Application of basis functions to the cross-directional control of web processes

The paper considers three approaches to the cross-directional (CD) control of web processes namely, the direct solution of the partial differential equation (PDE), 2-D polynomial methods and interaction matrix approaches. In each case, the model of the response of the actuators used as the basis of the control design is related back to the underlying PDE description of the process. For the interaction matrix approach, the choice of basis function expansion used to approximate the infinite-dimensional system by a finite-dimensional model is described and the relative merits of the different basis functions are discussed.