COMPARISON OF ONLINE CONTROLLER TUNING METHODS FOR UNSTABLE SYSTEMS

Methods of closed loop identification of a delay plus unstable first o rder model for controller tuning are proposed by the extension of the methods of Jutan and Rodrigues [1], Lee [2] and Chen [3], which are or iginally suggested for stable systems. Based on the identified model, PI controllers are designed and the performance of the closed loop sys tem is compared with all three methods and with the extension of the Y uwana and Seborg method [4]. Two simulated systems are considered: an unstable first order plus delay system and an unstable second order pl us delay system. The extension of the Chen [3] method gives the lowest ISE value among the four methods.