Web measurement

A method of controlling a process, comprising measuring a web moving in the machine direction with a traversing measuring unit and an array measuring unit, of which

• the traversing measuring unit comprises at least one measuring part that moves in a direction transverse relative to the machine direction and of which
• the array measuring unit comprises at least two measuring parts in a direction transverse relative to the machine direction, the method comprising:
• measuring, with the traversing measuring unit, at least one characteristic of the web with a first radiation type at a plurality of measuring locations during the traversing movement at successive moments in time;
• measuring, with the array measuring unit, at least one characteristic of the web with another radiation type during each traversing movement of the traversing measuring unit at a plurality of different moments in time by measuring the web at each moment in time at a plurality of measuring locations;
• estimating at least one characteristic measured by the traversing measuring unit with at least one measurement of the array measuring unit;
• and
• controlling, based on the estimation result, at least one subprocess effecting at least one characteristic of the web.

A measuring device comprising a traversing measuring unit and an array measuring unit for measuring a web moving in the machine direction;

• the traversing measuring unit comprising at least one measuring part configured to move in a direction transverse relative to the machine direction;
• the array measuring unit comprising at least two measuring parts successively in a direction transverse relative to the machine direction, and
• one measuring part of the traversing measuring unit is configured to measure at least one characteristic of the web with a first radiation type from a plurality of measuring locations during the traversing movement at successive moments in time;
• at least two measuring parts of the array measuring unit are configured to measure at least one characteristic of the web with another radiation type during each traversing movement at a plurality of different moments in time by directing the measurement to a plurality of measuring locations in the web at each moment in time;
• and
• a signal processing unit is configured to estimate at least one characteristic measured by the traversing measuring unit with at least one measurement of the array measuring unit.

A control apparatus for controlling a process, the control apparatus comprising a traversing measuring unit and an array measuring unit for measuring a web moving in the machine direction;

• the traversing measuring unit comprises at least one measuring part configured to move in a direction transverse relative to the machine direction;
• the array measuring unit comprises at least two measuring parts successively in a direction transverse relative to the machine direction, and
• one measuring part of the traversing measuring unit is configured to measure at least one characteristic of the web with a first radiation type from a plurality of measuring locations during the traversing movement at successive moments in time;
• at least two measuring parts of the array measuring unit are configured to measure at least one characteristic of the web with another radiation type during each traversing movement at a plurality of different moments in time by directing the measurement to a plurality of measuring locations in the web at each moment in time;
• a signal processing unit is configured to estimate at least one characteristic measured by the traversing measuring unit with at least one measurement of the array measuring unit;
• and
• a controller is configured to control, based on the estimation result, at least one subprocess affecting at least one characteristic of the web.