An automatic storage and retrieval system including a storage bin
, having a mechanism for positioning a vehicle at the storage bin including a rough positioning mechanism with an encoder having a rotatable member which rotates through an arc less than a complete revolution in response to movement of the vehicle and generates a signal with a different value at each of various member positions which correspond to respective vehicle rough position zones. A control device receives the signal and selectively causes the vehicle to move to a rough position zone at the storage bin. A fine positioning mechanism repositions the vehicle within a particular position zone after rough positioning and utilizes a light source and photoelectric sensor mounted on the vehicle for detecting a target mounted in a fixed relation with respect to the storage bin. The control mechanism receives an electrical signal generated by the photoelectric sensor and causes the vehicle to stop at the fine position location at the storage bin. A high-low positioning device selectively lowers and raises a carriage including a retrieval apparatus such as a fork assembly within the bin. A method is provided to utilize the automatic storage and retrieval system including rough and fine positioning of a vehicle relative to a storage bin and high-low positioning within the bin.
Automatic storage and retrieval systems are utilized in warehousing to provide maximum efficiency and economy of operation for material handling. An increasing trend toward automation of materials handling functions in warehouses has occured inconjunction with the use of larger storage racks. Such storage racks may, for example, be constructed to heights of 85 feet or more and of virtually unlimited length. A principal advantage to constructing such storage racks to greater heights is thatthe building floor area required to store an equivalent amount of material is thereby reduced in comparison to a system of lesser height.
Referring more in detail to the drawings, the reference numeral 10 generally designates an automatic storage and retrieval system for warehousing material load units 11 which may comprise, for example, a plurality of palletized cases 12containing materials or products. Such material load units 11 may also comprise single items or a plurality of items otherwise suitably grouped or contained. In addition to the normal size material load unit 11, small material load units 13 and largematerial load units 14 may also be handled by the present invention.