Patent ID: 8607911

Claim:
A movable rack system comprising a plurality of movable racks that can travel freely back and forth on a travel path by means of wheels, where wheels located at both sides in the transverse direction of the travel path are respectively provided with driving motors constituting driven travel wheels, and a control means controls travel of the movable rack by driving the respective driving motors of the movable rack, the system comprising; members to be detected being provided on a floor surface at stop positions of the respective movable racks; and widthwise shift detection means for detecting a widthwise shift of the movable rack from the travel path in the left and right direction perpendicular to the travel path direction by detecting said members to be detected being provided on the respective movable racks; wherein the control means detects a widthwise shift by the widthwise shift detection means when the movable rack stops; if the detected widthwise shift exceeds a pre-determined value, the control means determines a travel route for the movable rack to reduce the widthwise shift, and controls rotation speeds of the respective driving motors so that the movable rack follows the travel route at the next travel thereof.