Relay feedback auto-tuning of cascade controllers

Abstract

It is shown that the relay feedback auto-tuning technique can be extended to auto-tune cascade controllers. The use of the relay allows the tuning of the secondary loop to be done without necessarily placing the primary controller in manual mode. It also turns out that the relative speeds of the loops in cascade can be derived from the limit cycle oscillations obtained from relay feedback auto-tuning.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>