Making control systems visible

Abstract

In this paper we discuss how to support interface design of automatic control systems in a systematic way, that is, how to identify the information that should be displayed in a cognitive relevant way and how to visualize this information content in the interface efficiently. First, a means-ends hierarchical structure is adopted to build the functional model of a control system. Then, a set of functional primitives is proposed, and their behavioural explanations are given. These primitives are used to describe the functions in a functional model of a control system. Based on the functional model, the necessary information to be visualized in the interface can then be identified. Third, a library of graphical presentations for the set of functional primitives is set up. To overcome the problem of display complexity and improve operators’ cognitive workload, the concept of “functional macro” is adopted. Furthermore, several principles are proposed to explain how to map a functional model to interface displays. Finally, how to use this approach to support interface design of automatic control systems is explained in detail by using the electrical and hydraulic controller (EHC) of a nuclear power plant (NPP) as an example. A simple experiment showed that the display design of EHC in this study could be more helpful to identify the modes of EHC than a SSSI design. Reusability of the set of functional primitives and their graphical presentations make this approach possible to support designing displays of various control systems.