Inexact genetic algorithm approach to target values setting of engineering requirements in QFD

In Quality Function Deployment, determination of the target values for engineering requirements is the most difficult process. A fuzzy optimization model is presented for the determination of target values for engineering requirements in Quality Function Deployment. An inexact genetic algorithm approach was introduced to solve the model that takes the mutation along the weighted gradient direction as a genetic operator. Instead of obtaining one set of exact optimal target values, the approach can generate a family of inexact optimal target values setting within an acceptable satisfaction degree. Through an interactive approach, a design team can determine a combination of preferred solution sets from which a set of preferred target values of engineering requirements based on a specific design scenario can be obtained. An example of car door design is used to illustrate the approach.