This paper presents the application of a Generalized Pre
dictive Controller (GPC) to sludge density control in a
sugar factory. The loop is controlled by a cascade strategy where both the master and the slave controllers are predic
tive ones. The control law is extremely simple to compute
and the tuning is straightforward since a method to im
plement GPC previously developed by the authors which
is very simple to implement and tune has been used. The
controllers are embedded in the existing control system
needing the same computational requirements as pid rou tines. The original GPC algorithm is improved by the use
of the socalled T polynomial which increases the stabil
ity robustness by ltering the predictions in order to cope
with model uncertainties and di erent process dynamics
caused by changes in the process operating pointsMinisterio de Ciencia y Tecnología s TAP 96-884 (CICYT)Ministerio de Ciencia y Tecnología TAP 95-370 (CICYT
