ON OPTIMIZING CONTROL AND THE EFFECT OF DISTURBANCES - CALCULATION OFTHE OPEN-LOOP BACKOFFS

An algorithmic approach is presented for determining the necessary ope n-loop back-offs from a steady-state optimum, so as to ensure that dis turbances cause no constraint violation. The approach consists of defi ning a joint optimisation-flexibility problem that can be solved withi n an optimisation framework based on a cutting-plane approach. After c alculating the open-loop back-off cost over the disturbance range of i nterest, bounds on the value of closed-loop control may be found by se lecting the worst economics for the uncontrolled case.