“…It has been suggested, for example, that just 5 to 10% of control loops cannot be controlled by SISO PI or PID controllers (Koivo and Tanttu, 1991); in particular, these controllers perform well for processes with benign dynamics and modest performance requirements (Astrom and Hagglund, 1995). It has been stated that 98% of control loops in the pulp and paper industries are controlled by SISO PI controllers (Bialkowski, 1996) and that, in process control applications, more than 95% of the controllers are of PID type (Astrom and Hagglund, 1995).…”