A State-Behavior-Function Based Approach for Functional Modeling of Multi-State Systems and its Application

As a critical task of conceptual design, function modeling is regarded as a design activity aimed at establishing the functional model(s) of a technical system. Existing functional modeling approaches usually employ a static diagram to represent the functional structure of a technical system, which, on one hand, cannot allow a system engineer to explicitly represent a system that has multiple states, and on the other hand, cannot effectively support system state analysis. Therefore, this paper proposes a state-behavior-function-based approach for achieving the function modeling of multi-state systems to address the above issues. It first introduces the state-behavior-function-based models for representing an object (i.e., a component or a system). Hereby, a state of an object refers to the internal configuration of the object, a behavior represents the state (i.e., configuration) change of the objet, and a function denotes the intended action that the object exerts on one or multiple flows in the environment of the object. This research then proposes an object-based approach for simulating the functional processes in a multi-state system. With this approach, each component of a system is treated as an active object (rather than a static block node in the functional diagram), which can be in different states and can interact with other components or subsystems through the input and output flows. A prototype system is then developed, which cannot only be used for function modeling, but also can be employed for system state simulation. The function modeling of a washing machine and its system state simulation has been employed to illustrate the proposed approach.