Systems and methods are provided for maintaining density and positioning of a grouped sheet articles, such as for feeding of sheet articles from or into the group. One or more pneumatic sensing systems can be used to monitor and control pressure of sheet articles within the group. Dynamic adjustment can be made to the density and position of the sheet articles in the group such as by controlling a motorized belt to move at least a portion of the group of sheet articles in response to an indication to do so from a controller in communication with the pneumatic sensor.