Abstract
Besides coping with the highly dynamic product and production system life cycles with ever-changing requirements, modern assembly systems also need to be userfriendly. Their modularity at fine granularity-level combined with local intelligence and a distributed control approach allows the systems to evolve together with the requirements but their complexity would soon not be manageable from outside any more if user-friendliness was not considered a major criterion. Systems must be made to serve their users. Thanks to Self-* capabilities, systems can gain an increasingly high degree of autonomy. Diagnosis plays a particularly important role in this process.