Web meandering correction system and web meandering correction method

A web meandering correction system comprising:

• an edge detector that detects a position of a widthwise edge of a web and outputs an edge position signal that indicates the position of the widthwise edge;
• an HPF processing unit that executes a high-pass filtering process on the edge position signal using a predetermined lower limit frequency as a reference;
• a high-frequency noise analyzing unit that analyzes high-frequency noise that has passed through the HPF processing unit;
• an LPF processing unit that executes a low-pass filtering process on the edge position signal using a set upper limit frequency as a reference;
• a coefficient setting unit that sets a coefficient that determines the characteristics of the low-pass filtering process, executed by the LPF processing unit, on the basis of a result of analysis performed by the high-frequency noise analyzing unit;
• and
• a meandering correction unit that executes a process for correcting meandering of the web on the basis of information acquired by the LPF processing unit,
• wherein the high-frequency noise analyzing unit includes a noise variance calculating unit that calculates a variance of the high-frequency noise, and
• wherein the coefficient setting unit includes an upper limit frequency setting unit that sets the upper limit frequency on the basis of the variance calculated by the noise variance calculating unit, such that the upper limit frequency is reduced as the variance increases and the upper limit frequency is increased as the variance reduces.