Use of fuzzy logic to overcome constraint problems in genetic algorithms

At Rolls-Royce, studies have been made in three general areas where Genetic Algorithms appear to add something to current methods. These are preliminary design, scheduling and calibration. Each of these areas addresses a number of key issues in the use of Genetic Algorithms in practical problems. The main issues for scheduling problems are large numbers of constraints, the size of the problems and rescheduling requirements in response to actual events. A pilot study undertaken by Rolls-Royce was to schedule the testing of a development engine. Rescheduling to accommodate local changes while maintaining minimum overall change was the major issue and this was resolved by using Game Theory in a hybrid Genetic Algorithm. The third area of calibration addresses the issue of constraints, incorporating 'engineering judgement' and integration with existing code. The pilot study performed in this area is the subject of this paper.