Genetic algorithms and flexible process planning in the design of fault tolerant cell control for flexible assembly systems

This paper presents a methodology for the advancement of fault tolerance in cell control when applied to a class of flexible,assembly system. A litera ture survey of flexibility in manufacturing was conducted, which leads to t he formulation of a flexible process planning (FPP) scheme which efficientl y encodes all possible operation plans of products to be manufactured in ty pical automated manufacturing systems. Genetic algorithms are designed whic h can retrieve all working operation plans (WOP) from a FPP database, and c an determine a production schedule and assignment of operations to workplac es which minimise the overall make-span of the job orders in near real-time . The FPP scheme and the genetic algorithm are successfully integrated into a prototype colour Petri net (CPN) based cell control system which allows the system to regenerate its control logic and the production schedules whe never system faults occur, and therefore enable it to continue in operation . The successful implementation of this fault recovery cell control system within a demonstrator assembly cell indicates that the framework proposed p rovides a foundation for the further de development and application of adva nced cell control.