Originally posted by: noneless

Hi all.

I'm trying to develop a production scheduling model with following description:

The model is a production of a three-parts device witch can perform on 6 machines. Each part also performs on several operation witch can be done on any of the 6 machines. The objective of model is minimizing sum of the cost occurring when one operation of a specific part, performs on a machine an the immediate operation witch comes next, performs on another machine. I have a matrix contains the switching costs between machines and I want to calculate this machine switching cost based on the matrix. For example one operation of a specific part, performs on machine 1 and the immediate operation witch comes next, performs on machine 3. I want to return cost(1,3) from the costs matrix.

I define intervals for operations of parts and sequences for machines.But i can't access immediate interval of a specific part witch comes next in another sequence (like the attached picture). So I can't find the switching cost.

I appreciate if anyone could help me.

Originally posted by: PhilippeLaborie

Hello,

Do you know in advance the order of operations on the parts? For instance do you have a precedence constraint in the model before Operation 2 of part 1 and Operation 3 of part 1 ?

If yes, the cost only depends on the machine selection: if the execution of operation i on machine j is represented by an optional interval variable op_i_j, you will use boolean expressions p_i_j=presenceOf(op_i_j) to express the cost. On your example, the easiest way is to do: costOp2Op3 = sum(j2 in MachinesOp2, j3 in MachinesOp3) cost(j2,j3) * p_j2 * p_j3.

Philippe

Originally posted by: noneless

Thx PhilippeLaborie

I defined another sequence variable on parts and problem just solved