Controle preditivo de horizonte infinito para sistemas integradores e com tempo morto. / Model predictive control of integrating systems with dead time.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2011

RESUMO

Model Predictive Control (MPC) has gained wide acceptance in chemical industry in the last 30 years. The basic principle of this technique is to use a model to calculate plants future behavior based on the inputs it would receive in the next sampling periods. It must be set an objective, mainly composed of some measure of the distance between plants predicted state and a previously specified condition. Objective value may also include, for example, penalty on control effort necessary to drive the plant closer to the desired state. It is possible to include constraints, such as physical limits of the plant or of the actuators and therefore to pose an optimization problem, searching the best value of the objective function that satisfies all constraints. This work addresses the problem of MPC applied to integrating systems and/or processes with dead-time. These kinds of plants are often difficult to control using only classical techniques. It is presented here a state space model to represent both cases accurately. Measured disturbances may also be incorporated to the model. Finally, it is shown that the proposed controller is stable when its internal model represents exactly plants dynamics. In any real application of this controller, it would be necessary to estimate plants states from outputs measures. In general, Kalman Filter solves this problem. It is studied in this work the effects caused by filters inclusion on closed loop performance. A new observer is proposed, based on a heuristic improvement over Kalman Filter which induces, for some systems, improved performance. Numerical simulation has been performed over a model of an ethylene oxide plant, illustrating the use of this stable controller and the proposed observer.

ASSUNTO(S)

controle preditivo com modelo integrating systems predictive control processes with dead-time processos com tempo morto sistemas integradores

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