Robotic warehouse

A storage facility comprising:

• a plurality of shelving units each comprising a plurality of storage levels differing from one another by height from above a floor of the storage facility;
• a first plurality of robotic carriers configured to carry deliverables between the plurality of storage levels;
• a second plurality of robotic carriers configured to carry deliverables between low-level locations leveled no more than a predetermined height above the floor of the storage facility, wherein storage locations within a predetermined number of storage levels from above the low-level locations, are beyond the reach of robotic carriers from said second plurality;
• a picking station;
• a computerized mission planning center configured to control transfer of deliverables between locations in the storage facility, by the first plurality and the second plurality of the robotic-carriers;
• wherein robotic carriers of the first plurality are of simplified structure in that each robotic carrier from said first plurality is configured to carry deliverables situated on the robotic carrier from above on a horizontally maintained platform, the robotic carrier being thereby secured against unintentional dropping of the tote;
• and
• wherein the mission planning center is configured to provide for a transfer of a tote of interest from the top of a robotic carrier of the first plurality to a robotic carrier of the second plurality, or from a robotic carrier of the second plurality to the top of a robotic carrier of the first plurality, by first instructing a robotic carrier which already carries the tote of interest, to unload the tote onto an intermediating platform accessible to a robotic carrier of the second plurality, and upon unload approval, instructing a robotic carrier intended to receive the tote, to upload the tote of interest from the intermediating platform.