Research On Modelling And Control Strategies For Dynamic Supply Chain Systems

This paper studies the modelings of different dynamic supply chain systems by analyzing the various factors in market environment,firstly,then the control strategies to reduce the bullwhip effect of dynamic supply chain systems are concerned.The details are listed as follows:1.The sliding mode control for the dynamic supply chain system subject to demand disturbance of market is concerned.For the problem of bullwhip effect causing by demand disturbances of market and the parameter perturbations,a nonlinear uncertain model of the supply chain system is constructed first.Then,a sliding mode control scheme and an optimal sliding mode control scheme are proposed to stabilize the supply chain systems.It is found through simulation results that both the designed sliding mode controller and the optimal sliding mode controller can improve the performance of the supply chain systems.Moreover,the control scheme is better than the sliding mode control scheme.2.A robust output feedback control to reduce the bullwhip effect of dynamic supply chain systems based on an interval-like demand prediction scheme is considered.By introducing an interval-like time-varying delayed state signal to predict the order variations of downstream sites and taking into account the parametric perturbations,the dynamic supply chain is modeled as an uncertain linear discrete-time system with interval-like time-delay.Then,robust output feedback control schemes are proposed to improve the performance of the supply chain system.Some sufficient conditions to the existence of the robust output feedback controller are derived.It is found from simulation results that the designed output feedback controllers can effectively stabilize the supply chain system with intervallike time-delay and parametric perturbations.Moreover,if the introduced interval-like time-delays are selected properly,the bullwhip effect of the supply chain systems is reduced significantly.3.A dynamic modeling and robust state feedback stabilization of a supply chain via demand combination prediction schemes are concerned.First,by using the several past demand signals of the downstream sites of the supply chain,a new combined prediction scheme of demand of the downstream sites is proposed.Then the supply chain under consideration is modeled as an uncertain linear system with multiple state time-delays.Third,some delay-dependent sufficient conditions of the robust state feedback stabilization of the supply chain and the design method of the controller are presented.Some simulations are given to demonstrate the effectiveness of the designed robust state feedback controller and the linear combination demand prediction schemes.It is found from simulation results that under the new demand prediction schemes and the designed controllers,the bullwhip effect is reduced effectively and the performance of the supply chain is improved remarkably.