Genetic algorithms in optimal safety system design

This paper describes a design optimization scheme for systems that require a high likelihood of functioning on demand. For safety systems whose failure could result in loss of life it is imperative that the best use of the available resources is made and that a system which is optimal and not just adequate is produced. To demonstrate the practicalities of the method it has been applied to a high-integrity protection system. Analyses of individual system designs are carried out using the latest advances in the fault tree analysis technique utilizing the binary decision diagram approach. A genetic algorithm (GA) is used to perform the optimization resulting in the final design specification. Techniques are introduced to penalize the fitness of infeasible designs and to incorporate these values into the GA. The latter part of the paper considers the effect of varying parameters, which affect the action of the GA. A parameter combination is suggested which may achieve the most effective exploration of the search space and, thus, result in the best system design. Having implemented the GA it became apparent that areas of the algorithm could be improved. The latter part of the paper investigates suggested improvements to particular processes of the scheme.