Hierarchical Control of Hybrid Systems

The topic of this contribution is the synthesis of hierarchi cal control systems for hybrid problems. We outline a method that is based on a hierarchy of models describing the plant at various levels of abstraction and a decomposition of the overall specification. The proposed method captures severa l k y requirements for hierarchical control: it includes the notion of information aggregation between adjacent con rol levels; it allows for a combination of continuous and discrete event controllers on various levels of the hierarc hy; omplexity of the synthesis procedure and the resulting control scheme is considerably reduced when compared to an u nstructured (and therefore non-hierarchic) approach; finally, it provides a mathematical guarantee that the speci fied hierarchical interaction between the different contro lle levels does indeed solve the overall problem. The method is i llu trated by an example from process control, the synthesis of a discrete start-up scheme for a distillation c olumn.