The University of British Columbia

This work considers recent theoretical results for dynamical systems distributed in one spatial dimension. An application is presented for an industrial papermaking control system that had been experiencing frequent closed-loop instability problems. Two-dimensional frequency domain analysis uncovered a very small robust stability margin in the region corresponding to qualitative observations of the instability. A two-dimensional loop shaping technique was then used to redesign the feedback controller to obtain a closed-loop system with an acceptable stability margin. The system was observed to remain stable over the course of four days of closed-loop operation.