Relay Feedback Autotuning Technique

The Relay Feedback autotuning technique, which is used by the Relay Feedback instance of the PID Online Autotuning VI, uses an on-off relay in a feedback loop to determine ultimate gain and ultimate frequency. This technique is a variation on a closed-loop (ultimate gain) test, but is more efficient for systems with a large time constant. This method also incorporates hysteresis to avoid noise in the system.