Process control using uniform singular value LQG/LTR

O´Dell and Misawa (1995) have proposed a modification to the traditional LQG/LTR design procedure which provides uniform singular values across all frequencies for the target loop. The modification is easy to implement and significantly improves the performance of the LQG/LTR compensator. This paper explores applicability of the technique for distillation column control, the most common multivariable control problem in the process industries. When applied to the Wood/Berry column, performance of the enhanced LQG/LTR compensator is shown to be essentially equivalent to a MAC model predictive controller but without the computational cost associated with on-line optimization. Despite the lack of guaranteed performance and robust stability for nonlinear, nonminimum phase plants, the results suggest further consideration of enhanced LQG/LTR for application in the process industries