Material handling method using autonomous mobile drive units and movable inventory trays

• US 20040010337A1
• Filed: 02/03/2003
• Published: 01/15/2004
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Distrobot Systems, Inc. (Amazon.com, Inc.)
• Inventors: Mountz, Michael C.
• Granted Patent: US 6,748,292 B2
• Time in Patent Office: Days
• US Class Current: 700/214
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0236 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0257 using a radar radar systems designed for anti-collision purposes between land vehicles or between land vehicle and fixed obstacles G01S13/931
• CPC Class Codes: G05D 1/0259 using magnetic or electromagnetic means
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS
• CPC Class Codes: G05D 1/0297 by controlling means in a control room
• CPC Class Codes: G05D 2201/0216 Vehicle for transporting goods in a warehouse, factory or similar

Abstract

An inventory system includes a plurality of mobile drive units with a processor control and with a positioning system that enables the mobile drive units to navigate a factory floor. The mobile drive units interface with a material handling system to receive order requests and deliver inventory items to pack stations located on the factory floor. The inventory items are stored in trays stacked into movable inventory pods, which may be transported by the mobile drive units throughout the factory floor. The mobile drive units dock and undock with the movable inventory pods using a docking mechanism. The movable inventory pods are stored in a virtual storage grid when they are not being transported by the mobile drive units. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Claims

1. A method for managing items of inventory in a warehouse comprising:

sending a request signal from a computer, the request signal specifying an item of inventory;

receiving the request signal by a mobile drive unit (MDU), the MDU responding to the request signal by;

determining a location of a movable inventory pod (MIP) that contains the item of inventory;

energizing a drive mechanism of the MDU to move the MDU to the location of the MIP;

docking the MDU to the MIP;

energizing the drive mechanism of the MDU to transport the MIP to a station of the warehouse.

2. The method of claim 1 wherein the station comprises a pack station.

3. The method of claim 1 wherein the MIP comprises one of a plurality of MIPs located in the warehouse.

4. The method of claim 1 wherein sending is performed via wireless transmission.

5. The method of claim 1 wherein the MDU comprises a random-access memory (RAM) that stores data that includes position coordinates of the MIPs and the items of inventory contained in the MIPs.

6. The method of claim 5 wherein the MDU further comprises a processor used to calculate movements and process communication messages.

7. The method of claim 1 further comprising:

generating position signals by a guidance system of the MDU; and

navigating a path to the MIP using the position signals.

8. The method of claim 7 further comprising navigating a path to the station using the position signals generated by the guidance system.

9. The method of claim 1 further comprising storing the items of inventory in a plurality of MIPs located in the warehouse.

10. The method of claim 1 wherein the MIPs are configured as vertically stackable trays, each tray containing one or more items of inventory.

11. The method of claim 10 wherein each tray may be subdivided into bins.

12. The method of claim 1 further comprising:

storing the plurality of MIPs in a virtual grid on a floor of the warehouse;

embedding a radio frequency identification (RFID) chip in each of the MIPs, the RFID chip identifying a unique MIP and the items of inventory contained in each MIP.

13. A computerized method for managing items of inventory in a warehouse comprising:

transmitting a request signal from a computer, the request signal specifying an order for an item of inventory;

receiving the request signal by a plurality of mobile drive units (MDUs) located in the warehouse, each of the MDUs including a processor coupled to a random-access memory (RAM) that stores position coordinates of a plurality of movable inventory pods (MIPs) and a list of inventory items contained in each of the MIPs;

selecting a particular MDU to fulfill the order;

driving the MDU to the location of a MIP that contains the item of inventory;

docking the particular MDU with the MIP;

driving the particular MDU to transport the MIP to a pack station.

14. The computerized method of claim 13 wherein the selecting of a particular MDU comprises:

determining by each of the MDUs an estimated time duration to transport a movable inventory pod containing the item specified in the order to the pack station.

15. The computerized method of claim 14 further comprising:

transmitting by each of the MDUs, the estimated time duration to the pack station; and

identifying the particular MDU to fulfill the order request based on a shortest estimated time duration.

16. The computerized method of claim 13 further comprising:

transmitting an availability signal to the pack station.

17. The computerized method of claim 13 wherein the pack station comprises one of a plurality of pack stations, each of which transmits request signals specifying an order for items of inventory to the MDUs, and further comprising:

selecting, by an idle MDU an order from a particular pack station according to a priority algorithm.

18. The computerized method of claim 13 wherein the transmitting is performed via wireless transmission.

19. The computerized method of claim 13 wherein the MDU comprises a random-access memory (RAM) that stores data that includes position coordinates of the MIPs and the items of inventory contained in the MIPs.

20. The computerized method of claim 19 wherein the MDU further comprises a processor used to calculate movements and process communication messages.

21. The computerized method of claim 13 further comprising:

generating position signals by a guidance system of the MDU; and

navigating a path to the MIP using the position signals.

22. The computerized method of claim 21 further comprising navigating a path to the pack station using the position signals generated by the guidance system.

23. The computerized method of claim 13 further comprising storing the items of inventory in a plurality of MIPs located in the warehouse.

24. The computerized method of claim 13 wherein the MIPs are configured as vertically stackable trays, each tray containing one or more items of inventory.

25. The computerized method of claim 13 further comprising:

storing the plurality of MIPs in a virtual grid on a floor of the warehouse;

embedding a radio frequency identification (RFID) chip in each of the MIPs, the RFID chip identifying a unique MIP and the items of inventory contained in each MIP.

