Application of Fuzzy Control to System Dynamics Modelling

The origin of uncertainties in System Dynamics (SD) modelling is to be found in the vagueness and imprecision in the knowledge of the system under focus. This chapter analyses an advanced SD approach based on techniques pertaining to fuzzy control. The aim is to have enhanced pro-active capabilities for planning and control of decision processes. When preparing a SD model one has to take care of uncertainties affecting technical parameters, initial conditions and the quantification of the influence links between the variables. These links are usually represented by analytical functions, or by means of lookup tables. In the present chapter fuzzy techniques are proposed to deal with these uncertainties. Technical parameters and initials conditions are represented by fuzzy sets corresponding to vagueness statements. Influence links between variables are represented either by algebraic operations combining ordinary and fuzzy numbers, or by sets of logical rules replacing lookup tables. It is shown how the fuzzy-control formulation can be easily implemented by using the sensitivity tools available in SD simulation codes, like VENSIM® DSS. The use of this fuzzy approach is demonstrated by means of a fishery management problem.

ISBN:978-1-61324-488-3

Publication year:2011

Keywords:System Dynamics, Control Theory, Fuzzy Logic