Platform assembly for use with sorting articles comprises platforms connected to each other to form at least one level surface for transit thereabout by a plurality of vehicles. Each platform defines a first orientation in which the platform is in a retracted position and a second orientation in which the platform is in an extended position with a horizontal disposition. Each platform includes a first panel comprising a plurality of markers thereon, the markers forming a grid on the first panel for transit thereabout by the plurality of vehicles. Each marker includes a magnetic signature for determining an orientation of the marker. A container is positioned about at least one of the plurality of markers. In operation, the vehicle is directed by a control system to deposit an article carried thereon into a container associated with a marker based on the location and orientation of the marker.