26. The computerized method of claim 13 further comprising:

removing the item of inventory from the MIP at the pack station;

moving the MDU to return the MIP to an available storage location;

returning the MIP to an available storage location in the warehouse;

undocking the MDU from the MIP.

27. The computerized method of claim 13 further comprising:

moving the MDU to a check-in station;

replenishing items of inventory to the MIP at the check-in station;

returning the MIP to an available storage location in the warehouse;

undocking the MDU from the MIP.

28. A method for managing items of inventory in a warehouse comprising:

sending a request signal from a Material Handling System (MHS) to a computer at a pack station in a warehouse, the request signal specifying an item of inventory;

receiving the request signal by a plurality of mobile drive units (MDUs) located in the warehouse, each of the MDUs including a processor coupled to a random access memory (RAM) that stores position coordinates of a plurality of movable inventory prods (MIPs) and a list of inventory items contained in each of the MIPs;

determining by each of the MDUs an estimated time duration to transport a MIP containing the item specified in the request signal;

selecting by the computer at the pack station a MDU to fulfill the order based on the shortest estimated time duration;

driving the MDU to the location of a MIP that contains the item of inventory;

docking the MDU with the MIP;

driving the MDU to transport the MIP to a pack station.

29. The method of claim 28 wherein the selecting is performed via wireless transmission.

30. The method of claim 28 wherein the pack station comprises one of a plurality of pack stations, a computer at each of the pack stations transmitting a request signal to the plurality of MDUs via wireless transmission.

31. The method of claim 28 wherein the MDU comprises a random-access memory (RAM) that stores data that includes position coordinates of the MIPs and the items of inventory contained in the MIPs.

32. The method of claim 28 wherein the MDU further comprises a processor used to calculate movements and process communication messages.

33. The method of claim 28 wherein the MIPs are configured as vertically stackable trays, each tray containing one or more items of inventory.

34. The method of claim 28 further comprising:

generating position signals by a guidance system of the MDU; and

navigating a path to the MIP using the position signals.

35. The method of claim 34 further comprising navigating a path to the pack station using the position signals generated by the guidance system.

36. The method of claim 28 further comprising:

storing the plurality of MIPs in a virtual grid on a floor of the warehouse;

embedding a radio frequency identification (RFID) chip in each of the MIPs, the RFID chip identifying a unique MIP and the items of inventory contained in each MIP.

37. The method of claim 28 further comprising:

removing the item of inventory from the MIP at the pack station;

moving the MDU to return the MIP to an available storage location;

returning the MIP to an available storage location in the warehouse;

undocking the MDU from the MIP.

38. The method of claim 28 further comprising:

moving the MDU to a check-in station;

replenishing items of inventory to the MIP at the check-in station;

returning the MIP to an available storage location at the warehouse;

undocking the MDU from the MIP.

39. The method of claim 28 further comprising communicating information among peer MDUs using the wireless network.

40. The method of claim 39 wherein the information includes coordinate information for each of the MDUs and information about inventory items stored in particular MIPs.

41. The method of claim 28 further comprising transmitting information to the MHS by one or more of the MDUs using the wireless network, the information including coordinate information for each of the MDUs and information about inventory items stored in particular MIPs.

42. The method of claim 41 further comprising:

receiving the information by the MHS; and

transmitting the information received from the one or more of the MDUs to the plurality of the MDUs using the wireless network.

43. A computer-implemented method for managing items of inventory in a warehouse comprising:

transmitting position coordinates of one or more movable inventory pods (MIPs) and one or more mobile drive units (MDUs) to a computer;

receiving, by the computer, an order request for an item of inventory;

selecting, by the computer, a particular MDU to fulfill the order request;

transmitting the order request to the particular MDU;

docking the particular MDU to an MIP containing the item of inventory; and

moving, by self-power of the particular MDU, the MIP to a pack station located in the warehouse.

44. The method of claim 43 wherein transmitting the order request is performed via wireless transmission.

45. The method of claim 43 wherein selecting a particular MDU from the one or more MDUs is performed via a software algorithm in the computer.

46. The method of claim 43 further comprising:

receiving information by a particular MDU from an RFID chip embedded in each MIP, the information identifying items of inventory contained by each MIP; and

transmitting the information by the MDU to the computer via a wireless network.

47. The method of claim 43 further comprising:

removing the item of inventory from the MIP at the pack station;

directing the MDU to return the MIP to an available storage location;

returning the MIP to an available storage location in the warehouse;

undocking the MDU from the MIP.

48. The method of claim 43 further comprising storing the MIPs in a virtual grid on a factory floor.

49. The method of claim 48 wherein the returning of the MIP to an available storage location comprises determining an optimum storage location for the MIP in the virtual grid according to an algorithm stored in the computer.

50. The method of claim 43 further comprising:

receiving a request to replenish an item of inventory by the computer;

transmitting the request to a MDU selected by the computer;

moving the MDU to a check-in station; and

replenishing the item of inventory in a MIP docked to the MDU at the check-in station.

52. The method of claim 43 further comprising communicating in a peer-to-peer fashion between each of the MDUs to form queues and to avoid traffic congestion on a factory floor.

53. The method of claim 43 further comprising polling the one or more MDUs on a continual basis to determine updated position coordinates of the MDUs.

54. The method of claim 43 further comprising transmitting the location of each MDU by each MDU in regular intervals to the computer to maintain updated position coordinates of each of the MDUs.