Distributed control systems and methods that selectively activate respective coordinators for respective tasks

• US 7,873,962 B2
• Filed: 04/08/2005
• Issued: 01/18/2011
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Crawford, Lara S., Roufas, Kimon D., Eldershaw, Craig, Hindi, Haitham A., Ruml, Wheeler, Fromherz, Markus P. J.
• Primary Examiner(s): Bullock, Jr.; Lewis A
• Assistant Examiner(s): To; Jennifer N
• Application Number:
  US11/102,910
• Publication Number:
  US 20060230403A1
• Time in Patent Office: 2,111 Days
• Field of Search: 718/100, 718/103, 718/102, 718/104, 718/106, 711/118, 709/201, 709/208, 700/100, 700/213, 700/287, 700/2, 700/9, 700/127, 700/129, 705/43, 358 115- 116
• US Class Current: 718/106
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32297 Adaptive scheduling, feedback of actual proces progress to adapt schedule
• CPC Class Codes: G05B 2219/33273 DCS distributed, decentralised controlsystem, multiprocessor
• CPC Class Codes: G05B 2219/45187 Printer
• CPC Class Codes: G06F 3/1296 Printer job scheduling or printer resource handling
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

Respective coordinators are spawned or activated to coordinate activities with regard to respective tasks. Where the respective tasks require cooperative efforts of a plurality of controllers, the respective coordinators ensure cooperative efforts by generating and communicating cooperative commands to the plurality of controllers. The coordinators may act as clearinghouses for system data, selectively requesting and relaying system information to appropriate controllers. For example, a document processing system activates respective coordinators for respective sheets of print media. The respective coordinators orchestrate the transportation of the sheets by sequentially orchestrating the activities of sequentially selected pluralities of transportation actuator controllers. Selected sheet position information from sensors and/or from models maintained by the actuator controllers may be relayed by the coordinators to selected actuator controllers as appropriate to the sheet transportation tasks.

Claims

1. A method for coordinating controllers in a distributed control system that is operative to perform a plurality of simultaneous tasks, the method comprising:

determining, by a supervisory element, respective tasks of the plurality of simultaneous tasks to be performed;

activating, by the supervisory element, respective coordinators in association with the respective tasks, the respective coordinators comprising software elements run on or by at least one computational platform, the respective coordinators then each;

identifying a plurality of respective subtasks to be performed in order to complete the respective tasks;

identifying, based on the identified respective subtasks, a plurality of respective controllers, for controlling a plurality of actuators to perform the respective subtasks;

generating respective commands for directing the performance of the respective plurality of subtasks;

communicating the respective commands to the respective controllers as appropriate to the respective subtasks;

collecting respective progress information from at least one respective information source; and

communicating the respective progress information to the respective controllers as appropriate to the respective subtasks.

2. The method of claim 1 further comprising:

deactivating, by at least one of the respective coordinators, respective controllers as respective subtasks are determined to be completed based on the collected respective progress information, thereby releasing the respective controllers to execute commands communicated from another coordinator associated with another task.

3. The method of claim 1 further comprising:

deactivating at least one respective coordinator when the respective task of the at least one coordinator is determined to be completed.

4. The method of claim 1 further comprising:

maintaining at least one model of the respective subtasks; and

deactivating at least one of the coordinator and the respective controllers when the respective subtasks are completed according to the at least one model.

5. The method of claim 1 further comprising:

Identifying by at least one of the respective coordinators, at least one respective information source that is able to provide progress information regarding a performance of the respective subtasks.

6. The method of claim 5 wherein identifying at least one respective information source comprises:

at least one of identifying at least one feedback variable from at least one controller and identifying at least one sensor.

7. The method of claim 1 further comprising:

maintaining at least one of a command model of the respective task based on the communicated respective commands and a progress model of the respective task based on the collected respective progress information.

8. The method of claim 1 further comprising:

maintaining a command model of the respective task based on the communicated respective commands;

maintaining a progress model of the respective task based on the collected respective progress information;

comparing a first indicated status of the respective task from the progress model to a second indicated status from the command model, thereby generating a respective task progress error value; and

comparing the respective task progress error value to a respective task progress error limit; and

performing an error task if the respective task progress error value is beyond the respective task progress error limit.

9. The method of claim 8 wherein performing the respective error task comprises:

generating at least one of a respective error message identifying the respective task and describing the respective task progress error and at least one updated command message for correcting or compensating for a respective task progress error associated with the respective task progress error value.

10. A system comprising:

at least one supervisory element, run by a computational platform, that is operative to generate respective task descriptions describing respective tasks, to activate respective coordinators to be responsible for orchestrating a completion of the respective tasks and to communicate the respective task descriptions to the respective coordinators;

a plurality of controllers that are operative to control a plurality of actuators according to respective subtask descriptions received from the respective coordinators; and

a plurality of information sources that are operative to report status information regarding respective progress of respective tasks to the respective coordinators;

wherein the respective coordinators are operative to receive the respective task descriptions, identify, based on the respective task descriptions, a plurality of respective subtasks to be performed in order to complete the task, identify, based on the respective subtasks, a subset of the plurality of respective controllers, for controlling a subset of the plurality of actuators to perform the respective subtasks, generate respective commands for performing the respective plurality of subtasks, communicate the respective commands to the respective controllers as appropriate to the respective subtasks, collect the respective progress information from the respective subsets of information sources and communicate the respective progress information to the respective controllers as appropriate to the respective subtasks.

11. The system of claim 10 wherein the respective coordinators are further operative to monitor the respective progress of the respective subtasks.

12. The system of claim 11 wherein the respective coordinators are further operative to deactivate the respective controllers as the subtasks are completed.

