@conference{Chen2003, author = {F.Y. Chen and S.M. Disney}, title = {The order-up-to policy sweet spot: Using proportional controllers to eliminate the bullwhip problem}, booktitle = {EurOMA POMS Conference}, year = {2003}, pages = {551-560}, address = {Como Lake, Italy}, month = {16th-18th June}, url = {https://www.researchgate.net/publication/248799216_The_order_-_up_-_to_policy_sweet_spot_-_Using_proportional_controllers_to_eliminate_the_bullwhip_problem}, abstract = {We develop a discrete control theory model of a stochastic demand pattern with both Auto Regressive and Moving Average (ARMA) components. We show that the bullwhip effect arises when the myopic Order-Up-To (OUT) policy is used. This policy is optimal when the ordering cost is linear. We then derive a set of z-transform transfer functions of a modified policy that allows us to avoid the bullwhip problem by incorporating a proportional controller into the inventory position feedback loop. With this technique, the order variation can be reduced to the same level as the demand variation. However, bullwhip-effect avoidance in our policy always comes at the costs of holding extra inventory. When the ordering cost is piece-wise linear and increasing, we compare the total cost per period under the two types of ordering policies: with and without bullwhip effect reduction. Numerical examples reveal that the cost saving can be substantial if order variance is reduced using the proportional controller.} }