Apparatus and a method for controlling the release of jobs from a pool of pending jobs into a factory

• US 4,956,784 A
• Filed: 12/14/1988
• Issued: 09/11/1990
• Est. Priority Date: 12/14/1988
• Status: Expired due to Fees

• Current Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Original Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Inventors: Shahraray, Maryam S., Hadavi, Khosrow
• Primary Examiner(s): MacDonald, Allen
• Application Number:
  US07/284,165
• Time in Patent Office: 636 Days
• Field of Search: 364/403, 364/401, 364/468, 364/478
• US Class Current: 700/102
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32256 Due dates, pieces must be ready, priority of dates, deadline
• CPC Class Codes: G05B 2219/32265 Waiting, queue time, buffer
• CPC Class Codes: G05B 2219/32304 Minimize flow time, tact, shortest processing, machining time
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method is disclosed for controlling the release of jobs from a pool of pending jobs into a factory, which includes a plurality of machines processing jobs-in-progress, which comprises the following steps. First, a continuity index (CI) is calculated for one of the jobs in the job pool, which is related to the total amount of processing time required by that job, and the antipicated time to finish that job. Second, a mean continuity index (MCI) is calculated related to the CI of all of the jobs processed by the factory in a predetermined period of time. Third, a lower range (r₁) and an upper range (r₂) are calculated which are releated to the utilization factor of the machines and the fraction of jobs which are on time. Finally, a job is released from job pool into said factory if:

MCI-r.sub.1 ≦CI≦MCI+r.sub.2

otherwise, the steps are repeated for the other jobs remaining in the job pool.

Claims

1. A method for controlling the release of jobs from a pool of pending jobs into a factory including a plurality of machines processing jobs-in-progress, said method comprising the steps of:

providing a job release scheduler for controlling release of a job from the pool of pending jobs into the factory, said job release scheduler having inputs connected to the machines and other components of the factory relating to an amount of time required to process a job in the factory and an amount of time anticipated to complete the job within the factory including waiting time at the machines;

calculating a continuity index (CI) for one of the jobs in said pool of pending jobs, said continuity index being related to the total amount of processing time required by said one of said pending jobs, and the anticipated time to complete said one of said pending jobs;

calculating a mean continuity index (MCI) related to an operational parameter of said factory according to management objectives for processing and completing a job in said factory;

calculating a lower range (r1) and an upper range (r2) related to said management objectives; and

operating said job release scheduler for releasing said one of said jobs into said factory if;

space="preserve" listing-type="equation">MCI-r1<

CI<

MCI+r2.

2. The method of claim 1, wherein said continuity index calculating step comprises the step of calculating the mathematical formula:

##EQU4##

3. The method of claim 1, wherein said mean continuity index calculating step comprises the steps of:

calculating the time distribution of the continuity indices of all jobs processed by said factory in a predetermined period of time; and

using the mean of said time distribution as said mean continuity index.

4. The method of claim 3, wherein said mean continuity index MCI is calculated by the mathematical formula:

##EQU5## where N is the number of jobs-in-progress processed by said factory in said predetermined period of time.

5. The method of claim 1, wherein said range calculating step comprises the steps of:

calculating the relationship of said management objectives to different range (r) values;

selecting as said range (r) the value (r*) which results in maximizing the management objectives.

6. The method of claim 1, wherein:

said mean continuity index calculating and said range calculating steps are performed once; and

said continuity index calculating and job releasing steps are performed repeatedly whenever it is desired to make a decision to release a job into said factory.

7. The method of claim 1, wherein said mean continuity index calculating step is performed whenever said operational parameter of said factory changes substantially.

8. The method of claim 1, wherein said range calculating step is performed whenever said management objectives change substantially.

9. Apparatus for controlling the release of jobs from a pool of pending jobs into a factory including a plurality of machines processing jobs-in-progress, comprising:

a job release scheduler for controlling release of a job from the pool of pending jobs into the factory, said job release scheduler having inputs connected to the machines and other components of the factory relating to an amount of time required to process a job in the factory and an amount of time anticipated to complete the job within the factory including waiting time at the machines;

means for calculating a continuity index (CI) for one of the jobs in said pool of pending jobs, said continuity index being related to the total amount of processing time required by said one of said pending jobs, and the anticipated time to complete said one of said pending jobs;

means for calculating a mean continuity index (MCI) related to an operational parameter of said factory according to management objectives for processing and completing a job in said factory;

means for calculating a lower range (r1) and an upper range (r2) related to said management objectives; and

means for operating said job release scheduler for releasing said one of said jobs into said factory if;

space="preserve" listing-type="equation">MCI-r1<

CI<

MCI+r2.

10. The apparatus of claim 9, wherein said continuity index calculating means comprises means for calculating the mathematical formula:

##EQU6##

11. The apparatus of claim 9, wherein said mean continuity index calculating means comprises:

means for calculating the time distribution of the continuity indices of all jobs processed by said factory in a predetermined period of time; and

means for using the mean of said time distribution as said mean continuity index.

12. The apparatus of claim 9, wherein said mean continuity index calculating means comprises means for calculating the mathematical formula:

##EQU7## where N is the number of jobs-in-progress processed by said factory in said predetermined period of time.

13. The apparatus of claim 9, wherein said range calculating means comprises:

means for calculating the relationship of said management objectives to different range (r) values;

means for selecting as said range (r) the value which results in maximizing the management objectives.

14. A factory for processing jobs-in-progress, and producing completed work, said factory comprising:

a plurality of machines, at least one of which includes a waiting queue of jobs to be processed thereat, said at least one machine providing status information relating to its respective waiting queue;

a source of jobs in a pool to be processed in the factory, and job storing means for storing the pool of pending jobs to be processed;

a job release scheduler for controlling release of jobs from the pool of pending jobs into the factory, said job release scheduler receiving said waiting queue status information from said at least one machine in order to determine amounts of time required to process jobs in the factory and amounts of time anticipated to complete jobs within the factory including waiting time at the machines;

means for calculating continuity indexes (CI) for the jobs in said pool of pending jobs, said continuity indexes being related to the amount of processing time required by the pending jobs, and the anticipated time to complete the pending jobs;

means for producing selection information for selecting an order of jobs to be released into the factory;

means for providing job release criteria according to management objectives for processing and completing jobs in said factory, including a mean continuity index (MCI) related to an operational job release parameter of said factory and a lower range (r1) and an upper range (r2) for said mean continuity index; and

means, responsive to said machine waiting queue status information, said job storing means, said means for calculating continuity indexes, said means for producing selection information, and said means for providing job release criteria, for operating said job release scheduler for releasing said pending jobs into said factory when said continuity indexes (CI) satisfy the following relation;

space="preserve" listing-type="equation">MCI-r1<

CI<

MCI+r2.

15. The factory of claim 14, wherein said selection information producing means comprises a computer.

16. The factory of claim 14, wherein said order storing means comprises a data base stored on a computer.

17. The factory of claim 14, wherein said selection information producing means and said order storing means are comprised on the same computer.

18. The factory of claim 14, wherein said machines are controlled by a computer system directly connected to said information producing means and order storing means computer.