Nonlinear multirate control of a polymerization reactor: an experimental study

A general nonlinear controller design for multivariable multirate systems is presented that changes the manipulated inputs at a faster rate than the output sampling rates. The outputs are incorporated into the algorithm when they become available, with the output predictions based on the latest available measurement. The controller is experimentally applied to a continuous stirred-tank polymerization reactor to regulate the reactor temperature and number averaged molecular weight of the polymer. The performance of the controller was investigated in terms of tracking step changes in the output set points with varying controller parameters. It was shown that the controller represents an efficient and effective method to deal with the problem of multirate output measurements