Robust cross-directional control of large scale sheet and film processes

Sheet and ®lm processes, which include papermaking, polymer ®lm extrusion, and adhesive coating, are of substantial industrial importance. The processes are poorly conditioned and truly large scale, with up to hundreds of manipulated variables and thou- sands of sensor locations. The uncertainties in sheet and ®lm process models require that they be explicitly taken into account during the control design procedure. Numerically ecient algorithms are developed that provide robust optimal controllers for a wide variety of uncertainty descriptions. The robust optimality of the controllers can be relaxed to provide low order controllers suitable for real time implementation. Robust controllers are designed for a simulated paper machine, based on a realistic descrip- tion of the interactions across the machine, and the level of model inaccuracies.