Actuation cell response and mapping determinations for web forming

Abstract

A standard control signal for a web forming machine is temporarily interrupted and replaced by a perturbing signal or signgals which are applied to one, a grouping, or all of a series of actuation cells of the web forming machine. One or more actuation cells are driven with an alternating perturbing signal(s) which generate a corresponding action in the actuation cell(s). The perturbing signal(s) alternates from a neutral position of the cell and is selected to minimize means effects over any given period of time. The effects of the alternating signal(s) on the web appear within the area of the web which is affected by the actuation cell(s) such that the mapping and the response of the actuation cell(s) can be determined by monitoring that poriton of the web which is formed while the alternating signal(s) is applied to the actuation cell(s). The mapping(s) and/or response(s) of the actuation cell(s) are obtained by correlating the perturbing signal(s) and a web property signal or profile signal obtained by monitoring the web formed by the machine. The perturbing signal(s) is defined by a pseudo-random binary sequence with multiple signals being selected to be statistically independent of one another. To ensure that the web is not perturbed beyond defined specifications, the perturbing signal preferably is gradually increased in amplitude and is terminated individually for each actuation cell upon reaching a usable amplitude.