Title: Computeraided selection of equipment and resource planning in assembly line design
1- Computer-aided selection of equipment and
resource planning in assembly line design - Collaboration FABRICOM - University of
Brussels 01/09/95 - 31/08/99 - Fabrice Pellichero
2Contents of the presentation
- Framework of the project
- The equipment pre-selection method
- The automatic resource planning tool
- Conclusions and further works
3Framework of the project
4Equipment pre-selection (1)Basic principles
- Based on the use of Functional Groups (FGs)
- Definition Set of equipment able to execute a
given assembly operation. - Goal of the pre-selection tool
- propose a set of feasible FGs for each
operation - Each FG has an associated
- cost,
- operating time,
- availability.
5Equipment pre-selection (2)Building of a FG
6Equipment pre-selection (3)Hidden times
7Automatic resource planning (1)Input data
- Cycle time
- Precedence constraints
- For each operation a set of Functional Groups
with an associated - cost,
- duration,
- availability.
8Automatic resource planning (2)Output data
- Contents of the detailed logical layout
- number of workstations,
- operations executed by each workstation,
- relative position of the workstations.
- Assembly line optimized for three major criteria
- operating times,
- cost of the line,
- availability of the line.
9Automatic resource planning (3)Genetic
Algorithms (GAs)
- Inspired from evolution of species in Nature
(objective function acts as environment) - Maintain a population of solutions
- Work with a representation of the solutions
(chromosomes) - New solutions created by combining the best
members of the population (heredity) - New solutions replace the worst members of
the population (survival of the fittest)
10Automatic resource planning (4)Grouping Genetic
Algorithms (GGAs)
- Special kind of GAs designed to solve grouping
problems
Wiley, 1998. ISBN 0-471-97150-2
11Automatic resource planning (5)Branch and Cut
algorithm
- Enumerates all the possible solutions with the
help of a search tree - Cuts the branches of the search tree when it can
be proven that - the node does not contain an optimal solution
- the node does not contain a valid solution
12Automatic resource planning (6)The PROMETHEE II
method
- Multicriteria decision-aid method based on the
use of - preference functions associated to each criterion
- weights associated to each criterion
- Computes a net flow ?, which gives a complete
ranking between the alternatives - Needs very small computation times while avoiding
the disadvantage of a complete aggregation
13Automatic resource planning (7) Individual
Construction Algorithm (ICA)
- 1. Assign tasks (or operations) to the
workstations (using the operating time
corresponding to the fastest equipment) according
to an Equal Piles strategy - 2. Generate all possible equipment combinations
for each station thanks to a Branch Cut
algorithm - 3. Select the best equipment combination for each
station using the multicriteria decision-aid
method PROMETHEE
14Automatic resource planning (8) The GGA steps
- 1. Create a population of individuals using the
Individual Construction Algorithm - 2. Use the decision-aid method PROMETHEE to
order individuals in the population - 3. Recombine (mate) best individuals (parents) to
produce children (with use of the ICA) - 4. Mutate children (with use of the ICA)
- 5. Use PROMETHEE to order the new population
- 6. Replace the worst individuals of the
population by the new children. - 7. If a satisfactory solution has been found
stop. Else go to 3
15Automatic resource planning (9)Main features of
the algorithm
- The PROMETHEE II net flow is used instead of a
classical cost function for the ordering of the
solutions in the GGA - Elitism is used the best-ever solution takes
part in the evaluation of the net flows - Allows a real multicriteria optimization because
all the criteria are considered simultaneously at
each generation
16Conclusions and further works (1)Advantages of
the resource planning method
- The method allows a real global optimization of
the line thanks to - the use of precedence constraints instead of a
fixed assembly sequence - the equipment pre-selection tool which proposes
several FGs by operation - The method allows a real multicriteria
optimization thanks to the use of PROMETHEE
17Conclusions and further works (2)Next
development steps
- Testing on industrial case studies
- Enrichment of the equipment database
- Possibility of automatic link with a simulation
tool - Treatment of the multivariant products