Forcing function and time delay in qualitative simulation
Mario Tétreault, Bernard Marcos, Jean‐François Lapointe · WIT transactions on information and communication technologies · 1970
Many potential uses of qualitative simulation (QS), such as control systems, require adding functions with explicit time to describe actions taken by agents. Also, many control systems have time delay. Therefore, the modelling of the physical world must consider the effects of actions and time delay. This paper shows how to extend qualitative simulation to include actions and functions with time delay. The effects of actions are some forced variables (or parameters) added to the description of the system. Our algorithm treats these new parameters like state variables (i.e. system parameters) but their possible state transitions are reduced. In our algorithm, a function with a pure time delay is an additional variable corresponding to the same variable without delay. This function is similar to a forcing function but our algorithm builds its definition during the simulation. The representation of the forcing functions and the functions with time delay are purely qualitative or semiquantitative. The integration of these functions to QSIM permits its application to control systems. The example shows that qualitative time delay, forcing function and feedback system can be simulated. Transactions on Information and Communications Technologies vol 1, © 1993 WIT Press, www.witpress.com, ISSN 1743-3517 110 Artificial Intelligence in Engineering