Material handling systems with high frequency radio location devices

• US 6,799,099 B2
• Filed: 07/31/2002
• Issued: 09/28/2004
• Est. Priority Date: 08/02/2001
• Status: Expired due to Fees

• Current Assignee: Dematic Corporation
• Original Assignee: Rapistan Systems Advertising Corporation (OSI Systems Incorporated)
• Inventors: Zeitler, David W., Werner, Matt, Koff, Garry
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US10/209,766
• Publication Number:
  US 20030028323A1
• Time in Patent Office: 790 Days
• Field of Search: 701/23, 701/200, 701/201, 701/207, 701/211, 340/998
• US Class Current: 701/23
• CPC Class Codes: G01S 5/0247 Determining attitude
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G05D 1/0282 generated in a local control room

Abstract

A material handling system uses high-frequency location devices for determining the location of mobile units, such as AGVs, overhead mono-rails, conveyor components, or individual articles being transported by such units. The high-frequency location devices may also be used to identify the contents and/or routing information for material being moved within a facility. AGVs may incorporate the high-frequency location devices into their navigation systems to utilize the position and/or heading updates provided by the location devices in guiding the vehicle. The location devices work in cooperation with a number of stationary location devices, such as beacons, that are positioned within the environment at known locations, such as in or adjacent the ceiling of the workplace environment. High-frequency radars may also be used to provide electronic bumpers to the AGVs, allowing them to sense obstacles and take appropriate action to avoid collisions with the obstacles.

Claims

1. A system for determining the location of an automatic guided vehicle, comprising:

a plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable or communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy;

a controller adapted to determine at least a location of said mobile beacon based upon the communications between said stationary beacons and said mobile beacon; and

an incremental sensor adapted to measure changes in the vehicle'"'"'s position wherein said controller uses the measurements from said incremental sensor in combination with the mobile beacon to determine the vehicle'"'"'s position.

2. The system of claim 1 wherein said mobile beacon and said stationary beacons emit ultra-wideband signals.

3. The system of claim 2 further including at least a second mobile beacon positioned on said vehicle at a known location, said controller using mobile beacons to determine the vehicle'"'"'s heading.

4. The system of claim 1 wherein the outputs from said incremental sensor and said mobile beacon are input into a Kalman filter to produce an estimate of the vehicle'"'"'s position.

5. The system of claim 1 wherein said incremental sensor measures the rotations of at least one wheel on said vehicle.

6. The system of claim 5 further including a gyroscope on-board said vehicle.

7. The system of claim 1 wherein said mobile beacon is adapted to determine its position in three dimensions with respect to said plurality of stationary beacons.

8. The system of claim 1 wherein said controller is further adapted to issue commands to steer the vehicle based upon the location of the mobile beacon as determined by the controller.

9. The system of claim 8 wherein said controller determines the position of the vehicle in three dimensions.

10. The system of claim 1 wherein said controller determines the location of said mobile beacon based upon time of flight measurements of signals emitted from at least one of said stationary beacons to said mobile beacon.

11. The system of claim 10 wherein said controller further determines the heading of the vehicle based upon time of flight measurements of multiple signals emitted from at least one of said stationary beacons to said mobile beacons.

12. The system of claim 1 wherein said controller determines the position of said vehicle based upon time of flight measurements of a signal emitted from said mobile beacon to different ones of said stationary beacons.

13. The system of claim 12 wherein said controller further determines the heading of said vehicle based upon time of flight measurements of multiple signals emitted from said mobile beacon to different ones of said stationary beacons.

14. The system of claim 1 wherein said controller determines the heading of said vehicle based upon time of arrival measurements of a signal emitted from said mobile beacon to different ones of said stationary beacons.

15. The system of claim 14 wherein said controller further determines the position of said vehicle based upon time of arrival measurements of multiple signals emitted from said mobile beacon to different ones of said stationary beacons.

16. The system of claim 1 wherein said controller is positioned on-board said automatic guided vehicle.

17. The system of claim 1 wherein each one of said plurality of stationary beacons emit signals that can be differentiated by said mobile unit from other ones of said stationary beacons.

18. The system of claim 1 further including an off-board display adapted to display the position of said automatic guided vehicle.

19. A system for determining the location of an automatic guided vehicle, comprising:

a plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable of communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy; and

a controller adapted to determine at least a location of said mobile beacon based upon communications between said stationary beacons and said mobile beacon; and

a second mobile beacon positioned on-board the vehicle wherein said controller utilizes the mobile beacons to generate an estimate of the vehicle'"'"'s heading.

20. A system for determining the location of an automatic guided vehicle, comprising:

a plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable of communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy;

a controller adapted to determine at least a location of said mobile beacon based upon the communications between said stationary beacons and said mobile beacon; and

a second mobile beacon on-board said vehicle, said mobile beacons being used by said controller to generate an estimate of the vehicle'"'"'s position which is more precise than if only a single one of the mobile beacons on-board said vehicle were used to generate an estimate of the vehicle'"'"'s position.

21. A system for determining the location of an automatic guided vehicle, comprising:

a plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable of communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy; and

a controller adapted to determine at least a location of said mobile beacon based upon the communications between said stationary beacons and said mobile beacon;

wherein said mobile beacon and said plurality of stationary beacons communicate with each other by emitting at least one pulse having a duration of less than one microsecond.

