Modelling and robust control of an industrial accumulator in roll to roll systems

This paper concerns the study of an accumulator used in an industrial elastic web processing plant. Accumulators are used to allow unwind or rewind roll changes while the rest of the line remains at a constant web velocity. Linear and nonlinear models of an accumulator are first detailed. These models are derived from the physical relationships that describe web tension and velocity dynamics in each span of the accumulator. The effects of time-varying mechanical parameters on accumulator dynamics and performances are also discussed. These parameters are mainly Young´s modulus, web length and rolls inertia. Finally, the last part of this contribution focuses on the control of web tension in the accumulator. Different regulation schemes are proposed for web tension control. The synthesis of the controllers includes optimized PI controllers or H¿ controllers. Simulation results are discussed for each case.