“…Furthermore, the control plays a very important role in the improvement of production quality, accuracy and in reducing production costs. As a result a great deal of attention has been focused on automatic or self tuning of PID controllers (Astrom & Hagglund, 1995), and in recent decades several kinds of auto-tuning PIDs including self-tuning schemes and adaptive control strategies have been proposed (Chang et al, 2003;Iwai et al, 2006;Kono et al, 2007;Ren et al, 2008;Tamura & Ohmori, 2007;Yamamoto & Shah, 2004;Yu et al, 2007). Unfortunately, most PID auto-tuning methods did not pay sufficient attention to the stability of the resulting PID control system and the tuned PID parameters did not guarantee the stability of the control system after any change of the systems.…”