Method for turning a rails-mounted lift-robot

A system comprising:

• a plurality of shelving units, each of which comprises a plurality of storage spaces, wherein each shelving units comprise, on a respective vertical plane thereof, a plurality of intersecting vertical and horizontal tracks that are interrupted and absent in intersection regions thereof, wherein each intersection of the plurality of intersecting vertical and horizontal tracks comprises a first corner and a second corner, the first corner is absent of tracks, the second corner comprises continuous tracks connecting a vertical track and a horizontal track;
• one or more robots that are configured to travel on the vertical planes of the shelving units in both a lateral motion mode and a vertical motion mode, wherein the one or more robots are configured to turn in an intersection of the vertical and horizontal tracks by:
• moving in a first motion mode to a first position at the intersection;
• turning over the second corner of the intersection that is accessible from the first position, whereby moving to a second position at the intersection;
• and
• moving in a second motion mode towards a designated direction.