In a multi-color printing press consisting of multi-printing units, the dynamics of each unit are coupled and the signal propagation between two neighboring printing units is always with delay. A challenging issue for control of the printing press is how to handle the web pass such that the multi colors are printed with high precision. This paper presents a delay-dependent nonlinear control approach to printing positioning control in a three-color printing press. First, a nonlinear coordinate transformation is introduced to a state space model that describes the dynamics of the tension and the printing error. Then, based on the new dynamical model, two feedback control schemes are proposed. A state feedback controller is designed such that tension errors and printing errors converge to zero, and an output feedback controller is proposed to perform the state feedback control law without tension sensors. Furthermore, simulation and experiments are performed to demonstrate the effectiveness of the proposed control scheme.
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