13. The system of claim 10 wherein the respective coordinators are further operative to report the respective progress of the respective tasks to the supervisor and wherein the supervisor is further operative to deactivate the respective coordinators when the respective tasks are completed.

14. The system of claim 10 wherein the at least one supervisory element is operative to activate the respective coordinators by spawning or instantiating the respective coordinators.

15. The system of claim 10 wherein the supervisor is operative to activate the respective coordinators by communicating respective task descriptions to respective idle coordinators.

16. The system of claim 10 wherein the plurality of controllers comprises:

at least one of a transport actuator controller, a nip controller, a feeder controller, finisher controller and a marking engine controller.

17. The system of claim 10 wherein the plurality of actuators comprises:

at least one of a xerographic marking engine actuator, a transport actuator, a nip driver, a feeder actuator and a finisher actuator.

18. The system of claim 10 wherein the respective coordinators are operative to identify respective subsets of the plurality of information sources that are able to provide progress information regarding the performance of the respective subtasks by at least one of identifying at least one sensor and identifying at least one feedback variable from at least one controller of the plurality of controllers.

19. The system of claim 11 wherein the respective coordinators are operative to monitor the respective progress of the respective subtasks by at least one of maintaining a command model of the task based on the communicated respective commands and maintaining a progress model of the task based on the respective progress information.

20. The system of claim 11 wherein the respective coordinators are operative to monitor the respective progress of the respective subtasks by maintaining respective models of the respective tasks based on the communicated respective commands and maintaining respective progress models of the respective tasks based on the respective progress information and wherein the respective coordinators are further operative to compare respective first indicated statuses of the respective tasks from the progress model to respective second indicated statuses of the respective tasks from the command based model, thereby generating respective task progress error values, to compare the respective task progress error values to respective task progress error limits and to perform respective error tasks if the respective task progress error values are beyond the respective error limits.

21. A method for processing a sheet in a document processing system, the method comprising:

receiving at a supervisory element, a sheet description specifying a document processing job to be performed on the sheet;

activating by the supervisory element, a coordinator as a proxy for the sheet, the coordinator then;

identifying a plurality of respective subtasks to be performed in order to process the sheet according to the sheet description;

identifying, based on the identified respective subtasks, a plurality of respective controllers for controlling a plurality of actuators to perform the respective subtasks;

generating respective commands for directing the respective plurality of subtasks;

communicating the respective commands to the respective controllers as appropriate to the respective subtasks;

collecting respective progress information from at least one respective information source;

communicating the respective progress information to the respective controllers as appropriate to the respective subtasks;

estimating the respective progress of the respective subtasks;

deactivating the respective controllers as the subtasks are completed; and

deactivating by the supervisory element, the coordinator when the task is completed.

22. A document processing system comprising:

a first xerographic marking engine;

a transportation system that is operative to transport sheets of print media to and/or from the first engine, the transportation system including a plurality of transport actuators,

at least one supervisory element that is operative to generate respective sheet processing task descriptions describing respective sheet processing tasks and to activate respective sheet coordinators to be responsible for orchestrating the respective sheet processing tasks according to the respective sheet processing task descriptions;

a plurality of respective transport controllers that are operative to control respective sets of transport actuators, of the plurality of transport actuators, according to respective sheet processing subtask descriptions received from the respective sheet coordinators;

a first marking module controller that is operative to control aspects of processing of the first marking engine according to respective sheet processing subtask descriptions received from the respective sheet coordinators, and

a plurality of information sources that are operative to report status information regarding respective progress of respective sheet processing tasks to the respective sheet coordinators;

wherein the respective sheet coordinators are operative to receive the respective sheet processing task descriptions, identify, based on the respective sheet processing task descriptions, a plurality of respective sheet processing subtasks to be performed in order to complete the respective sheet processing tasks, identify, based on the respective sheet processing subtasks, a subset of the plurality of respective transport controllers and the first marking module controller, for controlling a subset of the plurality of transport actuators and the first marking engine to perform the respective sheet processing subtasks, identify respective subsets of the plurality of information sources that are able to provide progress information regarding the performance of the respective sheet processing subtasks, generate respective commands for performing the respective plurality of sheet processing subtasks, communicate the respective commands to the respective transport controllers and/or first marking engine controller as appropriate to the respective subtasks, collect the respective progress information from the respective subsets of information sources and communicate the respective progress information to the respective transportation controllers and/or first marking engine controller as appropriate to the respective sheet processing subtasks.

23. The document processing system of claim 22 wherein the plurality of transport controllers comprises:

at least one of a nip controller, an air jet controller, a flipper controller and a spherical nip controller.

24. The document processing system of claim 22 further comprising:

at least a second marking engine;

at least a second marking module controller that is operative to control aspects of processing of the at least a second marking engine according to respective sheet processing subtask descriptions received from the respective sheet coordinators,

wherein the transportation system is further operative to transport sheets of print media to and/or from the at least a second marking engine; and

wherein the respective sheet coordinators are further operative to identify, based on the respective sheet processing subtasks, at least a respective one of the at least a second marking module controller, for controlling at least a respective one of the at least a second marking engine to perform the respective sheet processing subtasks, and communicate the respective commands to at least a respective one of the at least a second marking module controller as appropriate to the respective subtasks.

25. A method for coordinating controllers in a distributed control system that is operative to simultaneously perform operations on a plurality of workpieces, the method comprising:

activating, by a supervisory element, a respective coordinator for each respective workpiece, wherein each respective coordinator encompasses knowledge regarding an itinerary of operations to be applied to the respective workpiece, each respective coordinator thereby;

issuing respective commands to a series of actuator controllers for directing the series of actuators to perform respective operations on the respective workpiece according to the itinerary;

maintaining at least one respective estimate of progress of the respective operations performed on the respective workpiece; and

deactivating the respective coordinator when the itinerary of operations is completed.