PARALLEL CASCADE NONLINEAR CONTROL OF NONLINEAR-SYSTEMS - APPLICATION TO AN UNSTABLE BIOREACTOR

The design of a model reference parallel cascade nonlinear controller is analyzed for an unstable continuous stirred tank bioreactor (CSTBR) which is represented by a nonlinear system x = f(x) + g(x, d) u, y = cx. Integral and derivative control actions are incorporated in the control law. Theoretical analysis on the robustness of the proposed control scheme under process/model parameter uncertainly is provided. The method is applied theoretically to the substrate concentration control of a CSTBR which has severe nonlinearity and steady-state multiplicity.