Robust model predictive control with Zone Control

GONZÁLEZ, ALEJANDRO HERNÁN; ODLOAK, DARCI; MARCHETTI, JACINTO LUIS

IET Control Theory & Applications

The Institution of Engineering and Technology

Año: 2009 vol. 3 p. 121 - 135

1751-8644

MPC is usually implemented as a control strategy where the system outputs are controlled within specified zones, instead of fixed set points. One strategy to implement the zone control is by means of the selection of different weights for the output error in the control cost function. A disadvantage of this approach is that closed-loop stability cannot be guaranteed, as a different linear controller may be activated at each time step. A way to implement a stable zone control is by means of the use of an infinite horizon cost in which the set point is an additional variable of the control problem. In this case, the set point is restricted to remain inside the output zone and an appropriate output slack variable is be included in the optimization problem to assure the recursive feasibility of the control optimization problem. Following this approach, a robust MPC is developed here for the case of multi model uncertainty of open loop stable systems. The controller is devoted to maintain the outputs within their corresponding feasible zone, while reaching the desired optimal input target. Simulation of a process of the oil refining industry illustrates the performance of the proposed strategy