A Modified Active Anti-Disturbance Control for a Nonlinear CSTR Model

Active Anti-Disturbance Control, which so far had reportedly been applied to linear plant models, has been extended in this work to cover control of nonlinear plant models. To accommodate nonlinear plants, an Internal Model Controller (IMC) and a Disturbance Observer (DOB) for nonlinear systems have been used innovatively in the design architecture. It is conjectured that the IMC approach would mitigate plant parameter perturbations whereas the DOB would take care of external disturbances together to conjugatively produce a more robust closed loop plant. To illustrate the proposed algorithm, viz., Modified Active Anti-Disturbance Control (MAADC), the proposed technique has been employed to control a nonlinear Continuous Stirred Tank Reactor (CSTR) system. It is shown that strong external disturbances and model uncertainties have been actively mitigated by using the proposed MAADC, indicating superior robustness compared to ordinary nonlinear IMC based control. Different set-point and disturbance conditions have been considered to characterize the algorithm.