Rewinding machine for producing paper logs

A rewinder for the production of logs of paper material comprising:

• a winding station for winding the paper material with
• a first winding roller and a second winding roller, delimiting, with their respective external surfaces, a nip through which a paper web comprising one or more paper plies is fed and wound in said winding station to produce logs, and
• a third winding roller which, in relation to a direction from which the paper web is fed, is positioned downstream of the first winding roller and the second winding rollers, wherein the second winding roller is positioned at a lower level than the first winding roller, the axes of rotation of the first winding roller, the second winding roller and the third winding roller are horizontal and parallel to each other such that they are oriented transversely to the direction from which the paper web is fed, the third winding roller is connected to an actuator which allows it to be moved cyclically from and to the nip so that the position of the third winding roller varies in relation to the other two winding rollers during the production of the logs, and wherein each of the said winding rollers rotates around its own axis being connected to a corresponding electric motor, and further comprising
• optical vision system capable of detecting, at a predetermined detection time, an actual position of each log in said winding station and
• an electronic unit which is connected to said optical vision system and is programmed to compare said actual position with a predetermined theoretical position of the logs at said detection time, said electronic unit being connected to at least one electric motor and being also programmed to modify an angular speed of said at least one electric motor when a deviation between said actual position and said theoretical position exceeds a pre-established value, the angular speed of said at least one electric motor is increased or decreased depending on a sign, positive or negative, of said deviation, said electronic unit being also programmed to operate said optical vision system at said detection time.