22. The system of claim 21 wherein said mobile beacon and said plurality of stationary beacons communicate with each other by emitting at least one pulse having a duration of less than 100 nanoseconds.

23. A system for determining the location of an automatic guided vehicle, comprising:

a plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable of communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy;

a controller adapted to determine at least a location of said mobile beacon based upon the communications between said stationary beacons and said mobile beacon; and

a second and third mobile beacon positioned on said vehicle at known, separated locations wherein said controller is adapted to determine the vehicle'"'"'s heading based upon the differences in time in which each of the mobile beacons detect a signal from one of said stationary beacons.

24. A system for determining the location of an automatic guided vehicle, comprising:

plurality of stationary high frequency electromagnetic energy emitting and detecting beacons positioned in an area at known locations, said stationary beacons emitting and detecting high frequency radio electromagnetic energy;

at least one mobile electromagnetic energy beacon positioned on-board the automatic guided vehicle, said mobile beacon capable of communicating with said plurality of stationary beacons using high frequency radio electromagnetic energy; and

a controller adapted to determine at least a location of said mobile beacon based upon the communications between said stationary beacons and said mobile beacon;

wherein said vehicle includes multiple mobile beacons positioned on said vehicle at known locations and said controller is adapted to determine the vehicle'"'"'s heading based upon time of arrival measurements of a signal emitted from at least one of said stationary beacons at said mobile beacons.

25. The system of claim 24 wherein controller is further adapted to determine the vehicle'"'"'s position based upon time of arrival measurements of multiple signals emitted from at least one of said stationary beacons at said mobile beacons.

26. A kit for modifying a navigation system of an automatic guided vehicle that uses one or more incremental navigation sensors in combination with at least one fixed reference sensor to estimate the vehicle'"'"'s position, said fixed reference sensor being adapted to detect references positioned at known locations, said kit comprising:

a plurality of electromagnetic energy emitting beacons for positioning at known locations throughout an environment;

at least one electromagnetic energy sensor for positioning on a vehicle, said electromagnetic energy sensor adapted to detect signals emitted from said plurality of electromagnetic energy emitting beacons; and

a controller adapted to use said detected signals in combination with said one or more incremental navigation sensors to generate a position estimate of said vehicle;

wherein said one or more incremental navigation sensors include at least one wheel encoder adapted to measure the number of rotations of at least one wheel on said vehicle.

27. The kit of claim 26 wherein said one or more incremental navigation sensors further includes at least one gyroscope.

28. The kit of claim 26 wherein said controller uses a Kalman filter to estimate the vehicle'"'"'s position based upon said detected signals and said one or more incremental navigation sensors.

29. The kit of claim 26 wherein said electromagnetic energy sensor is adapted to detect ultra-wideband transmissions and said plurality of electromagnetic energy emitting beacons are adapted to emit ultra-wideband transmissions.

30. The kit of claim 26 wherein said controller is further adapted to generate an updated position estimate of the vehicle at least five times per second.

31. The kit of claim 26 wherein said beacons and said sensor are adapted to send wireless messages between themselves.

32. A method of installing an AGV system comprising:

providing a plurality of electromagnetic energy emitting beacons;

providing at least one automatic guided vehicle that includes at least one sensor for detecting transmissions from said plurality of beacons;

placing at least three of said beacons at known locations within an environment;

measuring the location of the at least three beacons within the environment;

placing additional ones of the beacons within the environment;

using the at least three beacons to measure the location of said additional ones of said beacons within the environment; and

communicating the location of said plurality of beacons to said automatic guided vehicle via a wireless transmission; and

programming said at least one automatic guided vehicle to travel along a first pathway.

33. The method of claim 32 further including programming said at least one automatic guided vehicle to travel along a second pathway without having to change the position of any of said beacons, said second pathway being different from said first pathway.

34. The method of claim 32 wherein said environment is a factory, and said method further includes positioning a sufficient number of said beacons throughout the factory in a configuration that enables the automatic guided vehicle to be able to determine its position at substantially any location within the factory.

35. A material handling system comprising:

a plurality of automatic guided vehicles, each of said plurality of automatic guided vehicle including an ultra-wideband communications system;

at least one ultra-wideband transmitter positioned on or adjacent to a load of material to be moved by one of said plurality of automatic guided vehicles, said transmitter adapted to transmit a message to said plurality of automatic guided vehicles indicating that the load of material is to be moved to a destination; and

a controller adapted to determine which of said plurality of automatic guided vehicles is to retrieve said load in response to said message.

36. The system of claim 35 wherein said controller is further adapted to determine which of said plurality of automatic guided vehicles is to retrieve said load based at least partially upon the physical proximity of each of said vehicles to the load.

37. The system of claim 36 wherein each said automatic guided vehicle includes a queue for storing tasks to be performed by the vehicle, and each of said controllers is further adapted to determine which of said plurality of automatic guided vehicles is to retrieve said load based at least partially upon the number of tasks in each vehicle'"'"'s queue.

38. The system of claim of 35 further including a plurality of ultra-wideband beacons positioned at known locations throughout an area through which said vehicles move, and a plurality of ultra-wideband sensors positioned on each of said vehicles, said sensors being adapted to determine their position with respect to said beacons.