Means and ends of control

Means-end analysis plays a significant role in cognitive engineering and has been successfully applied in several work domains, usually in the form of Rasmussens abstraction hierarchy. However, work domains with embedded controls create problems and modifications of the abstraction hierarchy has been proposed to circumvent the problems. But embedded controls is a deep problem for means-end analysis in general and not only for instances like the abstraction hierarchy. It is pointed out that means-end analysis is currently not used in control engineering but should be used to clarify modelling assumptions. Means-end analysis also lacks a proper definition of the control concept. It is proposed that control is defined as a binary relation that assign functional roles to subsystems. This control concept leads to distinct but entangled process and control hierarchies. It is argued that the problems of embedded control can be resolved by an analysis of the relations between the two types of hierarchy. Illustrative modelling examples are included