Spatial frequency antiwindup strategy for cross-directional control problems

A MIMO antiwindup strategy for cross-directional control of web forming processes is presented. The scheme relies on a basis function expansion of the system interaction matrix which allows one to analyse the problem in terms of the spatial frequency components of the web profile. Antiwindup protection is achieved by prioritising the control directions in which the available control authority is employed. In particular, disturbance compensation is first sought in those spatial frequency components associated with the largest gain, that is, where the required control effort is smaller. Stability of the scheme is analysed for the case in which complete knowledge of the input and output rotation matrices is assumed. Simulation results show that the steady-state performance attained with the proposed strategy is superior to that achieved by traditional MIMO antiwindup schemes and is close to an optimal QP solution to the problem.