Abstract
In the automotive industry, the electrical wirings are needed in a very large
number of different configurations, depending on the options requested by the customer.
Renault uses a Make To Stock strategy so that electrical wiring harnesses must be
standardized. A given configuration can be replaced by a more complete, therefore more
expensive one. The diversity management problem consists in choosing an optimal set of
some given number of configurations that will be produced, any nonproduced configuration
being replaced by the cheapest produced one that is compatible with it.
For the last 10 years, this diversity management has been one of the focus for most
automotive manufacturers and suppliers. However, the economic performance of available
solutions is very limited. They are, most of the time, based on a very poor description of
actual car orders (coming from rough assumptions on equipment mounting rates). Moreover,
the computational time is often very important due to the very high number of possible
assembly combinations (10^12 to 10^15) when no further information is available.
Renault developed an original optimization approach for this problem with two important
features :
- The optimization process is based on a sophisticated mix of recent and forecasted car orders.
Recent orders database guarantees a good economic performance of the produced wiring
harnesses diversity at short term. Forecasted car orders database ensures that this economic
performance does not decrease over a mid-term period with the evolution of customer
demand.
- All the information available about possible and impossible assemblies is used to reduce the
number of combinations, so that a nearly-optimal solution is given within a very short
computational time. This allows a very interactive and efficient aid decision process.
As a result, this work allowed a cost reduction of several euros per vehicle.
Keywords - Optimization, Diversity Management, Wire Harnesses, Cost Reduction, Robustness