Author/Authors :
P.-H. Lin، نويسنده , , D.S.-H. Wong، نويسنده , ,
S.-S. Jang، نويسنده , , S.-S. Shieh and
J.-Z. Chu، نويسنده ,
Title Of Article :
Controller design and reduction of
bullwhip for a model supply chain
system using z-transform analysis
Latin Abstract :
In this work, a discrete time series model of a supply chain system is derived using material balances and information flow.
Transfer functions for each unit in the supply chain are obtained by z-transform. The entire chain can be modeled by combining
these transfer functions into a close loop transfer function for the network. The model proves to be very useful in revealing the
dynamics characteristic of the system. The system can be viewed as a linear discrete system with lead time and operating constraints.
The stability of the system can be analyzed using the characteristic equation. Controllers are designed using frequency analysis. The
bullwhip effect, i.e. magnification of amplitudes of demand perturbations from the tail to upstream levels of the supply chain, is a
very important phenomenon for supply chain systems. We proved that intuitive operation of a supply chain system with demand
forecasting will cause bullwhip. Moreover, lead time alone would not cause bullwhip. It does so only when accompanied by demand
forecasting. Furthermore, we show that by implementing a proportional intergral or a cascade inventory position control and
properly synthesizing the controller parameters, we can effectively suppress the bullwhip effect. Moreover, the cascade control
structure is superior in meeting customer demand due to its better tracking of long term trends of customer demand.
NaturalLanguageKeyword :
cascade control , Supply chain , z-transform , Bullwhip effect , PI control , Frequency analysis
JournalTitle :
Studia Iranica
