In both the ISOPE and LAOO approaches, the reduced gradient is matched.
The LAOO approach of McFarlane and Bacon (1989) uses an approach analogous to the Barrier Function methods used in many primal Interior Point algorithms (Wright, 1997) to deal implicitly with inequality constraints.
ISOPE proved faster than the LAOO approach, due to the formers use of a more structurally accurate model; however, the ISOPE approach exhibits longer term oscillations, which are associated with the plant perturbation scheme used by the method.
There was a significant difference in the Extended Design Cost for the LAOO and ISOPE approaches, yet little difference between theses two methods in terms of their manipulated variable trajectories (cf.
Beyond a disturbance frequency of approximately eight RTO intervals, the LAOO approach yields better performance than the conventional Two-Phase approach.
The ISOPE approach inflates the variance cost significantly more than either the LAOO or QAOO approaches.