ORTHOGONAL FUNCTIONS FOR CROSS-DIRECTIONAL CONTROL OF WEB FORMING PROCESSES

The cross-directional behaviour of web forming processes can be repres ented in terms of orthogonal basis functions. By choosing a suitable b asis set, it is possible to separate controllable and uncontrollable c omponents of the profile into low- and high-order spectral components and hence obtain a;parsimonious representation. In most cases if there are sufficient actuators to control all low-order spectral components then the interaction matrix is likely to be ill-conditioned, which ne cessitates the incorporation of input constraints into the control des ign. The representation in terms of orthogonal functions allows the de sign of finite-horizon predictive controllers with hard inequality con straints on the input that are computationally feasible for commercial machines. It is also possible to exploit such a representation to con struct efficient estimators for the process.