on the physical system. Poorly tuned gains can cause sluggish response, excessive overshoot or instability, making gain tuning a critical step in commissioning any PID-controlled actuator, including derivative-only stages of the loop.