Allocation method for generating a production schedule

• US 5,548,518 A
• Filed: 05/31/1994
• Issued: 08/20/1996
• Est. Priority Date: 05/31/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wittrock, Robert J., Dietrich, Brenda L.
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): Garland, Steven R.
• Application Number:
  US08/251,812
• Time in Patent Office: 812 Days
• Field of Search: 364/401-403, 364/468, 364/478
• US Class Current: 700/100
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling

Abstract

A novel allocation method for generating a feasible production schedule. The method, in response to a specified requirement q, comprises the steps of determining what quantity (r) of a product can be produced with a specified quantity of supply components; allocating a required quantity of supply components for filling a thus defined partial order; and filling a remainder of the requirement (q-r) at some later time.

Claims

1. An allocation method for utilization within a computer for generating a feasible production schedule in response to a specified requirement q, the method comprising the computer implemented steps of:

(1) determining what quantity (r) of a product can be produced with a specified quantity of supply components;

(2) allocating a required quantity of supply components for filling a thus defined partial order; and

(3) filling a remainder of the requirement (q-r) at some later time;

wherein the steps (1) and (2) and (3) are quantitatively determined by simultaneously solving within the computer a material balance constraint (MBC) inequality and a capacity availability constraint (CAC) inequality, wherein

(i) the MBC comprises a step of comparing

a) a quantity of product for external requirement (over an arbitrary time period) plus a total usage of parts in a production of other parts (over the same arbitrary time period), with

b) a total external availability of parts (over the arbitrary period) plus a total production of parts lover the arbitrary period); and

(ii) the CAC comprises a step of comparing

a) a total quantity of resource (used in the arbitrary time period) with

b) an availability of resource (in the arbitrary time period);

so that if there is not sufficient capacity or material available to meet every requirement, the solution allocates available resources in favor of requirements with high priority.

2. A method according to claim 1, comprising the step of quantitatively defining the MBC inequality and the CAC inequality so that the following inequalities obtain:

##EQU11## where, w_i,t is a decision variable denoting the total quantity of part number P/N i made available to meet requirement in period t;

a_i,j,t,τ

is a data element denoting a quantity of P/N i required in a period t to produce one unit of P/N j in period τ

;

x_j,τ

is a decision variable denoting quantity of P/N j produced in period t ε

{1,2, . . . T};

e_i,t is a data element denoting an external supply of j in period t;

x_i,t is a decision variable denoting a quantity of P/N j produced in period t ε

{1,2, . . . T};

g_r,j,t,τ

is a data element denoting the quantity of resource r required in period t to produce one unit of P/N j in period τ

;

c_r,t is a data element denoting the quantity of resource r available in period t.

3. A method according to claim 2, comprising a step of simultaneously solving the MBC and CAC inequalities by:

(1) setting w_j,t =0 and x_j,t =0 for all j ε

J and t ε

{1,2, . . . , T};

JT={(j ε

J, t ε

{1,2, . . . , T})|v_j,t >

0}; and

doing while JT≠

.0.;

(2) selecting a pair (j, t) ε

JT having a highest priority and setting v=v_j,t ;

(3) determining v^* as a minimum of;

a requirement quantity v, and a maximum quantity of P/N j that can be made available for external requirements in period t subject to the availability of material and capacity;

(4) determining a production schedule y_j,t for all j ε

J and t ε

{1,2, . . . , T} necessary to support the external availability of v^* units of P/N j in period t;

(5) updating a solution w_j,t ←

w_j,t +v^*, x_j,t ←

x_j,t +y_j,t all j ε

J and t ε

{1,2, . . . , T};

(6) updating material availability e_j,t according to standard materials requirement planning netting logic; and

capacity availability c_r,t according to standard capacity requirements planning logic; and

(7) updating a set JT;

JT←

JT-(j, t).

4. A method according to claim 3, wherein step (3) comprises determining a maximum amount of product by solving a linear program.

5. A method according to claim 3, wherein step (3) comprises determining a maximum amount of product by computing a ratio test.

6. A method according to claim 3, comprising determining a maximum of product by implementing step (3) as a line search.

7. A method according to claim 1, comprising the step of quantitatively determining the recited limitations by simultaneously solving a material balance constraint (MBC) inequality and a capacity availability constraint (CAC) inequality, wherein

(i) the MBC comprises a step of comparing

a) a total part shipment (over an arbitrary time period) plus a total usage of parts in a production of other parts (over the same arbitrary time period), and

(b) a total external availability of parts (over the arbitrary period) plus a total production of parts (over the arbitrary period);

and

(ii) the CAC comprises a step of comparing

a) a total quantity of resource (used in the arbitrary time period) with

b) an availability of resource (in the arbitrary time period);

so that if there is not sufficient capacity of material available to meet every demand, the solution allocates available resources in favor of demands with high priority.

8. A method according to claim 7, comprising the step of quantitatively defining the MBC inequality and the CAC inequality so that the following inequalities obtain:

##EQU12## where, s_d,t is a decision variable denoting a shipment for demand d ε

D in period t ε

{1,2, . . . T};

a_i,j,t,τ

is a quantity of part number P/N i required in a period t to produce one unit of P/N j in period τ

;

x_j,τ

is a decision variable denoting a quantity of P/N j produced in period τ

ε

{1,2, . . . T};

e_i,t is an external supply of j in period t;

x_i,t is a decision variable denoting a quantity of P/N i produced in period t ε

{1,2, . . . T};

g_r,j,t,τ

is a quantity of resource r required in period t to produce one unit of P/N j in period τ

;

c_r,t is a quantity of resource r available in period t.

9. A method according to claim 8, comprising the steps of simultaneously solving the MBC and CAC inequalities by the steps of:

(1) setting S_d,t for all d ε

D and t ε

{1,2, . . . T} and setting x_j,t =0 for all j ε

J and t ε

{1,2, . . . T};

(2) selecting a demand d ε

D having a highest priority;

(3) determining v^* as a minimum of;

the demand quantity v, and the maximum quantity of P/N p that can be completed in period t subject to the availability of material and capacity;

(4) determining a production schedule y_j,t for all j ε

J and t ε

{1,2, . . . T} necessary to support the shipment of v units of P/N p in period t;

(5) updating a solution

space="preserve" listing-type="equation">S.sub.d,t ←

S.sub.d,t +v.sup.*

space="preserve" listing-type="equation">X.sub.j,t ←

X.sub.j,t +y.sub.j,t all j ε

J and t ε

{1,2, . . . T};

(6) updating material availability e_j,t according to standard materials requirement planning netting logic;

updating capacity availability c_r,t according to standard capacity requirements planning logic; and

(7) updating a demand set D←

D-d.

10. A method according to claim 1, comprising modifying and revising demand specification set D for addressing backlogging and comprising the steps of:

(1) determining the remaining demand quantity through use of a backlogging function; and

(2) updating the priority of the demand.

11. A method according to claim 1, comprising a step of performing a more equitable allocation by dividing initial demands and adjusting relative priorities.

12. A method according to claim 11, comprising a step of defining a split demand set for obtaining an algorithm that both allocates equitably and backlogs demand.