Expert system scheduler

• US 5,040,123 A
• Filed: 09/08/1989
• Issued: 08/13/1991
• Est. Priority Date: 09/08/1989
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Burridge, Kenneth L., Osterfeld, David H., Barber, Karon A.
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US07/405,692
• Time in Patent Office: 704 Days
• Field of Search: 364/468, 364/513, 364/401, 364/402, 364/403, 364/149-151
• US Class Current: 700/100
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32252 Scheduling production, machining, job shop
• CPC Class Codes: G05B 2219/33002 Artificial intelligence AI, expert, knowledge, rule based system KBS
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y02P 90/80 Management or planning
• CPC Class Codes: Y10S 706/904 Manufacturing or machine, e.g. agricultural machinery, machine tool

Abstract

An expert system scheduler is disclosed which uses heuristics developed by an experienced factory scheduler. The scheduler uses these heuristics to generate schedules. Forward and backward scheduling is used at different stages of the schedule generation process.

Claims

1. A computer implemented method of scheduling a plurality of machine operations in a predetermined sequence in a factory containing a plurality of machines and a factory control system which controls the machines in accordance with the schedule, comprising the steps of:

a. constructing a computer model of the factory comprising data relating to the production of parts including inventory, operations, machines, and at least one customer order,

b. scheduling the machine operations necessary to produce the parts in the customer order in the reverse order of routing with the last operation being scheduled first and the first operation being scheduled last,

c. modifying the schedule defined in scheduling step b. by removing machine operations which are unnecessary due to existing factory part inventory to thereby better utilize available machine capacity,

d. further modifying the schedule produced in schedule modifying step c. by shifting certain operations forward in time to insure that no operations are scheduled prior to a predetermined build context time.

2. The invention defined in claim 1 comprising the further step of modifying the schedule produced in schedule modifying step d of claim 1 to include preventive maintenance jobs on machines requiring same during the scheduling horizon.

3. The invention defined in claim 2 comprising the further step of modifying the schedule to front load the schedule.

4. The invention defined in claim 1 comprising the further step of modifying the schedule, if lateness is anticipated for customer orders, by removing machine operations which are unnecessary due to existing safety stock to thereby minimize lateness.

5. The invention defined in claim 1 comprising the further step of modifying the schedule, by forward scheduling the necessary operations to replenish safety stock to a predetermined level.

6. The invention defined in claim 1 wherein step b comprises the steps of,sorting customer orders by due date,considering each of the sorted orders in sequence,considering each operation required to produce the part in the order in the reverse sequence of routing,selecting a machine capable of performing a given operation,defining a desirable window of time during which the operation can be performed.