A Switched System Approach For The Bullwhip Effect Control Of Supply Chain Systems

As an important pattern of economic value chains, efficiency management of supply chain network systems serves as a crucial role in the development of modern companies. Effective supply chain management can make companies response properly to market changes, optimize the allocation of resources, reduce production costs, improve economic efficiency, and bring lasting competitive advantage for companies as well. However, in supply chain management systems, due to the error of information transmission, the product demand is distortedly amplified along with members on the supply chain, even exhibits some instability phenomenon. This fact is called the bullwhip effect that often disrupts the production plan, and increases the difficulty of the management of companies. Therefore, the key issue in studying the bullwhip effect problem is to deign strategies restraining it effectively. Meanwhile, these strategies make sure that supply chain systems function economically; especially optimized scenario is provided for supply chain inventory. This work has significant interest in both theoretical and practical aspects.This dissertation is devoted to the problem of bullwhip effect for supply chain systems. Through the analysis of causes of the bullwhip effect and stability of supply chain network systems, the problem of stabilization control with inhibition of the bullwhip effect is addressed by using the switched system approach with respect to the delays of information transmission and switches of topology of supply and demand. The main results of the present dissertation are summarized as follows.(1)Considering the fact that decision information of order perturbation compensation can not be accessible duly, two models are obtained according to the accessibility of decision information of order perturbation compensation. The problem of restraining the bullwhip effect is thus transformed into a stabilization problem of a switched system. A sufficient condition is provided to ensure that the supply chain inventory system is exponentially stable and the order compensation control strategy is given.(2)Considering time-varying delays in supply chain network systems, a state-space model is established for the supply chain inventory. Due to the time-varying delay, the problem of restraining the bullwhip effect is transformed into stabilizing a set of switched systems with finite number of subsystems. A sufficient condition is presented to ensure that the closed-loop supply chain inventory system is exponentially stable. Furthermore, the order compensation controller of the inventory fluctuation is derived.(3)Aiming to the constraints such as inventory and productivity in the operation of supply chain network systems, the problem of restraining the bullwhip effect is transformed into a stabilization problem against both time-varying delays and constraints. Based on the switched system model, a control strategy with optimized performance and order variation constraint is obtained by using the switched model predictive control method.(4)The phenomenon that companies change frequently their suppliers and uncertain customer demands in supply chain network systems, the problem of restraining the bullwhip effect is transformed into stabilizing a set of switched systems with switching topology and disturbance. Based on the robust control and Lyapunov stability theory, the order compensation strategy is provided.(5)The bullwhip effect can also be caused by some uncertain factors, such as changes in customer demand or production plan. A switched system model with norm-bounded uncertainties is established for supply chain systems with time-varying delays and these uncertain factors. Moreover, a designed method is proposed for the guaranteed cost controller with quadratic stability.Simulations are also included to show the effectiveness of the proposed methods. Finally, the conclusion and perspectives are given.