Abstract: A method for turning a pinion-driven lift-robot in an intersection of rails. Moving the pinion-driven lift-robot in a first motion mode to position the pinion-driven lift-robot in a first position at the intersection. The pinion-driven lift-robot is turned over a corner of the intersection that is accessible from the first position and that includes continuous rails connecting a vertical track and a horizontal track, whereby positioning the pinion-driven lift-robot in a second position at the intersection. The pinion-driven lift-robot is moved in a second motion mode towards a designated direction.

Abstract: An inventory handling system (20, 150) includes multiple shelving units (22) for mounting over a horizontal floor (24). Each shelving unit contains a vertical array of shelves (28) on which containers (30) are placed. One or more floor robots (36) travel among the shelving units along first paths on the floor. One or more lift robots (32, 80, 120, 152) move independently of the floor robots along second paths in a vertical plane over vertical faces of the shelving units, and transfer the containers between the shelves and the floor robots.