An autonomous rover including a frame having a first end and a second end longitudinally spaced from the first end and forming a payload bay, the payload bay being sized to support a pickface, a common active registration surface configured to engage the pickface, and a drive section connected to the common active registration surface, the drive section being configured to variably position the common active registration surface relative to at least one storage shelf of an automated storage and retrieval system to effect placement of the pickface on the storage shelf so that pickfaces are substantially continuously arranged along the at least one storage shelf with a predetermined storage spacing between the pickfaces.