MULTIRATE MULTIVARIABLE MODEL-PREDICTIVE CONTROL DESIGN

In many chemical processes, not all output measurements and control actions are performed at the same sampling rate. The measurement of gas or liquid concentration, for example, has slow sampling rates compared with temperature and pressure measurement. The model predictive control (MPC) scheme is extended to deal with two multivariable multirate sampled systems. One is a system where every output is measured at the same sampling rate. Input actions are performed at several different sampling rates, all of which are slower than the sampling rate of outputs. The other is a system that has the opposite situation, where every input action is performed at the same sampling rate. Output is measured at different sampling rates, and the measurements are available less frequently than inputs. The features of the control algorithm are thoroughly described. By combining the developed two algorithms, one can control the system so that both outputs measurement and control actions are performed at different sampling rates.