Tiered control architecture for material handling

• US 7,568,572 B2
• Filed: 09/27/2007
• Issued: 08/04/2009
• Est. Priority Date: 06/07/2001
• Status: Expired due to Fees

• Current Assignee: Dematic Corporation
• Original Assignee: Dematic Corporation
• Inventors: Ko, Clyde Miin-Arng, Black, Andrew R., Zeitler, David W
• Primary Examiner(s): Crawford; Gene
• Assistant Examiner(s): BURGESS, RAMYA PRAKASAM
• Application Number:
  US11/862,678
• Publication Number:
  US 20080017476A1
• Time in Patent Office: 677 Days
• Field of Search: 700/213, 700/230, 198/370.01, 198/370.02, 198/718, 198/736, 198/741
• US Class Current: 198/370.02
• CPC Class Codes: B65G 2207/36 Pushing shoes on conveyors
• CPC Class Codes: B65G 47/52 Devices for transferring articles or materials between conveyors i.e. discharging or feeding devices loading or unloading by means not incorporated in, or not operatively associated with, conveyors B65G65/00; transfer of workpieces during metal rolling B21B41/00
• CPC Class Codes: B65G 47/844 the article-engaging elements being pushers transversally movable on the supporting surface, e.g. pusher-shoes
• CPC Class Codes: G05B 19/4182 manipulators and conveyor only
• CPC Class Codes: G05B 2219/33342 Master slave, supervisor, front end and slave processor, hierarchical structure
• CPC Class Codes: G05B 2219/36371 Barcode reader
• CPC Class Codes: G05B 2219/37094 Hall sensor
• CPC Class Codes: G05B 2219/37555 Camera detects orientation, position workpiece, points of workpiece
• CPC Class Codes: G05B 2219/37572 Camera, tv, vision
• CPC Class Codes: G05B 2219/39102 Manipulator cooperating with conveyor
• CPC Class Codes: G05B 2219/45054 Handling, conveyor
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A control architecture for material handling includes multiple tiers of controllers, such as three. The lowest-level controllers interact directly with sensors and actuators used in the material handling system, such as photo-eyes and motors used with conveyors. The lowest-level controllers receive higher level commands from one or more mid-level controllers. The mid-level controllers, in turn, receive still higher level commands and information from at least one upper level controller. Each mid and low level controller is designed to include sufficient intelligence to deal with many of the signals and messages it receives without having to forward those signals or messages to the next higher level controller and await instructions from that higher level controller. The system thus distributes intelligence amongst the controllers. The system is well-adapted for application to conveyor control systems.

Claims

1. A method of controlling a conveyor sortation system comprising:

providing a sortation bed having a conveying surface movable in a direction of conveyance;

providing an induct conveyor adapted to induct articles for delivery to said sortation bed;

providing a merge conveyor for merging a plurality of conveying lines;

providing a merge and induct manager adapted to control a speed of said induct conveyor and said merge conveyor;

providing a first controller adapted to control said merge and induct manager;

providing a second controller adapted to determine an article'"'"'s position on said conveying surface, said second controller responsive to said first controller;

providing a plurality of third controllers and a plurality of associated divert switches, each said third controller adapted to control an associated divert switch for selectively diverting articles off of said sortation bed;

sending an article'"'"'s intended destination from said first controller to said second controller;

selecting one of said plurality of third controllers based on the article'"'"'s intended destination; and

sending an article'"'"'s location on the conveying surface from said second controller to said selected third controller and instructing said selected third controller to divert said article when said location reaches the associated divert switch.

2. The method of claim 1 further comprising:

providing a motor adapted to move said conveying surface;

providing a fourth controller adapted to control said motor; and

sending a command from said second controller to said fourth controller to cause said motor to operate at a particular speed.

3. The method of claim 1 further comprising determining whether any of said divert switches have malfunctioned and sending a message from the associated third controller to said second controller indicating such a malfunction.

4. The method of claim 2 further comprising determining whether said motor has malfunctioned and sending a message from the associated fourth controller to said second controller indicating such a malfunction.

