Proximity detection means on a palletizer hand assembly

A robotic palletizer including a vertical column, a telescoping horizontal arm mounted for vertical movement along the column and a hand assembly mounted at the end of the horizontal arm. A pair of photodetectors, movable with the hand assembly, sense the presence and location of cartons in place on a pallet being loaded and signal the palletizer when the vertical height and horizontal extension of the hand assembly are sufficient to place cartons in the proper position for loading onto the pallet. A circuit controls operation of the palletizer in accordance with the sizes and shapes of the cartons and pallets and permits limited variation of the loading pattern provided by the palletizer. Separate conveyors transport cartons to the palletizer for loading and remove loaded pallets from the palletizer upon completion of the loading cycle.