Analysis and Design of a Production and inventory Control System for Ramp Demand

An Automatic Pipeline, Inventory and Order Based Production Control System (APIOBPCS), which is firstly proposed by Towill in 1982, lies at the heart of many commercial and bespoke ordering systems based on periodic review of stock and production targets. This simple and elegant control system works well, even when dealing with scenarios in which there are many competing value streams. However, when the demand is with time trend (such as ramp demand) rather than step changes, we show via linear s-transform analysis that there will be inventory drift in the APIOBPCS model. An innovative solution named PID-APIOBPCS model is proposed in this paper. In the new model, there are a PI controller in the inventory feedback loop which can eliminate the inventory drift and a PD controller in the order rate policy which can smooth the inventory level. At last, a simulation example is given to illustrate the benefit of PID-APIOBOBPCS model.