5. The method of claim 1 further comprising providing microprocessors in each of said first, second, and third controllers.

6. The method of claim 1 further comprising providing a plurality of movable slats on said sortation bed and providing a plurality of pushers movable along said slats in a direction generally transverse to the direction of conveyance, said divert switches adapted to selectively cause said pushers to move in said transverse direction.

7. The method of claim 1 further including automatically assigning a communications address to each of said plurality of third controllers and storing said automatically assigned address in said third controllers and said second controller.

8. The method of claim 7 wherein automatically assigning a communications address to each of said plurality of third controllers includes transmitting an initial command from said second controller to all of said third controllers wherein said initial command causes said third controllers to respond to said second controller at non-overlapping time periods.

9. The method of claim 8 wherein said non-overlapping time periods are defined by reference to movement of said conveying surface of said sortation bed.

21. The method of claim 1 further including:

providing a gap manager adapted to control spacing between articles delivered to said sortation bed; and

controlling said gap manager with said first controller.

10. A conveyor sortation system comprising:

a sortation bed having a conveying surface movable in a direction of conveyance;

an induct conveyor adapted to induct articles for delivery to said sortation bed;

a merge conveyor for merging a plurality of conveying lines;

a merge and induct manager adapted to control a speed of said induct conveyor and said merge conveyor;

a first controller adapted to control said merge and induct manager;

a second controller adapted to determine an article'"'"'s position on said conveying surface, said second controller reponsive to said first controller; and

a plurality of third controllers and a plurality of associated divert switches, each of said third controllers adapted to control an associated divert switch for selectively diverting articles off of said sortation bed, wherein said first controller is further adapted to send the article'"'"'s intended destination to said second controller and said second controller is further adapted to select one of said plurality of third controllers based upon the article'"'"'s destination and send the article'"'"'s location on the conveying surface to said selected third controller along with an instruction to said third controller to divert the article when the article'"'"'s location reaches the associated divert switch of the selected third controller.

11. The system of claim 10 wherein said first controller does not maintain information on the position of any articles on the conveying surface.

12. The system of claim 10 further including a motor and an associated motor controller for controlling said motor wherein said second controller is further adapted to send a command to said motor controller to cause said motor to operate at a particular speed.

13. The system of claim 10 further including a sensor adapted to detect whether any of said divert switches actually diverted an article off of said sortation bed.

22. The system of claim 10 further including a gap manager adapted to control spacing between articles delivered to said sortation bed wherein said first controller is adapted to control said gap manager.

14. A conveyor system comprising:

a sortation bed having a conveying surface movable in a direction of conveyance;

a plurality of divert switches associated with said sortation bed, said divert switches adapted to divert articles off of said sortation bed;

a plurality of divert modules, each said divert module adapted to control at least one of said divert switches;

a divert controller adapted to control and communicate with each of said divert modules, said divert controller further adapted to transmit an auto-addressing command to each of said divert modules wherein each of said divert modules responds to said auto-addressing command at non-overlapping times and said divert controller uses the responses of said divert modules to automatically assign a unique communications address to each of said divert modules.

15. The system of claim 14 wherein said divert modules respond to said auto-addressing command at times determined by movement of a detectable element associated with said conveying surface.

16. The system of claim 15 wherein said detectable element is a magnet moveable with said conveying surface.

17. The system of claim 15 wherein said conveying surface is defined by a plurality of generally parallel slats, each of said slats is associated with a unique identifier, and each of said divert modules are able to determine when a slat having a particular identifier is aligned with a particular divert switch controlled by said divert module.

18. The system of claim 15 further including a controller in communication with said divert controller, said controller adapted to be able to determine an article'"'"'s intended destination and communicate said intended destination to said divert controller wherein said divert controller uses said intended destination to determine which of said divert modules to send instructions to in order to divert the article so that it reaches its intended destination.

19. The system of claim 18 wherein said controller does not send commands to any of said divert modules.

20. The system of claim 14 further including a motor and an associated motor controller for controlling said motor wherein said divert controller is further adapted to send a command to said motor controller to cause said motor to operate at a particular speed.